Nonlinear dynamics in superlattices driven by high frequency ac-fields

We investigate the dynamical processes taking place in nanodevices driven by high-frequency electromagnetic fields. We want to elucidate the role of different mechanisms that could lead to loss of quantum coherence. Our results show how the dephasing effects of disorder that destroy after some periods coherent oscillations, such as Rabi oscillations, can be overestimated if we do not consider the electron-electron interactions that can reduce dramatically the decoherence effects of the structural imperfections. Experimental conditions for the observation of the predicted effects are discussed.Comment: REVTEX (8 pages) and 4 figures (Postscript

Massive scalar field near a cosmic string

The $\zeta$ function of a massive scalar field near a cosmic string is computed and then employed to find the vacuum fluctuation of the field. The vacuum expectation value of the energy-momentum tensor is also computed using a point-splitting approach. The obtained results could be useful also for the case of self-interacting scalar fields and for the finite-temperature Rindler space theory.Comment: 15 pages, standard LaTeX, no figures. Reference [14] correcte

Thermal partition function of photons and gravitons in a Rindler wedge

The thermal partition function of photons in any covariant gauge and gravitons in the harmonic gauge, propagating in a Rindler wedge, are computed using a local $\zeta$-function regularization approach. The correct Planckian leading order temperature dependence $T^4$ is obtained in both cases. For the photons, the existence of a surface term giving a negative contribution to the entropy is confirmed, as earlier obtained by Kabat, but this term is shown to be gauge dependent in the four-dimensional case and, therefore is discarded. It is argued that similar terms could appear dealing with any integer spin $s\geq 1$ in the massless case and in more general manifolds. Our conjecture is checked in the case of a graviton in the harmonic gauge, where different surface terms also appear, and physically consistent results arise dropping these terms. The results are discussed in relation to the quantum corrections to the black hole entropy.Comment: 29 pages, RevTeX, no figures. Minor errors corrected and a few comments changed since first submission. To be published on Phys.Rev.

Full configuration interaction approach to the few-electron problem in artificial atoms

We present a new high-performance configuration interaction code optimally designed for the calculation of the lowest energy eigenstates of a few electrons in semiconductor quantum dots (also called artificial atoms) in the strong interaction regime. The implementation relies on a single-particle representation, but it is independent of the choice of the single-particle basis and, therefore, of the details of the device and configuration of external fields. Assuming no truncation of the Fock space of Slater determinants generated from the chosen single-particle basis, the code may tackle regimes where Coulomb interaction very effectively mixes many determinants. Typical strongly correlated systems lead to very large diagonalization problems; in our implementation, the secular equation is reduced to its minimal rank by exploiting the symmetry of the effective-mass interacting Hamiltonian, including square total spin. The resulting Hamiltonian is diagonalized via parallel implementation of the Lanczos algorithm. The code gives access to both wave functions and energies of first excited states. Excellent code scalability in a parallel environment is demonstrated; accuracy is tested for the case of up to eight electrons confined in a two-dimensional harmonic trap as the density is progressively diluted and correlation becomes dominant. Comparison with previous Quantum Monte Carlo simulations in the Wigner regime demonstrates power and flexibility of the method.Comment: RevTeX 4.0, 18 pages, 6 tables, 9 postscript b/w figures. Final version with new material. Section 6 on the excitation spectrum has been added. Some material has been moved to two appendices, which appear in the EPAPS web depository in the published versio

Ambiguity in the evaluation of the effective action on the cone

An ambiguity in the computation of the one-loop effective action for fields living on a cone is illustrated. It is shown that the ambiguity arises due to the non-commutativity of the regularization of ultraviolet and (conical) boundary divergencies.Comment: REVTeX file, 10 pages. Comments on recent papers have been adde

Role of causality in ensuring unconditional security of relativistic quantum cryptography

The problem of unconditional security of quantum cryptography (i.e. the security which is guaranteed by the fundamental laws of nature rather than by technical limitations) is one of the central points in quantum information theory. We propose a relativistic quantum cryptosystem and prove its unconditional security against any eavesdropping attempts. Relativistic causality arguments allow to demonstrate the security of the system in a simple way. Since the proposed protocol does not employ collective measurements and quantum codes, the cryptosystem can be experimentally realized with the present state-of-art in fiber optics technologies. The proposed cryptosystem employs only the individual measurements and classical codes and, in addition, the key distribution problem allows to postpone the choice of the state encoding scheme until after the states are already received instead of choosing it before sending the states into the communication channel (i.e. to employ a sort of ``antedate'' coding).Comment: 9 page

Comparing migration in Britain and Australia: Harmonisation through use of age-time plans

Differences in the way migration is measured impede cross-national comparisons of internal migration. In this paper we utilise age-time diagrams to elucidate these problems for Australia and the United Kingdom and present solutions which generate time series of interregional migration for the two countries, harmonised with respect to age-time plans. We achieve this through estimation of the numbers of migration transitions (Australia) or migration events (Britain) for common age-period-cohort (APC) spaces. We derive appropriate population stocks for computation of transition probabilities or occurrence-exposure rates. In the final section of the paper we present a series of migration-intensity calculations based on varying combinations of period-cohort, period-age, and age-period-cohort perspectives, to demonstrate the significance of the variations, and the errors that can arise without harmonisation

Distinct Mechanisms for Ctr1-mediated Copper and Cisplatin Transport

The Ctr1 family of integral membrane proteins is necessary for high affinity copper uptake in eukaryotes. Ctr1 is also involved in cellular accumulation of cisplatin, a platinum-based anticancer drug. Although the physiological role of Ctr1 has been revealed, the mechanism of action of Ctr1 remains to be elucidated. To gain a better understanding of Ctr1-mediated copper and cisplatin transport, we have monitored molecular dynamics and transport activities of yeast Saccharomyces cerevisiae Ctr1 and its mutant alleles. Co-expression of functional Ctr1 monomers fused with either cyan or yellow fluorescent protein resulted in fluorescence resonance energy transfer (FRET), which is consistent with multimer assembly of Ctr1. Copper near the Km value of Ctr1 enhanced FRET in a manner that correlated with cellular copper transport. In vitro cross-linking of Ctr1 confirmed that copper-induced FRET reflects conformational changes within pre-existing Ctr1 complexes. FRET assays in membrane-disrupted cells and protein extracts showed that intact cell structure is necessary for Ctr1 activity. Despite Ctr1-dependent cellular accumulation, cisplatin did not change Ctr1 FRET nor did it attenuate copper-induced FRET. A Ctr1 allele defective in copper transport enhanced cellular cisplatin accumulation. N-terminal methionine-rich motifs that are dispensable for copper transport play a critical role for cisplatin uptake. Taken together, our data reveal functional roles for structural remodeling of the Ctr1 multimeric complex in copper transport and suggest distinct mechanisms employed by Ctr1 for copper and cisplatin transport

PENGGUNAAN TEPUNG LIMBAH LABU KUNING DALAM RANSUM TERHADAP PENAMPILAN PRODUKSI AYAM RAS PETELUR

THE EFFECT OF PUMPKIN WASTE MEAL IN LAYING HEN FEED ON PERFORMANS PRODUCTION. This research was to find out the use of pumpkin waste meal on performance in the production of laying hens. The purpose of this research was to observe the effect of the use of pumpkin waste meal performance in the production of feed for laying hens. A total of 100 MB 402 laying hens from 42 week of age were randomly alloted to four dietary treatments with 5 replication groups of 4 hens. Dietary treatment were; basal diet (R0), basal diet 98% + 2% WCP (R1), basal diet 96% + 4% WCP (R2), basal diet 94% + 6% WCP (R3), basal diet 92% + 8% WCP (R4). The variable were the feed Consumption, hen day production, feed conversion. Data was analyzed with completely randomized Design ( CRD ). The addition of in the feed was not influenced significantly (P > 0,05) to the feed consumption, hen day production, feed conversion. Based on the research that is done it can be concluted that the use of waste carrot pumpkins in the feed at the level of 8% show no significantly different result on the feed consumption, hen day production, feed conversion. Keyword : Pumpkin waste meal, performance laying hens, performance of productio

KETAHANAN TARIK CAMPURAN CTRB YANG MENGANDUNG 60% RAP DAN 40% RAM DENGAN SUBSTITUSI MATERIAL POZOLAN TERHADAP SEMEN

Kerusakan jalan yang terjadi pada lapis pondasi maka rehabilitasi yang harus dilakukan pada lapis pondasinya. Perbaikan yang sering dikakukan yaitu membongkar lapis pondasi yang rusak lalu menggantinya dengan material agregat batu pecah yang baru tanpa menggunakan bahan pengikat maupun menggunakan bahan pengikat berupa semen lalu dipadatkan. Dalam pelaksanaannya di lapangan, cara ini sering menghadapi tantangan yaitu secara ekonomi memerluka dana yang besar untuk pengadaan material baru, gangguan lingkungan hidup yaitu mengakibatkan daerah quarry, polusi udara dan degradasi lingkngan. Untuk mengatasi masalah tersebut maka salah satu teknologi daur ulang yaitu CTRB dapat digunakan. Campuran Cemen Treated Recycling Base (CTRB) adalah teknik daur ulang perkerasan jalan untuk lapis pondasi yang memanfaatkan RAP (Reclaimed Asphalt Pavement) yaitu material agregat yang mengandung aspal dan RAM (Reclaimed Aggregate Mineral) yaitu material agregat yang tidak mengandung aspal yang berasal dari garukan perkerasan yang telah rusak, dicampur kembali lalu distabilisasikan dengan semen. Semen sebagai bahan stabilisa pada campuran CTRB memerluka biaya yang besar. Oleh sebab itu akan disubstitusikan pozolan alam (tras) terhadap semen. Dalam penelitian ini dilakukan pengujian ITS (Indirect Tensile Strength). Dalam penelitian ini akukan dilpengujian ITS (Indirect Tensile Strength). Variasi semen yang dibuat yaitu 2%, 4%, 6%  terhadap RAP dan RAM dan variasi tras  0%, 15%, 30% terhadap semen. Variasi campuran semen dan tras yaitu 2% PC, 4% PC, 6% PC, 2% PC : 15% Tras, 4% PC : 15% Tras, 6% PC : 15% Tras, 2% PC : 30% Tras, 4% PC : 30% Tras, 6% PC : 30% Tras. Komposisi optimum campuran yang melampaui nilai ITS yaitu campuran CTRB 6% PC : 15 % Tras dan 6% PC : 30% Tras Kata Kunci: CTRB, RAP, RAM, Tras, ITS, Pozzola