[en] The strongly correlated electronic structures of cuprate high-Tc superconductors are between that of the antiferromagnetic insulating parent and highly doped paramagnetic metals. And high Tc is attainable only for a narrow range of oxidation states. This may be an indication that the electronic states of these superconductors are in the vicinity of the threshold for the creation of antiferromagnetic magnetic moments. Since the superexchange integrals are functions of the Cu-Cu separations, lattice vibrations of the Cu atoms possibly induce local antiferromagnetic magnetic moments and magnons. A modified magnon (spin wave) formalism, based on small disturbances of antiferromagnetic magnetic moments in a non-magnetic system, has been done for these superconductors. The bare magnon spectrum is found to disperse linearly for small wave vectors like the conventional antiferromagnetic magnons. Phonon-magnon interactions are found to reduce short-wave-length magnon excitation energies so that these magnons may exist even at low temperatures. (orig.)

[en] The Random Telegraph Signals (RTS's) in small MOSFET's before and after x-ray irradiation and after annealing have been studied. It is believed that the RTS's arise from the trapping/detrapping of individual defect(s) near the SiO₂/Si interface, and they are expected to be altered by ionizing radiation and annealing processes. This paper reports that the key results from this study are: RTS's existed prior to x-ray irradiation in both weak inversion and strong inversion due to process-induced defects, x-ray irradiation causes the disappearance of the original RTS and the appearance of new RTS with different emission time constants, x-ray irradiation also causes high frequency current fluctuations with much more irregular amplitude distribution than the slower RTS's, annealing at 200-300 degrees C in nitrogen removes most of the high frequency component and reveals more clearly some of the radiation-induced RTS's, and annealing at 400 degrees C essentially removes all of the radiation-induced RTS's, but causes the reappearance of one set of the original RTS traces in strong inversion. Several possibilities are discussed to account for the observations

[en] To enlarge the interaction structure to a feasible dimension and to decrease the required magnetic field to an available strength, the gyrotron devices at THz frequencies must be designed with a high-order-mode interaction, which is weaker in a beam–wave interaction and more susceptible to mode competition. Using the same interaction structure (a circular waveguide) as in the gyrotron traveling-wave amplifier (gyro-TWT), but replacing the axial magnetic field of the gyro-TWT with a tapered helical magnetic field, we found that the gyrating electrons are able to perform strong interaction with the TE11 mode in the THz region. Through an example case, we explored the behavior of the particles and wave fields as in a beam–wave interaction under a modified scheme of the gyro-TWT with a numerical simulation code. The equations required for the simulation are presented. The simulation result of the example case indicates that, through the TE11 beam–wave interaction under the presented scheme, more than one quarter of the beam energy can be converted to the wave at 612.7 GHz and to heat, dissipated on the waveguide wall, of radius 2.5 cm

[en] Full text: The p53 protein has been implicated in multiple cellular responses related to DNA damage, including apoptosis, cell cycle control, as well as DNA replication, transcription, and repair. Alterations in any of these processes could be related to increased genomic instability. Our previous study indicated that the lack of wild-type p53 does not lead to increased mutability. To investigate further how p53 is involved in regulating mutational processes, we used 8K cDNA microarrays to compare the patterns of gene expression among three closely related human cell lines with different p53 status including TK6 (wild-type p53), NH32 (p53-null), and WTK1 (mutant p53). Total RNA samples were collected at different time points (1, 3, 6, 9, and 24h) after 10Gy gamma-radiation. After template-based clustering analysis of the gene expression over the time course, our preliminary results showed that 464 genes are either up- or down-regulated by 2 fold following 10Gy radiation treatment. In addition, cluster analyses of gene expression profiles among these three cell lines revealed distinct patterns. In TK6, 175 genes were being up-regulated, while 36 genes showed down-regulation. In contrast, WTK1 showed 75 genes being up-regulated and 12 genes being down-regulated. In NH32, only 54 genes showed up-regulation. Furthermore, we found several genes associated with DNA repair such as DDB2, p53R2, XPC, PCNA, BTG2 and MSH2 were highly induced in TK6 compared to WTK1 and NH32. These TK6 up-regulated genes were confirmed by using real-time RT-PCR and are being further investigated at the protein level by Western blots

[en] To identify the driving force for the massive spalling phenomenon, carefully designed experiments were carried out. Cu-doped Sn-rich solder was reacted with Ni to form first the Sn-0.6Cu/(Cu,Ni)₆Sn₅/Ni structure. The original Sn-0.6Cu solder was then removed and replaced with Sn-0.3Cu or with fresh Sn-0.6Cu. Swapping the solder to Sn-0.3Cu caused massive spalling of (Cu,Ni)₆Sn₅. The results of this study unequivocally prove that the massive spalling reported in the literature is caused by a driving force that is purely thermodynamic in nature.

[en] The authors have used the pseudofunction (PSF) method to compute self-consistent spin-polarized energy bands for La₂CuO₄ and CuO. The ground state is found to be semiconducting and antiferromagnetic (AF) for both La₂CuO₄ and CuO. For La₂CuO₄ the Cu moment is 0.35 gm _B. For CuO, the moment is 0.68 gm _B on the Cu site and 0.19 gm _B on the O site. The moments are in agreement with neutron diffraction data

[en] Precise assessment of the extent of nasopharyngeal carcinoma (NPC) represents the basic step towards optimal treatment. We compared the capacity of CT and MRI in assessing the extent of NPC in 67 patients. MRI was superior to CT in demonstrating lesions in the retropharyngeal node, skull base, intracranial area, carotid space, longus colli muscle and levator palatini muscle. Of 25 cases in which retropharyngeal adenopathy was recognised only on MRI, seven had been reported as showing oropharyngeal involvement and 18 as primary extension to the carotid space on CT. MRI showed skull-base involvement in 40 patients compared with 27 on CT and intracranial involvement in 38 patients versus 24 on CT. There was not a single case in which skull base invasion was seen on CT but not on MRI. MRI enabled improved recognition of tumour infiltration of longus colli muscles (34 cases compared with 15 on CT). It allowed us to clarify 12 questionable sinonasal opacities on CT. Overall, T-staging was changed in 18 of 67 patients (26.9%), including upstaging in 15 cases and downstaging in 3 cases, after comparing CT with MRI. The nodel status was changed from negative on CT to positive on MRI in 4 of 67 patients (6%). We believe that MRI allows more accurate evaluation of the extent of NPC than CT and should be the primary mode of investigation. (orig.). With 6 figs., 1 tab

[en] An industrially manufactured CESR-type SRF module has been routinely operated at the Taiwan Light Source (TLS) at the National Synchrotron Radiation Research Center (NSRRC) since the beginning of March 2005. The original goals of doubling the electron beam current to increase the synchrotron light intensity and of eliminating the instability caused by the interaction of the electron beams with the cavity's higher-order modes have been successfully demonstrated. The greatest challenge to the operational reliability, the short mean time between failures, has been successfully overcome. This work reports the operational experience and status of the SRF module at TLS, toward a maximum beam current of 400 mA in decay mode, of 300 mA in top-up mode and of 200 mA in routine operation, over last six months

[en] In this work, a highly selective and self-activated (Pd-free) Co-based deposition process for capping of Cu-lines is presented. TEM images of the cross-section of capped Cu-lines show no extraneous deposition, which translates to selectivity and direct deposition of Co-based alloy on the Cu surface without Pd-activation as a pretreatment step in conventional electroless deposition. Furthermore, an 8.6% increase in the sheet resistance(Rs) via Pd-activation process which is higher than that of the Co-based self-activated process indicates that Pd may diffuse into Cu line and induce Rs increase. Results from grazing incidence X-ray diffraction (GIXRD) analysis on as-deposited Co-based films reveal that it has a nano-crystalline structure. Such structure changes very little after annealing over 400 deg. C for 30 min. AES depth profiles also reveal a uniform distribution of the elemental components and extremely low B content. Additionally, Cu was not detected on Co cap film, indicating such films could serve as diffusion barrier layers to inhibit Cu diffusion

[en] Highlights: •Decrease in the occupancy of Mn 3d orbitals with doping. •Greater splitting of the e_g orbitals due to the increased Jahn–Teller distortion with doping. •Decrease in O 2p–Mn 3d charge transfer character with doping. •Increase in charge transfer energy and band gap with doping. •Calculations hint a subtle change from a charge transfer to Mott–Hubbard type insulator with doping. -- Abstract: The electronic structures of Nd_1−xY_xMnO₃ (x = 0–0.5) were studied using X-ray absorption near-edge structure (XANES) at the Mn L_3,2- and O K-edge along with valence-band photoemission spectroscopy (VB-PES). The systematic increase in white-line intensity of the Mn L_3,2-edge with doping, suggests a decrease in the occupancy of Mn 3d orbitals. The O K-edge XANES shows a depletion of unoccupied states above the Fermi energy. The changes in the O K-edge spectra due to doping reflects an increase in the Jahn–Teller distortion. The VB-PES shows broadening of the features associated with Mn 3d and O 2p hybridized states and the shift of these features to a slightly higher binding energy in agreement with our GGA + U calculations. The system shows a net shift of the occupied and unoccupied states away from the Fermi energy with doping. The shift in theoretical site-projected density of states of x = 0.5 composition with respect to x = 0 suggest a subtle change from a charge transfer to Mott–Hubbard type insulator