1,204 research outputs found
Wafer-level packaged RF-MEMS switches fabricated in a CMOS fab
Reports on wafer-level packaged RF-MEMS switches fabricated in a commercial CMOS fab. Switch fabrication is based on a metal surface micromachining process. A novel wafer-level packaging scheme is developed, whereby the switches are housed in on-chip sealed cavities using benzocyclobutene (BCB) as the bonding and sealing material. Measurements show that the influence of the wafer-level package on the RF performance can be made very small.\ud
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Commensurate and Incommensurate Vortex States in Superconductors with Periodic Pinning Arrays
As a function of applied field, we find a rich variety of ordered and
partially-ordered vortex lattice configurations in systems with square or
triangular arrays of pinning sites. We present formulas that predict the
matching fields at which commensurate vortex configurations occur and the
vortex lattice orientation with respect to the pinning lattice. Our results are
in excellent agreement with recent imaging experiments on square pinning arrays
[K. Harada et al., Science 274, 1167 (1996)].Comment: 9 pages, 3 figures. Accepted to Physical Review
Revisiting Reader Privacy in the Age of the E-Book, 45 J. Marshall L. Rev. 175 (2011)
status: publishe
London equation studies of thin-film superconductors with a triangular antidot lattice
We report on a study of vortex pinning in nanoscale antidot defect arrays in
the context of the London Theory. Using a wire network model, we discretize the
array with a fine mesh, thereby providing a detailed treatment of pinning
phenomena. The use of a fine grid has enabled us to examine both circular and
elongated defects, patterned in the form of a rhombus. The latter display
pinning characteristics superior to circular defects constructed with the
similar area. We calculate pinning potentials for defects containing zero and
single quanta, and we obtain a pinning phase diagram for the second matching
field, .Comment: 10 pages and 14 figure
Individual and Multi Vortex Pinning in Systems with Periodic Pinning Arrays
We examine multi and individual vortex pinning in thin superconductors with
periodic pinning arrays. For multi-vortex pinning we observe peaks in the
critical current of equal magnitude at every matching field, while for
individual vortex pinning we observe a sharp drop in the critical current after
the first matching field in agreement with experiments. We examine the scaling
of the critical current at commensurate and incommensurate fields for varied
pinning strength and show that the depinning force at incommensurate fields
decreases faster than at the commensurate fields.Comment: 4 figuure
Vortex phase diagram for mesoscopic superconducting disks
Solving numerically the 3D non linear Ginzburg-Landau (GL) equations, we
study equilibrium and nonequilibrium phase transitions between different
superconducting states of mesoscopic disks which are thinner than the coherence
length and the penetration depth. We have found a smooth transition from a
multi-vortex superconducting state to a giant vortex state with increasing both
the disk thickness and the magnetic field. A vortex phase diagram is obtained
which shows, as function of the magnetic field, a re-entrant behavior between
the multi-vortex and the giant vortex state.Comment: 5 figures (post script files) include
Dynamic Phases of Vortices in Superconductors with Periodic Pinning
We present results from extensive simulations of driven vortex lattices
interacting with periodic arrays of pinning sites. Changing an applied driving
force produces a rich variety of novel dynamical plastic flow phases which are
very distinct from those observed in systems with random pinning arrays.
Signatures of the transition between these different dynamical phases include
sudden jumps in the current-voltage curves as well as marked changes in the
vortex trajectories and the vortex lattice order. Several dynamical phase
diagrams are obtained as a function of commensurability, pinning strength, and
spatial order of the pinning sites.Comment: 4 pages, 3 figures. To appear in Physical Review Letters. Movies
available at http://www-personal.engin.umich.edu/~nor
Opposite macrophage polarization in different subsets of ovarian cancer: observation from a pilot study
The role of the innate immune system in ovarian cancer is gaining importance. The relevance of tumor-associated macrophages (TAM) is insufficiently understood. In this pilot project, comprising the immunofluorescent staining of 30 biopsies taken from 24 patients with ovarian cancer, we evaluated the presence of total TAM (cluster of differentiation (CD) 68 expression), M1 (major histocompatibility complex (MHC) II expression), and M2 (anti-mannose receptor C type 1 (MRC1) expression), and the blood vessel diameter. We observed a high M1/M2 ratio in low-grade ovarian cancer compared to high-grade tumors, more total TAM and M2 in metastatic biopsies, and a further increase in total TAM and M2 at interval debulking, without beneficial effects of bevacizumab. The blood vessel diameter was indicative for M2 tumor infiltration (Spearman correlation coefficient of 0.65). These data mainly reveal an immune beneficial environment in low-grade ovarian cancer in contrast to high-grade serous ovarian cancer, where immune suppression is not altered by neoadjuvant therapy
Shapiro steps in a superconducting film with an antidot lattice
Shapiro voltage steps at voltages V_n=nV_0 (n integer) have been observed in
the voltage-current characteristics of a superconducting film with a square
lattice of perforating microholes (antidots)in the presence of radiofrequent
radiation. These equidistant steps appear at the second matching field H_2 when
the flow of the interstitial vortex lattice in the periodic potential created
by the antidots and the vortices trapped by them, is in phase with the applied
rf frequency. Therefore, the observation of Shapiro steps clearly reveals the
presence of mobile intersitial vortices in superconducting films with regular
pinning arrays. The interstitial vortices, moved by the driving current,
coexist with immobile vortices strongly pinned at the antidots.Comment: 6 pages text, 3 EPS figures, RevTeX, accepted for publication in PRB
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