Vibrational Excitons in CH-Stretching Fundamental and Overtone Vibrational Circular Dichroism Spectra

A set of vibrational circular dichroism (VCD) spectra in the CH-stretching fundamental region for about twenty compounds belonging to the class of essential oils was empirically analyzed by the use of a sort of vibrational exciton mechanism, involving three centers. Through a general formula applicable to many coupled dipole oscillators, the rotational strengths of the previously identified vibrational excitons are evaluated. The results are then critically reviewed by the use of recent ab initio methodology, as applied to selected molecules of the original set. Further insight is gained by model calculations adding up the contribution of the coupling between electric dipole moments associated with normal mode behavior and that of the polarizability from polarizable groups. The former part is responsible for the excitonic behavior of the VCD spectra. For the same selected molecules we have also investigated whether some excitonic behavior is taking place in the second overtone region, and have concluded that this is not the case

PMAS: The Potsdam Multi Aperture Spectrophotometer. II. The Wide Integral Field Unit PPak

PPak is a new fiber-based Integral Field Unit (IFU), developed at the Astrophysical Institute Potsdam, implemented as a module into the existing PMAS spectrograph. The purpose of PPak is to provide both an extended field-of-view with a large light collecting power for each spatial element, as well as an adequate spectral resolution. The PPak system consists of a fiber bundle with 331 object, 36 sky and 15 calibration fibers. The object and sky fibers collect the light from the focal plane behind a focal reducer lens. The object fibers of PPak, each 2.7 arcseconds in diameter, provide a contiguous hexagonal field-of-view of 74 times 64 arcseconds on the sky, with a filling factor of 60%. The operational wavelength range is from 400 to 900nm. The PPak-IFU, together with the PMAS spectrograph, are intended for the study of extended, low surface brightness objects, offering an optimization of total light-collecting power and spectral resolution. This paper describes the instrument design, the assembly, integration and tests, the commissioning and operational procedures, and presents the measured performance at the telescope.Comment: 14 pages, 21 figures, accepted at PAS

Guided Bone Regeneration with Application of Titanium Membrane (Clinical experience)

U implantologiji i parodontologiji se u svrhu kontrole regeneracije koštanoga tkiva rabe resorptivne i neresorptivne membrane.U ovome radu prikazana su iskustva dobivena uporabom neresorptivne titan neperforirane membrane. U slučajevima velikih koštanih defekata s namjerom ugradnje usadaka “Paraplant 2000” simultano smo upotrebljavali titan membrane kako bi se dobio koštani volumen odmah nakon ugradnje usadka u defekt. Fiksacija titan membrane provedena je s pomoću “Currasan” seta. Kod obrađenih i prikazanih slučajeva ustanovili smo opsežnu koštanu regeneraciju nakon 75 dana. Time i opravdanost uporabe titan membrane.Resorbable and non-resorbable membranes are used in implantology and periodontology for guided bone regeneration. This paper shows experience that has been gained from using non-resorbable titanium non-perforated membrane. In case of large bone defects with intention to place an implant “Paraplant 2000” we simultaneously use titanium membrane for building up bone volume immediately after positioning implant into the defect. Fixation of titanium membrane has been performed with “Currasan” fixation set. In the processed and presented cases we have determined significant volume of bone regeneration after 75 days which validate application of titanium membrane

Comparison of available measurements of the absolute fluorescence yield

The uncertainty in the absolute value of the fluorescence yield is still one of the main contributions to the total error in the reconstruction of the primary energy of ultra-energetic air showers using the fluorescence technique. A significant number of experimental values of the fluorescence yield have been published in the last years, however reported results are given very often in different units (photons/MeV or photons/m) and for different wavelength intervals. In this work we present a comparison of available results normalized to its value in photons/MeV for the 337 nm band at 800 hPa and 293 K. The conversion of photons/m to photons/MeV requires an accurate determination of the energy deposited by the electrons in the field of view of the experimental setup. We have calculated the energy deposition for each experiment by means of a detailed Monte Carlo simulation including when possible the geometrical details of the particular setup. Our predictions on deposited energy, as well as on some geometrical factors, have been compared with those reported by the authors of the corresponding experiments and possible corrections to the fluorescence yields are proposed.Comment: 29 pages, 5 figures Revised version submitted to Astroparticle Physic

Optimal light harvesting structures at optical and infrared frequencies

One-dimensional light harvesting structures with a realistic geometry nano-patterned on an opaque metallic film are optimized to render high transmission efficiencies at optical and infrared frequencies. Simple design rules are developed for the particular case of a slit-groove array with a given number of grooves that are symmetrically distributed with respect to a central slit. These rules take advantage of the hybridization of Fabry-Perot modes in the slit and surface modes of the corrugated metal surface. Same design rules apply for optical and infrared frequencies. The parameter space of the groove array is also examined with a conjugate gradient optimization algorithm that used as a seed the geometries optimized following physical intuition. Both uniform and nonuniform groove arrays are considered. The largest transmission enhancement, with respect to a uniform array, is obtained for a chirped groove profile. Such enhancement is a function of the wavelength. It decreases from 39% in the optical part of the spectrum to 15% at the long wavelength infrared.Comment: 13 pages, 5 figure

Development and Validation of the Mental Health Professionals\u27 Attitude Towards People Living with HIV/AIDS Scale (MHP-PLHIV-AS)

This study focused on the creation and validation of an instrument to measure mental health professionals\u27 attitudes towards people living with HIV/AIDS. Rasch analyses (Rash, 1960, 1980) provided evidence to support a two-dimensional (societal and personal dimensions) measurement of this attitude construct

Electron focusing, mode spectroscopy and mass enhancement in small GaAs/AlGaAs rings

A new electron focusing effect has been discovered in small single and coupled GaAs/AlGaAs rings. The focusing in the single ring is attributed solely to internal orbits. The focusing effect allows the ring to be used as a small mass spectrometer. The focusing causes peaks in the magnetoresistance at low fields, and the peak positions were used to study the dispersion relation of the one-dimensional magnetoelectric subbands. The electron effective mass increases with the applied magnetic field by a factor of $50$, at a magnetic field of $0.5T$. This is the first time this increase has been measured directly. General agreement obtains between the experiment and the subband calculations for straight channels.Comment: 13 pages figures are available by reques

Adubação com compostos orgânicos e cobertura verde do solo em pomar de tangerineiras sob cultivo orgânico.

201