Inadequacies in the conventional treatment of the radiation field of moving sources

There is a fundamental difference between the classical expression for the retarded electromagnetic potential and the corresponding retarded solution of the wave equation that governs the electromagnetic field. While the boundary contribution to the retarded solution for the {\em potential} can always be rendered equal to zero by means of a gauge transformation that preserves the Lorenz condition, the boundary contribution to the retarded solution of the wave equation governing the {\em field} may be neglected only if it diminishes with distance faster than the contribution of the source density in the far zone. In the case of a source whose distribution pattern both rotates and travels faster than light {\em in vacuo}, as realized in recent experiments, the boundary term in the retarded solution governing the field is by a factor of the order of $R^{1/2}$ {\em larger} than the source term of this solution in the limit that the distance $R$ of the boundary from the source tends to infinity. This result is consistent with the prediction of the retarded potential that part of the radiation field generated by a rotating superluminal source decays as $R^{-1/2}$, instead of $R^{-1}$, a prediction that is confirmed experimentally. More importantly, it pinpoints the reason why an argument based on a solution of the wave equation governing the field in which the boundary term is neglected (such as appears in the published literature) misses the nonspherical decay of the field

Teratogenic effects of carbamazepine on embryonic eye development in pregnant mice

Background: Carbamazepine is an antiepileptic drug used widely for the treatment of epileptic seizures and neuropathic pain. Several malformations in humans, mainly neural tube defects, have been reported as a consequence of its use during pregnancy. The association between maternal use of carbamazepine and congenital eye malformations is not very well understood. Objective: The purpose of this study was to examine this association after intraperitoneal injection of carbamazepine during the period of organogenesis in mice. Methods: Balb/c timed-pregnant mice were divided into 4 experimental and control groups. Two experimental groups received daily intraperitoneal injections of 15mg/kg (group I) or 30mg/kg (group II) of carbamazepine on gestational days 6 to 15. Two control groups received normal saline or Tween 20 (polysorbate 20). Dams underwent Cesarean section on gestational day 18 and embryos were harvested. External examination for eye malformations, routine histological processing of malformed fetuses to study eye morphology, and skeletal staining were performed. Results: The mean weight and crown-rump of the fetuses in both experimental groups were significantly reduced compared with those of the control groups. Various malformations were detected such as brachygnathia, calvarial deformity, vertebral deformity, short tail, and brachydactyly. Premature opening of one or both eyes with mild to severe exophthalmos occurred in the 2 experimental groups. Deformed lens, retinal folds with undeveloped layers, and corneal folds with absence of surface epithelium were detected in both experimental groups. Conclusions: This study, to the best of our knowledge, showed for the first time that intraperitoneal administration of carbamazepine at clinically comparable doses during organogenesis can induce several eye malformations in mice. The implication of these results needs to be considered when carbamazepine is administered during human pregnancy. © 2010 Informa UK Ltd

Adsorption and dissociation of H<inf>2</inf> on Pd doped graphene-like SiC sheet

© 2016 Hydrogen Energy Publications LLCDoped porous SiC nanostructures with metallic atoms, nanoclusters and nanoparticles have been recognized as promising materials for hydrogen storage. With this regards transition metal elements are interesting impurities for use as doping. In view of this prospect, a theoretical approach based on density functional theory (DFT) was applied to study of the interaction between hydrogen molecule and a graphene-like SiC sheet doped with palladium atom. We have selected a single graphene-like SiC layer, due to its more surface charge polarization in comparison with pure graphene which makes possible remarkable interactions with adsorbed hydrogen molecules. In our study we have included two different configurations of H2 adsorption: 1) at the first state, hydrogen atoms after adsorption stretched and distance between H[sbnd]H atoms has increased but their chemical bond doesn't break. In this situation a physical adsorption occurred and the binding energy restricts applicable interests where it is appropriate for reversible hydrogen storage; 2) at the second situation, atoms of hydrogen molecule discrete from each other and adsorption occurred in a chemical manner. As instance the when a H2 molecule interact simultaneously with Pd atom and SiC nanosheet, it can be dissociated as in this case a hydrogen atom makes bond with Pd atom and the other can be adsorbed chemically on the SiC nanosheet surface. More details about adsorption mechanism are discussed it the context

ANALISA AGREGAT KASAR SEBAGAI VARIABEL BAHAN CAMPURAN BETON MENGGUNAKAN METODE SNI DAN ACI (Studi Kasus Beton Mutu K-275)

Penelitian ini dilakukan dengan maksud dan tujuan adalah untuk menganalisa dan membandingkan kuat tekan beton yang dapat dicapai menggunakan agregat kasar sumber Padang Ratu, Tegineneng dan Tanjungan. Selain itu juga untuk mengetahui kualitas agregat kasar yang bersumber dari daerah Padang Ratu, Tegineneng dan Tanjungan sebagai bahan campuran beton dengan metode SNI dan ACI. Untuk membandingkan nilai kuat tekan beton yang dihasilkan menggunakan agregat kasar yang bersumber dari daerah Padang Ratu, Tegineneng dan Tanjungan korelasinya terhadap pencapaian mutu beton K-275 atau setara dengan 22,825 Mpa. Penelitian ini menggunakan sampel Uji Silinder diameter 15 cm dan tinggi 30 cm. Pengujian dilakukan saat umur 7, 14, 21 dan 28 dan setiap umur terdiri dari 3 benda uji. Sehingga dibutuhkan 72 benda uji. Dengan 3 variasi penggunaan agregat kasar dari 3 quarry yaitu Tanjungan, Padang Ratu dan Tegineneng menggunakan metode SNI dan ACI. Hasil penelitian menunjukkan bahwa kualitas agregat mempengaruhi mutu beton yang dihasilkan. Hubungan kuat tekan beton dengan umur beton menunjukkan bahwa semakin bertambahnya umur beton, kuat tekan beton meningkat juga. Dari hasil penelitian, beton yang mencapai kuat tekan rencana adalah pada campuran beton  menggunakan agregat kasar Tanjungan dengan umur 28 hari yaitu : 23,10 Mpa (Metode ACI) dan 277,42 Kg/cm2 (Metode SNI)

Robust mutual synchronization in long spin Hall nano-oscillator chains

Mutual synchronization of N serially connected spintronic nano-oscillators increases their coherence by a factor $N$ and their output power by $N^2$. Increasing the number of mutually synchronized nano-oscillators in chains is hence of great importance for better signal quality and also for emerging applications such as oscillator-based neuromorphic computing and Ising machines where larger N can tackle larger problems. Here we fabricate spin Hall nano-oscillator chains of up to 50 serially connected nano-constrictions in W/NiFe, W/CoFeB/MgO, and NiFe/Pt stacks and demonstrate robust and complete mutual synchronization of up to 21 nano-constrictions, reaching linewidths of below 200 kHz and quality factors beyond 79,000, while operating at 10 GHz. We also find a square increase in the peak power with the increasing number of mutually synchronized oscillators, resulting in a factor of 400 higher peak power in long chains compared to individual nano-constrictions. Although chains longer than 21 nano-constrictions also show complete mutual synchronization, it is not as robust and their signal quality does not improve as much as they prefer to break up into partially synchronized states. The low current and low field operation of these oscillators along with their wide frequency tunability (2-28 GHz) with both current and magnetic fields, make them ideal candidates for on-chip GHz-range applications and neuromorphic computing.Comment: 9 Pages, 7 figure