Energy in one dimensional linear waves in a string

We consider the energy density and energy transfer in small amplitude, one-dimensional waves on a string, and find that the common expressions used in textbooks for the introductory physics with calculus course give wrong results for some cases, including standing waves. We discuss the origin of the problem, and how it can be corrected in a way appropriate for the introductory calculus based physics course.Comment: 5 page

An off-shell I.R. regularization strategy in the analysis of collinear divergences

We present a method for the analysis of singularities of Feynman amplitudes based on the Speer sector decomposition of the Schwinger parametric integrals combined with the Mellin-Barnes transform. The sector decomposition method is described in some details. We suggest the idea of applying the method to the analysis of collinear singularities in inclusive QCD cross sections in the mass-less limit regularizing the forward amplitudes by an off-shell choice of the initial particle momenta. It is shown how the suggested strategy works in the well known case of the one loop corrections to Deep Inelastic Scattering.Comment: 25 pages, 3 figure

Second harmonic generation on self-assembled GaAs/Au nanowires with thickness gradient

Here we investigated the SH generation at the wavelength of 400 nm (pump laser at 800 nm, 120 fs pulses) of a "metasurface" composed by an alternation of GaAs nano-grooves and Au nanowires capping portions of flat GaAs. The nano-grooves depth and the Au nanowires thickness gradually vary across the sample. The samples are obtained by ion bombardment at glancing angle on a 150 nm Au mask evaporated on a GaAs plane wafer. The irradiation process erodes anisotropically the surface, creating Au nanowires and, at high ion dose, grooves in the underlying GaAs substrate (pattern transfer). The SHG measurements are performed for different pump linear polarization angle at different positions on the "metasurface" in order to explore the regions with optimal conditions for SHG efficiency. The pump polarization angle is scanned by rotating a half-wave retarder plate. While the output SH signal in reflection is analyzed by setting the polarizer in s or p configuration in front of the detector. The best polarization condition for SHG is obtained in the configuration where the pump and second harmonic fields are both p polarized, and the experiments show a SH polarization dependence of the same symmetry of bulk GaAs. Thus, the presence of gold contributes only as field localization effect, but do not contributes directly as SH generator

A Finite Element Study of Electromagnetic Riveting

Electromagnetic riveting, used in some aerospace assembly processes, involves rapid deformation, leading to the finished rivet configuration. Analysis of this process is described for the case of an aluminum rivet joining typical aluminum structural elements. The analysis is based on a finite element method that includes the effects of heating, due to rapid plastic deformation of the material, on the material properties. Useful details of material deformation and thermal history and the final rivet and structure configuration and states of stress and strain are obtained. These results have significant implications in the design, implementation, and improvement of practical fastening processes in the aerospace industry

Romány Wolfganga Koeppena: angažovaná literatura a experimentální próza

Tato diplomová práce se zabývá poválečnou románovou trilogií německého spisovatele Wolfganga Koeppena (1906-1996): Tauben im Gras (1951), Das Treibhaus (1953) a Der Tod in Rom (1954). V první části podává práce nástin politicko-kulturního vývoje Německa v letech 1945-1965, s hlavním důrazem na padesátá léta. V této době prožívá země hospodářský zázrak a Němcům se vrací ztracené sebevědomí. Zároveň se ovšem ukazuje, že vize zcela nového počátku ztroskotala a Adenauerova konzervativní politika navrací Německo do vyježděných kolejí předválečného období. Od naléhavých politických otázek roku 1945 se zájem Němců obrací po výtce k zajištění vlastního blahobytu, měšťáckého pohodlí. Hrůzy války se zdají být zapomenuty a namísto prožitku "kolektivní viny" přichází "kolektivní ztráta paměti". Tato zásadní proměna nezůstala nepovšimnuta. Kriticky ji reflektovali zejména mladí spisovatelé sdružení kolem Skupiny 47. Mimo jejich řady a de facto na okraji dobového literárního dění vyslovuje svůj hlasitý protest proti poválečnému směřování německé společnosti také Wolfgang Koeppen. V následující části, která tvoří vlastní jádro celé práce, jsou postupně analyzovány zmíněné romány v kontextu doby svého vzniku i celku autorova díla. Leitmotivem všech tří románů jsou přitom pocity vykořeněnosti a bezvýsledného tápání lidí...This dissertation discusses the post-war trilogy of the German writer Wolfgang Koeppen (1906-1996): Tauben im Gras (1951), Das Treibhaus (1953) and Der Tod in Rom (1954). The first part of this paper gives a political-cultural concise of the years 1945-1965, with an emphasis on the fifties. At that time Germany goes through the process of the economic-mirage and according to this the Germans get back their lost self-assurance. By the same mail is increasingly obvious, that the vision of a complete beginning failed and that the conservative policy of Adenauer follows the beaten track of the pre-war period. From urgent political questions of the year 1945 the German interest turns over to security their own prosperity, middleclass comfort. The horrors of war seem to be forgotten and instead of the "collective guilt" comes the "collective amnesia". This fundamental change didn't stay unnoticed. A critical reflection happend mainly through the young authors united in the Gruppe 47. Beside their line and on the edge of the contemporary literary events Wolfgang Koeppen delivers his loud protest against the post-war development of the German society. In the following part, which sets up the crux of the whole paper, is given an analysis of the individual novels in the context of the time of their appearance and the...Ústav germánských studiíInstitute of Germanic StudiesFaculty of ArtsFilozofická fakult

A deep-learning sequence-based method to predict protein stability changes upon genetic variations

Several studies have linked disruptions of protein stability and its normal functions to disease. Therefore, during the last few decades, many tools have been developed to predict the free energy changes upon protein residue variations. Most of these methods require both sequence and structure information to obtain reliable predictions. However, the lower number of protein structures available with respect to their sequences, due to experimental issues, drastically limits the application of these tools. In addition, current methodologies ignore the antisymmetric property characterizing the thermodynamics of the protein stability: a variation from wild-type to a mutated form of the protein structure (XW→XM) and its reverse process (XM→XW) must have opposite values of the free energy difference (ΔΔGWM=−ΔΔGMW). Here we propose ACDC-NN-Seq, a deep neural network system that exploits the sequence information and is able to incorporate into its architecture the antisymmetry property. To our knowledge, this is the first convolutional neural network to predict protein stability changes relying solely on the protein sequence. We show that ACDC-NN-Seq compares favorably with the existing sequence-based methods

Magnetic loss analysis in coaxial magnetic gears

This paper proposes a procedure for computing magnetic losses in coaxial magnetic gears. These magnetic structures are made of permanent magnets and ferromagnetic poles in relative motion transferring torque between two shafts in a contactless way. The loss computation in magnetic materials is crucial to define the system performance. The flux distribution inside the iron parts is computed by means of the finite element method and a model of iron losses taking into account the rotational nature of the flux loci is applied. The procedure highlights where the major loss sources are present and gives the opportunity to evaluate some corrective measures to reduce their effects. Particular attention is devoted to the 2D modeling in presence of permanent magnets segmentatio

Critical boron-doping levels for generation of dislocations in synthetic diamond

Defects induced by boron doping in diamond layers were studied by transmission electron microscopy. The existence of a critical boron doping level above which defects are generated is reported. This level is found to be dependent on the CH4 /H2 molar ratios and on growth directions. The critical boron concentration lied in the 6.5–17.0 X 10 20 at/cm3 range in the direction and at 3.2 X 1021 at/cm 3 for the one. Strain related effects induced by the doping are shown not to be responsible. From the location of dislocations and their Burger vectors, a model is proposed, together with their generation mechanism.6 page

The Italian Sensorimotor Norms: Perception and action strength measures for 959 words

Neuroscience research has provided evidence that semantic information is stored in a distributed brain network involved in sensorimotor and linguistic processing. More specifically, according to the embodied cognition accounts, the representation of concepts is deemed as grounded in our bodily states. For these reasons, normative measures of words should provide relevant information about the extent to which each word embeds perceptual and action properties. In the present study, we collected ratings for 959 Italian nouns and verbs from 398 volunteers, recruited via an online platform. The words were mostly taken from the Italian adaptation of the Affective Norms for English Words (ANEW). A pool of 145 verbs was added to the original set. All the words were rated on 11 sensorimotor dimensions: six perceptual modalities (vision, audition, taste, smell, touch, and interoception) and five effectors (hand-arm, foot-leg, torso, mouth, head). The new verbs were also rated on the ANEW dimensions. Results showed good reliability and consistency with previous studies. Relations between perceptual and motor dimensions are described and interpreted, along with relations between the sensorimotor and the affective dimensions. The currently developed dataset represents an important novelty, as it includes different word classes, i.e., both nouns and verbs, and integrates ratings of both sensorimotor and affective dimensions, along with other psycholinguistic parameters; all features only partially accomplished in previous studies

Connection between the Slave-Particles and X-Operators Path-Integral Representations. a New Perturbative Approach

In the present work it is shown that the family of first-order Lagrangians for the t-J model and the corresponding correlation generating functional previously found can be exactly mapped into the slave-fermion decoupled representation. Next, by means of the Faddeev-Jackiw symplectic method, a different family of Lagrangians is constructed and it is shown how the corresponding correlation generating functional can be mapped into the slave-boson representation. Finally, in order to define the propagation of fermion modes we discuss two alternative ways to treat the fermionic sector in the path-integral formalism for the t-J model.Comment: 27 pages, latex, no figures(to be published in Journal of Physics A:Mathematical and General