Anomalous double peak structure in Nb/Ni superconductor/ferromagnet tunneling DOS

We have experimentally investigated the density of states (DOS) in Nb/Ni (S/F) bilayers as a function of Ni thickness, $d_F$. Our thinnest samples show the usual DOS peak at $\pm\Delta_0$, whereas intermediate-thickness samples have an anomalous ``double-peak'' structure. For thicker samples ($d_F \geq 3.5$ nm), we see an ``inverted'' DOS which has previously only been reported in superconductor/weak-ferromagnet structures. We analyze the data using the self-consistent non-linear Usadel equation and find that we are able to quantitatively fit the features at $\pm\Delta_0$ if we include a large amount of spin-orbit scattering in the model. Interestingly, we are unable to reproduce the sub-gap structure through the addition of any parameter(s). Therefore, the observed anomalous sub-gap structure represents new physics beyond that contained in the present Usadel theory.Comment: 4 pages, 3 figure

Aplikasi Reservasi kamar pada Penginapan Timur Palembang

Tujuan penulisan tugas akhir ini adalah untuk merancangdan membangun aplikasi pengelolaan data reservasi kamar berbasis web pada Penginapan Timur Palembang. Aplikasi ini berfungsi untuk memenuhi kebutuhan sistem yang ada pada pemesanan kamar (reservasi). Aplikasi ini berguna untuk mempermudah dalam pencarian dan proses pencatatan transaksi dan lebih menghemat waktu. Metodologi yang digunakan dalam pengembangan aplikasi ini adalah metodologi iterasi dengan langkah-langkah: perencanaan, analisis, desain,dan penerapan. Dari hasil pembahasan tersebut maka penulis menyimpulkan bahwa dengan adanya aplikasi pengelolaan data reservasi ini, kinerja administrasi dapat meningkatkan dan meminimalkan kesalahan dalam mencatat data pelanggan, data pemesanan, data pembayaran, dan pembuatan laporan

Studies of YBCO Strip Lines under Voltage Pulses: Optimisation of the Design of Fault Current Limiters

We present experimental results on the behaviour of a superconducting YBCO/Au meander of length L submitted to short circuit tests with constant voltage pulses. The meander, at the beginning of the short-circuit, is divided in two regions; one, with a length L1 proportional to the applied voltage, which first switches into a highly dissipative state (HDS) while the rest remains superconducting. Then the rest of the meander will progressively switch into the normal state due to the propagation of this HDS (few m/s) from both ends. The part L1 has to initially support a power density proportional to r.Jp^2 (r is the resistivity of the bilayer and Jp the peak current density). To avoid local excessive dissipation of power and over heating on one part of the wafer in the initial period, we have developed a novel design in order to distribute the dissipating section of the meander into many separated small dissipative zones. Furthermore the apparent propagation velocity of these dissipative zones is increased by the number of propagation fronts. We will show results obtained on 3kW (300V, 10A) FCL on a 2" wafer which confirm the benefits of this new design.Comment: 4 pages, 6 figures; presented at the Applied Superconductivity Conference in Houston, TX (August 2002); to be published in IEEE Trans. On Appl. Supercon

Random insertion of GFP into the cAMP-dependent protein kinase regulatory subunit from Dictyostelium discoideum

The green fluorescent protein (GFP) is currently being used for diverse cellular biology approaches, mainly as a protein tag or to monitor gene expression. Recently it has been shown that GFP can also be used to monitor the activation of second messenger pathways by the use of fluorescence resonance energy transfer (FRET) between two different GFP mutants fused to a Ca2+ sensor. We show here that GFP fusions can also be used to obtain information on regions essential for protein function. As FRET requires the two GFPs to be very close, N- or C-terminal fusion proteins will not generally produce FRET between two interacting proteins. In order to increase the probability of FRET, we decided to study the effect of random insertion of two GFP mutants into a protein of interest. We describe here a methodology for random insertion of GFP into the cAMP-dependent protein kinase regulatory subunit using a bacterial expression vector. The selection and analysis of 120 green fluorescent colonies revealed that the insertions were distributed throughout the R coding region. 14 R/GFP fusion proteins were partially purified and characterized for cAMP binding, fluorescence and ability to inhibit PKA catalytic activity. This study reveals that GFP insertion only moderately disturbed the overall folding of the protein or the proper folding of another domain of the protein, as tested by cAMP binding capacity. Furthermore, three R subunits out of 14, which harbour a GFP inserted in the cAMP binding site B, inhibit PKA catalytic subunit in a cAMP-dependent manner. Random insertion of GFP within the R subunit sets the path to develop two-component FRET with the C subuni

RhoB regulates cell migration through altered focal adhesion dynamics

The Rho GTPase RhoB has been shown to affect cell migration, but how it does this is not clear. Here we show that cells depleted of RhoB by RNAi are rounded and have defects in Rac-mediated spreading and lamellipodium extension, although they have active membrane ruffling around the periphery. Depletion of the exchange factor GEF-H1 induces a similar phenotype. RhoB-depleted cells migrate faster, but less persistently in a chemotactic gradient, and frequently round up during migration. RhoB-depleted cells have similar numbers of focal adhesions to control cells during spreading and migration, but show more diffuse and patchy contact with the substratum. They have lower levels of surface β1 integrin, and β1 integrin activity is reduced in actin-rich protrusions. We propose that RhoB contributes to directional cell migration by regulating β1 integrin surface levels and activity, thereby stabilizing lamellipodial protrusions