Kvazielastično raspršenje elektrona na 4He između 328 i 725 MeV

4He(e,e˘) cross section data at 328, 365 and 725 MeV have been analyzed using the quasi-free scattering (QFS) model of Lightbody and O\u27Connell. The QFS model provides an improved description of the shape and magnitude of the cross section data when compared with plane-wave impulse approximation calculations, particularly at higher values of the electron energy loss. Although the nucleon separation energy is about 20 MeV in 4He, the best QFS results are obtained for a 6 MeV value.Podaci za udarni presjek 4He na energijama od 328, 365 i 725 MeV analizirani su koristeći model kvazi-slobodnog raspršenja Lightbodyja i O\u27Connella. Model omogućava poboljšan opis oblika i iznosa udarnog presjeka u odnosu na rezultate dobivene u aproksimaciji impulsa ravnih valova. To naročito vrijedi za veće gubitke energije elektrona. Iako je energija separacije oko 20 MeV u 4He, najbolji rezultati dobiveni su za 6 MeV-a

Izrazi za zakrivljenost u općoj teoriji relativnosti

A clear physical description of a variety of spacetime geometries is provided in terms of the various connection coefficients and curvature-related tensors. The affine connection coefficients, the Riemann curvature tensor, Ricci tensor, scalar curvature and Einstein tensor, and associated discussion is provided for flat spacetime, the Schwarzschild geometry, the Morris-Thorne wormhole geometry, the FriedmannRobertson-Walker geometry, and a static spherical geometry.Daje se jasan opis niza prostorno-vremenskih geometrija preko veznih koeficijenata i tenzora zakrivljenosti koji se rabe u teoriji. Navode se afini vezni koeficijenti, Riemannov tenzor zakrivljenosti, Riccijev tenzor, skalarna zakrivljenost i Einsteinov tenzor, i oni se raspravljaju za ravan prostor, Schwarzschildovu geometriju, MorrisThorneovu geometriju crvotočina, te Friedmann-Robertson-Walkerovu i statičku sfernu geometriju

Radiotherapy Dose Optimization in Target Tissues Using Internal Radiation-Generating Devices and Microspheres

Preferentially delivering ionizing radiation to target tissues during radiotherapy procedures is investigated using internal radiation-generating devices and microspheres loaded with radioactive material. This chapter presumes the existence of internal radiation-generating devices and develops their requisite characteristics to permit the selective irradiation of tumors. The feasibility of disrupting a tumor’s vascular structure is also investigated. Calculated absorbed dose profiles for both approaches demonstrate that dose can be successfully localized in a target tissue while minimizing the delivery to healthy tissue

Kvazielastično raspršenje elektrona na 4He između 328 i 725 MeV

4He(e,e˘) cross section data at 328, 365 and 725 MeV have been analyzed using the quasi-free scattering (QFS) model of Lightbody and O\u27Connell. The QFS model provides an improved description of the shape and magnitude of the cross section data when compared with plane-wave impulse approximation calculations, particularly at higher values of the electron energy loss. Although the nucleon separation energy is about 20 MeV in 4He, the best QFS results are obtained for a 6 MeV value.Podaci za udarni presjek 4He na energijama od 328, 365 i 725 MeV analizirani su koristeći model kvazi-slobodnog raspršenja Lightbodyja i O\u27Connella. Model omogućava poboljšan opis oblika i iznosa udarnog presjeka u odnosu na rezultate dobivene u aproksimaciji impulsa ravnih valova. To naročito vrijedi za veće gubitke energije elektrona. Iako je energija separacije oko 20 MeV u 4He, najbolji rezultati dobiveni su za 6 MeV-a

Finite-Difference and Pseudospectral Time-Domain Methods Applied to Backwards-Wave Metamaterials

Backwards-wave (BW) materials that have simultaneously negative real parts of their electric permittivity and magnetic permeability can support waves where phase and power propagation occur in opposite directions. These materials were predicted to have many unusual electromagnetic properties, among them amplification of the near-field of a point source, which could lead to the perfect reconstruction of the source field in an image [J. Pendry, Phys. Rev. Lett. \textbf{85}, 3966 (2000)]. Often systems containing BW materials are simulated using the finite-difference time-domain technique. We show that this technique suffers from a numerical artifact due to its staggered grid that makes its use in simulations involving BW materials problematic. The pseudospectral time-domain technique, on the other hand, uses a collocated grid and is free of this artifact. It is also shown that when modeling the dispersive BW material, the linear frequency approximation method introduces error that affects the frequency of vanishing reflection, while the auxiliary differential equation, the Z transform, and the bilinear frequency approximation method produce vanishing reflection at the correct frequency. The case of vanishing reflection is of particular interest for field reconstruction in imaging applications.Comment: 9 pages, 8 figures, accepted by IEEE Transactions on Antennas and Propagatio

Nastanak centripetalnog ubrzanja u Frenet–Serretovom sustavu

A clear physical description of a particle\u27s motion in terms of the components of its acceleration is obtained if the trajectory is described in terms of the Frenet-Serret frame. Within this frame, centripetal acceleration emerges as a natural consequence of a particle\u27s motion.Ako se putanja čestice opisuje u Frenet–Serretovom sustavu, postiže se jasan fizički opis njenog gibanja preko komponenata njenog ubrzanja. U tom se sustavu centripetalno ubrzanje javlja kao prirodna posljedica gibanja čestice

Izrazi za zakrivljenost u općoj teoriji relativnosti

A clear physical description of a variety of spacetime geometries is provided in terms of the various connection coefficients and curvature-related tensors. The affine connection coefficients, the Riemann curvature tensor, Ricci tensor, scalar curvature and Einstein tensor, and associated discussion is provided for flat spacetime, the Schwarzschild geometry, the Morris-Thorne wormhole geometry, the FriedmannRobertson-Walker geometry, and a static spherical geometry.Daje se jasan opis niza prostorno-vremenskih geometrija preko veznih koeficijenata i tenzora zakrivljenosti koji se rabe u teoriji. Navode se afini vezni koeficijenti, Riemannov tenzor zakrivljenosti, Riccijev tenzor, skalarna zakrivljenost i Einsteinov tenzor, i oni se raspravljaju za ravan prostor, Schwarzschildovu geometriju, MorrisThorneovu geometriju crvotočina, te Friedmann-Robertson-Walkerovu i statičku sfernu geometriju

Nastanak centripetalnog ubrzanja u Frenet–Serretovom sustavu

A clear physical description of a particle\u27s motion in terms of the components of its acceleration is obtained if the trajectory is described in terms of the Frenet-Serret frame. Within this frame, centripetal acceleration emerges as a natural consequence of a particle\u27s motion.Ako se putanja čestice opisuje u Frenet–Serretovom sustavu, postiže se jasan fizički opis njenog gibanja preko komponenata njenog ubrzanja. U tom se sustavu centripetalno ubrzanje javlja kao prirodna posljedica gibanja čestice

Single Band Antenna For Ism Remote Controls

Disclosed herein is a novel antenna device design that could be applied in hand-held radio band remote controls for devices. Accordingly, the antenna structure uses a unique ground cut-out and capacitive coupling to the ground structure on a PCB that includes a button located on the other side of the antenna. The design utilizes the close proximity of the battery and battery terminal as part of the antenna structure and their relative placement could be tuned to maintain performance. Further, the selection of inductive chokes for the button control pins allows the antenna to continue to operate without significant degradation to radiated efficiency. The design includes comparable performance while in free space as well as when hand-held. Because of the exact placement of the radiating structures, hand holding does not cause the antenna center frequency to detune as seen with other designs