Numerical methods for analyzing electromagnetic scattering

Numerical methods to analyze electromagnetic scattering are presented. The dispersions and attenuations of the normal modes in a circular waveguide coated with lossy material were completely analyzed. The radar cross section (RCS) from a circular waveguide coated with lossy material was calculated. The following is observed: (1) the interior irradiation contributes to the RCS much more than does the rim diffraction; (2) at low frequency, the RCS from the circular waveguide terminated by a perfect electric conductor (PEC) can be reduced more than 13 dB down with a coating thickness less than 1% of the radius using the best lossy material available in a 6 radius-long cylinder; (3) at high frequency, a modal separation between the highly attenuated and the lowly attenuated modes is evident if the coating material is too lossy, however, a large RCS reduction can be achieved for a small incident angle with a thin layer of coating. It is found that the waveguide coated with a lossy magnetic material can be used as a substitute for a corrugated waveguide to produce a circularly polarized radiation yield

Numerical methods for analyzing electromagnetic scattering

Attenuation properties of the normal modes in an overmoded waveguide coated with a lossy material were analyzed. It is found that the low-order modes, can be significantly attenuated even with a thin layer of coating if the coating material is not too lossy. A thinner layer of coating is required for large attenuation of the low-order modes if the coating material is magnetic rather than dielectric. The Radar Cross Section (RCS) from an uncoated circular guide terminated by a perfect electric conductor was calculated and compared with available experimental data. It is confirmed that the interior irradiation contributes to the RCS. The equivalent-current method based on the geometrical theory of diffraction (GTD) was chosen for the calculation of the contribution from the rim diffraction. The RCS reduction from a coated circular guide terminated by a PEC are planned schemes for the experiments are included. The waveguide coated with a lossy magnetic material is suggested as a substitute for the corrugated waveguide

Wave attenuation and mode dispersion in a waveguide coated with lossy dielectric material

The modal attenuation constants in a cylindrical waveguide coated with a lossy dielectric material are studied as functions of frequency, dielectric constant, and thickness of the dielectric layer. A dielectric material best suited for a large attenuation is suggested. Using Kirchhoff's approximation, the field attenuation in a coated waveguide which is illuminated by a normally incident plane wave is also studied. For a circular guide which has a diameter of two wavelengths and is coated with a thin lossy dielectric layer (omega sub r = 9.1 - j2.3, thickness = 3% of the radius), a 3 dB attenuation is achieved within 16 diameters

Secure two-party quantum evaluation of unitaries against specious adversaries

We describe how any two-party quantum computation, specified by a unitary which simultaneously acts on the registers of both parties, can be privately implemented against a quantum version of classical semi-honest adversaries that we call specious. Our construction requires two ideal functionalities to garantee privacy: a private SWAP between registers held by the two parties and a classical private AND-box equivalent to oblivious transfer. If the unitary to be evaluated is in the Clifford group then only one call to SWAP is required for privacy. On the other hand, any unitary not in the Clifford requires one call to an AND-box per R-gate in the circuit. Since SWAP is itself in the Clifford group, this functionality is universal for the private evaluation of any unitary in that group. SWAP can be built from a classical bit commitment scheme or an AND-box but an AND-box cannot be constructed from SWAP. It follows that unitaries in the Clifford group are to some extent the easy ones. We also show that SWAP cannot be implemented privately in the bare model

Interpretation and the Constraints on International Courts

This paper argues that methodologies of interpretation do not do what they promise – they do not constrain interpretation by providing neutral steps that one can follow in finding out a meaning of a text – but nevertheless do their constraining work by being part of what can be described as the legal practice

La phylog\ue9nie des cercopithecin\ue9s encore en costruction.

Les cercopithecines (guenons et autres taxa corr\ue9l\ue9es) sont un groupe de singes africains qui se composent d'environ 36 r\ue9elles esp\ue8ces avec une \ue9volution et une phylog\ue9nie tr\ueas difficile \ue0 reconstruire. L\u2019approche scolaire a la tendance \ue0 proposer la clusterisation du groupe en question en deux: strictement arboricoles et terrestres. Avec la pr\ue9sente, nous analysons de fa\ue7on critique les diff\ue9rentes reconstructions phylog\ue9n\ue9tiques propos\ue9es aujourd\u2019hui tout en conduisant une analyse sur la base des aspects mol\ue9culaires, chromosomiques et \ue9cologiques des esp\ue8ces incluses dans le "groupe d'esp\ue8ces" actuellement reconnu. Cette approche multidisciplinaire inclue la morphologie, l'\ue9cologie r\ue9gionale ainsi que les r\ue9sultats des recherche s conduites dans les zones g\ue9ographiques d\u2019appartenance et d\ue9montre l'incoh\ue9rence e l\u2019insuffisance du point de vue traditionnel

L\u2019ibridazione interspecifica: evidenze e limiti di un fenomeno ancora da comprendere

L\u2019interesse per l\u2019aspetto evoluzionistico dell\u2019ibridazione interspecifica \ue8 cresciuto negli ultimi anni, a giudicare dalla mole di articoli e review pubblicati sull\u2019argomento. Fili conduttori di questi lavori sono la considerazione dell\u2019ibridazione avvenuta e la conseguente ricerca delle evidenze che la dimostrano, siano esse morfologiche o genetiche: quasi mai l\u2019evento di ibridazione viene messo in discussione, neppure quando le specie coinvolte sono caratterizzate da sbilanciamenti aneuploidi molto forti. Generalmente, l\u2019ibridazione tra specie riconosciute come distinte \ue8 impedita dall\u2019innescarsi di meccanismi d\u2019isolamento pre e postzigotici. Questa incompatibilit\ue0 ci porta a mettere in discussione la facilit\ue0 con cui lo status di ibrido sia stato stabilito in questi lavori. Scopo della presente review \ue8 quello di investigare il trend del fenomeno nel tempo e i metodi utilizzati per analizzarlo. Prendendo come punto di partenza proprio l\u2019approccio teorico di Dobzhansky, abbiamo analizzato criticamente la letteratura disponibile al riguardo, privilegiando le indagini effettuate sui mammiferi e, in modo particolare, sui primati, data la constatazione che anche minime evidenze di aneuploidia sono non vitali nell\u2019uomo. Il database che ne abbiamo ricavato ci ha permesso di verificare come l\u2019interesse nei confronti dell\u2019ibridazione sia cresciuto nel tempo e quanto il numero di specie soggette ad ibridazione sia aumentato. Tuttavia, nonostante l\u2019evoluzione delle tecniche, alcuni lavori hanno privilegiato l\u2019approccio morfologico: discriminante, ma non sufficientemente risolutivo. Gli studi che, invece, hanno investigato l\u2019aspetto genetico si sono limitati a ricercare i riarrangiamenti cromosomici che caratterizzano l\u2019ibrido (supposto). La definizione di buona specie \ue8 spesso aleatoria, in quanto frutto di concetti che rappresentano categorie mentali. Non nascondendo che l\u2019introgressione possa essere considerata un valido meccanismo di speciazione, non crediamo, tuttavia, che esso possa manifestarsi cos\uec facilmente in specie caratterizzate da profonde differenze genomiche. Riteniamo che ulteriori indagini \u2013 in particolare, mediante approcci come l\u2019ibridazione in situ miranti al confronto di ampie aree cromosomiche di omologia - siano necessarie per approfondire le nostre conoscenze su un fenomeno ancora in gran parte da comprendere

A crystallographic route to understand drug solubility: the case of 4- aminoquinoline antimalarials

Most Active Pharmaceutical Ingredients (API) can be prepared in various crystalline forms [1] displaying largely different physical/chemical properties and bioavailability. Salt formation represents the most common and simplest chemical way to modify the overall features but also the toxicity and biopharmaceutical availability of a drug substance. However, it is often unclear how and why the chemical and crystallographic characters can cooperate in determining these changes. We here face the problem from the perspective of the antiplasmodial drug piperaquine (PQ, C29H32Cl2N6) [2]. Being highly lipophilic, both neutral PQ and its commercial hydrogen phosphate tetrahydrate salt are poorly soluble in water, resulting in a reduced oral bioavailability. We synthesized five novel PQ salts and characterized them by both single crystal X\u2013ray diffraction methods and T-dependent (20 \u2013 50 \ubaC) UV\u2013Vis spectroscopy. Our aim was to explore possible relationships among non-covalent interaction networks in the crystals and measured solubilities. We also estimated changes in thermodynamic state functions related to the solvation process by DFT simulations, both in vacuo and in the solid state. We found that solubilities of PQ salts conform in most cases to the Hard and Soft Acid and Bases (HSAB) rules, i.e. less soluble compounds bear ions of comparable hardness. Crystal packing plays a far less important role, even though disorder-related entropic effects can influence the response of solubility to temperature. A possible take-home message is that intensive thermodynamic properties stem from a non-trivial cooperation several physicochemical effects. A first-principle understanding of the drug solubility cannot rely just on the description of the crystal packing, but must take into account the explicit evaluation of interaction energetics and pertinent electronic factors. [1] R. Hilfiker and M. von Raumer, Polymorphism in the Pharmaceutical Industry: Solid Form and Drug Development. 2019, Wiley-VCH, Weinheim (Germany). ISBN: 978-3-527-34040-8. [2] P. Sacchi, L. Loconte, G. Macetti, S. Rizzato and L. Lo Presti Crystal Growth Des. 2019. 19, 139