An antimicrobial peptide that inhibits translation by trapping release factor trap.

Apidaecin (Api) belongs to the group of proline-rich antimicrobial peptides (PrAMPs), which are produced by insects and mammals and protect the host from bacterial infection. PrAMPs enter the bacterial cell, bind to the ribosome, and inhibit protein synthesis. Biochemical characterization and recent high-resolution crystal structures have shown that most PrAMPs obstruct the nascent peptide exit tunnel and the peptidyl transferase center in the ribosome and block the initiation step of translation. Despite the lack of the structural information about the Api-bound ribosome, its similarities with the other PrAMPs suggested that Api also inhibits translation initiation. However, our toeprinting experiments in a cell free translation system revealed that Api does not inhibit initiation but, instead, stalls the ribosome at the stop codon. Isolation of Api-resistant E. coli mutants with alterations in class-1 release factors RF1 and RF2, indicated that Api may interfere with the functions of these factors and/or their association with the ribosome. Consistently, our high-resolution cryo-EM structures of ribosomes complexed with Api showed that Api establishes interactions with the ribosomal exit tunnel and with the functionally important conserved GGQ motif of RF1. Furthermore, kinetic studies revealed that Api does not prevent the release of the nascent peptide chain but impedes the dissociation of RF from its binding site in the ribosome. By trapping RF1 and RF2 in the ribosome, Api leads to depletion of free class-1 RFs in the cell, resulting in inhibition of protein synthesis and cell growth arrest. Importantly, the Api-dependent depletion of RFs facilitates premature stop codon read-through. We envision the possibility that similar trapping of RFs on eukaryotic ribosomes could aid in relieving the effects of human genetic diseases caused by premature stop-codons

Photonuclear Reactions of Three-Nucleon Systems

We discuss the available data for the differential and the total cross section for the photodisintegration of $^3$He and $^3$H and the corresponding inverse reactions below $E_\gamma = 100$ MeV by comparing with our calculations using realistic $NN$ interactions. The theoretical results agree within the errorbars with the data for the total cross sections. Excellent agreement is achieved for the angular distribution in case of $^3$He, whereas for $^3$H a discrepancy between theory and experiment is found.Comment: 11 pages (twocolumn), 12 postscript figures included, uses psfig, RevTe

Faddeev Calculations of Proton-Deuteron Radiative Capture with Exchange Currents

pd capture processes at various energies have been analyzed based on solutions of 3N-Faddeev equations and using modern NN forces. The application of the Siegert theorem is compared to the explicit use of $\pi$- and $\rho$-like exchange currents connected to the AV18 NN interaction. Overall good agreement with cross sections and spin observables has been obtained but leaving room for improvement in some cases. Feasibility studies for 3NF's consistently included in the 3N continuum and the 3N bound state have been performed as well.Comment: Minor changes in notation, ps files for figure

Analysis of signal integrity in hybrid microelectronic circuits with use of the FDTD Method

W opracowaniu zaprezentowano zastosowanie metody skończonych różnic czasowych do analizy integralności sygnałów w wielokrotnych układach ścieżek mikroelektronicznych układów hybrydowych. Wykorzystując program MATHCAD opracowano algorytmy pozwalające na numeryczne rozwiązanie równania telegrafistów dla dowolnego bezstratnego układu przewodników. Zaprezentowane wyniki obliczeń dla wybranych konfiguracji ścieżek wykonanych w technologii grubowarstwowej, zweryfikowano doświadczalnie.The application of the Finite Difference Time Domain method for analysis of signal integrity in conductive path systems is presented in the paper. The algorithm allowing one to numerically solve of telegraph equations for any lossless path system on the basis of the Mathcad program was developed. The procedures elaborated with use of FDTD method enable analyzing the propagation of electrical signals in a selected system of paths with a specified input function shape for selected resistances loading the path system. The problems of signal integrity in planar circuits are presented in the introduction of this paper. Section 2 contains the theoretical basis of application of the Finite Difference Time Domain method to solving the telegraph equation. The basic relations and conditions allowing obtaining the calculation convergence for single and multiple path systems are also presented. The results of calculations and measurements for selected test circuits are included in Section 3. The influence of changes of path configuration and parameters of the test signal on its propagation process in mutual coupled paths was analyzed during investigations. The obtained good agreement of the calculation and measurements results confirmed the correctness of the elaborated algorithms and procedures

Current higher harmonics generated by compact fluorescent lamps supplied with sinusoidal and distorted voltage

Tematyka publikacji dotyczy problemu generowania wyższych harmonicznych prądu przez kompaktowe fluorescencyjne źródła światła. W opracowaniu przeanalizowano zmiany poziomu harmonicznych prądu generowanych przez tego typu odbiorniki w sytuacji gdy zasilano je napięciem sinusoidalnym i odkształconym. Do generacji przebiegów napięcia zasilającego w trakcie badań Kwykorzystano, stabilne programowalne źródło zasilania NetWave firmy EMTest. Uzyskane dzięki temu urządzeniu napięcia miały stabilne niezmienne parametry w czasie. trwania badań.The problem of generation of current higher harmonics by compact fluorescent light sources is described in this paper. The above-mentioned light sources were supplied by a sinusoidal voltage with THD equal to 0.1% then by a distorted voltage with THD equal to 6.58%. Both voltages were generated by a NetWave device from the EMTest. Such equipment guarantees the stable parameters during tests. The compact fluorescent lamps (9 W of nominal power) were used in the conducted tests. They were from three different manufacturers marked as A, B and C. The specifications of the tested lamps are presented in Tab. 1. The characteristic of the examined fluorescent lamps was included in the paper for two cases. In the first one, each lamp was supplied by a sinusoidal voltage. The obtained results are presented in Tabs. 2 and 3 as well as in Fig. 4. The next step was group operation of lamps (A1, A1+A2 and A1+A2+A3) manufactured by the same A factory and (A1+B1+ C1) manufactured by A, B and C factories. The results of investigations are presented in Tab. 4 and Figs. 5 and 6. In the second case, the same configurations of fluorescent lamps were supplied by a distorted voltage. The results are illustrated in Tabs. 5, 6 and 7 as well as in Figs. 7, 8 and 9

Research of electromagnetic radiated disturbances in frequency range from 30 to 300 MHz on example of LED lamps

Artykuł tematycznie jest związany z zagadnieniami kompatybilności elektromagnetycznej. Zostały w nim zamieszczone wyniki badań zaburzeń elektromagnetycznych promieniowanych, generowanych przez wybrane lampy LED. Badania przeprowadzono w dwóch etapach. W pierwszym scharakteryzowano każdą badana lampę ze względu na wartość generowanych zaburzeń elektromagnetycznych. Uzyskane wyniki odniesiono do dopuszczalnych limitów określonych w normie PN-EN 55015:2013. Natomiast w drugim etapie powiązano uzyskane wyniki z analizą prądu pobieranego przez badane lampy. Te działania pozwoliły określić przyczynę emitowanych zaburzeń. Badania zostały przeprowadzone w specjalistycznym laboratorium EMC, w którym pomiar emisji zaburzeń wykonywany jest w sposób automatyczny przy pomocy aparatury pomiarowej firmy Rohde&Shwarz.The article is thematically related to the electromagnetic compatibility problems. It contains the results of the research on electromagnetic radiated disturbances generated by selected LED lamps. The research was carried out in two stages. In the first one, each tested lamp was characterized in relation to the value of generated electromagnetic disturbances. The obtained results were referred to the permissible limits specified in the PN-EN 55015:2013 standard. However, in the second stage, the obtained results were combined with the analysis of the current consumed by the tested lamps. These tests allowed to determine the cause of the emitted disturbances. The tests were carried out in a specialized EMC laboratory where the measurements of disturbances is carried out automatically using Rohde & Schwarz measuring equipment

Research of radioelectric conductive disturbances generated by LED lamps

Artykuł zawiera wyniki badań zaburzeń radioelektrycznych przewodzonych generowanych przez lampy LED. We wstępie artykułu zaprezentowano informacje na temat zaburzeń elektromagnetycznych, ich rodzajów oraz przyczyn generowania zaburzeń przez lampy LED. Natomiast w następnych rozdziałach zamieszczono wyniki badań. Lampy LED przebadano na stanowisku pomiarowym znajdującym się Laboratorium kompatybilności elektromagnetycznej Politechniki Rzeszowskiej. Podczas badań wykorzystano sprzęt pomiarowy firmy Rohde&Schwarz. Badania przeprowadzono zgodnie z procedurą badań określoną w z normie PN–EN 55015. Uzyskane wyniki pozwoliły scharakteryzować badane lampy LED ze względu na wartość generowanych zaburzeń przewodzonych, a następnie porównać z rozwiązaniami układowymi zasilaczy, stosowanymi w tych lampach.The test results of radioelectric conductive disturbances generated by led lamps have been presented in this paper. The introduction includes information about types of electromagnetic disturbances and reasons of their generation by LED lamps as well as in the next chapters the results of research were presented and discussed. The LED lamps were tested on measuring stand in EMC Laboratory at Rzeszów University of Technology using Rohde&Schwarz equipment. The measurements were conducted in accordance with PN–EN 55015 standard. The obtained results allowed to characterize of tested lamps in relation to value of generated conductive disturbances and next to compare with supply solutions used in those devices