13,206 research outputs found
Long-range elastic guidance mechanisms for electrostatic comb-drive actuators
The range of motion and output force of the often used electrostatic comb-drive with folded flexure straight guidance, as shown in Figure 1, is limited by sideways instability due to poor sideways stiffness of the folded flexure at relatively large deflections [1]
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The late Cretaceous environment of the Arctic: A quantitative reassessment based on plant fossils
Late Cretaceous megafossil floras from the palaeo-Arctic of northeastern Russia and northern Alaska are reviewed in respect of their age, composition, structure and floral dynamics. Palaeofloral correlations and comparisons are made between the two regions. Nine angiosperm-rich, predominantly Cenomanian to Coniacian, floras from the palaeo-Arctic are re-evaluated using Climate Leaf Analysis Multivariate Program (CLAMP) calibrated using a global gridded (0.5° x 0.5°) climate data set derived from that used in climate modelling. Additional floras from lower palaeolatitudes were used to derive latitudinal temperature gradients: seven from N. America, five from around 30 °N palaeolatitude in Europe and one from Kazakhstan. The Arctic climatic determinations, similar to previous estimates, support the existence of a northern Pacific Ocean cold gyre and a warm Arctic Ocean. At palaeolatitudes greater than 80°N floras are insufficiently diverse in woody dicot taxa to use CLAMP, but using CLAMP-derived latitudinal temperature gradients Arctic Ocean coastal environments at 70 Ma and 82°N, and which supported a diverse dinosaur magafauna, are predicted to have experienced a mean annual temperature of 6.3 ± 2.2°C, a warm month mean of 14.5 ± 3.1°C and a cold month mean no colder than -2.0 ± 3.9°C. All uncertainties are 2σ. The new estimates are in good agreement with a wide range of non-palaeobotanical climate proxies and render as an outlier warmer temperature estimates for the Arctic Ocean derived from the TEX86 proxy. Modelling, however, shows that land to ocean temperature gradients could have been steep. The CLAMP estimates also suggest high values for humidity and precipitation consistent with sedimentological indicators and, coupled with warm temperatures, support the existence of a persistent polar cloud cap that helped maintain high terrestrial air temperatures throughout prolonged periods (up to 5 months) of winter darkness
Linear Superiorization for Infeasible Linear Programming
Linear superiorization (abbreviated: LinSup) considers linear programming
(LP) problems wherein the constraints as well as the objective function are
linear. It allows to steer the iterates of a feasibility-seeking iterative
process toward feasible points that have lower (not necessarily minimal) values
of the objective function than points that would have been reached by the same
feasiblity-seeking iterative process without superiorization. Using a
feasibility-seeking iterative process that converges even if the linear
feasible set is empty, LinSup generates an iterative sequence that converges to
a point that minimizes a proximity function which measures the linear
constraints violation. In addition, due to LinSup's repeated objective function
reduction steps such a point will most probably have a reduced objective
function value. We present an exploratory experimental result that illustrates
the behavior of LinSup on an infeasible LP problem.Comment: arXiv admin note: substantial text overlap with arXiv:1612.0653
Pengetahuan, Sikap Dan Perilaku Remaja Tentang Keluarga Sadar Gizi (Kadarzi): Dengan Perhatian Khusus Terhadap Pantauan Berat Badan Dan Mengonsumsi Makanan Beragam
Latar belakang: Kualitas remaja sangat mempengaruhi masa depan suatu bangsa. Pengetahuan sikap dan perilaku remaja tentang keluarga sadar gizi (KADARZI) utamanya pengetahuan tentang pentingnya memantau berat badan dan mengonsumsi beraneka ragam makanan akan mempengaruhi status gizi dan kesehatannya masa kini, maupun di kemudian hari. Tujuan penelitian: Mendapatkan gambaran PSP remaja tentang KADARZI, utamanya tentang pentingnya pemantauan berat badan dan mengonsumsi aneka ragam makanan. Metode: Desain penelitian adalah kros-seksional. Penelitian dilakukan di 226 posyandu yang tersebar di 6 provinsi yaitu provinsi Sumatera Barat, Jawa Barat, Kalimantan Timur, Nusa Tenggara Barat, Sulawesi Selatan dan Nusa Tenggara Timur. Jumlah seluruh sampel adalah 970 remaja dari 4289 rumah tangga. Pemilihan sampel kabupaten sampai posyandu dilakukan secara purposif dan sampel rumah tangga dilakukan secara acak. Remaja dari rumah tangga terpilih dicakup dalam studi ini. Data yang dikumpulkan meliputi pengetahuan, sikap dan perilaku berbagai aspek gizi remaja. Pengolahan data dilakukan secara deskriptif untuk memperoleh gambaran kesadaran gizi remaja menurut indikator kadarzi. Hasil: Secara umum pengetahuan remaja pada beberapa aspek gizi cukup baik yakni: 90,6% mengetahui manfaat sarapan pagi, 65% tanda–tanda gizi buruk. Tetapi pengetahuan tentang aspek gizi lain masih rendah, <20% remaja mengetahui tentang ASI eksklusif dan pentingnya makanan beraneka ragam. Sementara sikap dan perilaku yang berkait dengan sarapan pagi, hampir 100% bersikap positip dan 60% bersikap positip pada memantau berat badan. Akan tetapi perilaku berkait dengan penimbangan dan mengonsumsi aneka ragam makanan relatif masih rendah yakni 26,5% dan 18,8%. Kesimpulan: Sekitar seperempat (26%) responden yang memantau atau menimbang berat badannya secara teratur, dan kurang dari 20% responden remaja yang mengonsumsi makanan beraneka ragam. Saran: Perlu edukasi gizi yang intensif kepada remaja dan pemangku kepentingan (stakeholder)
Pharmacokinetic analysis after implantation of everolimus-eluting self-expanding stents in the peripheral vasculature
Background: A novel self-expanding drug-eluting stent was designed to release everolimus 225 mu g/cm(2) to prevent restenosis following peripheral arterial intervention. The purpose of this study was to measure the pharmacokinetic profile of everolimus following stent implantation.
Methods: One hundred four patients with symptomatic peripheral arterial disease underwent implantation of everolimus-eluting stents in the femoropopliteal arteries. In a prespecified subset of 26 patients, blood samples for assay of everolimus content were collected prior to stent implantation, at 1, 4, and 8 hours postprocedure, prior to discharge, and at 1 month postproccdure.
Results: A total of 39 stents, ranging from 28 mm to 100 mm in length, were implanted in 26 patients, resulting in a total delivered everolimus dose range of 3.0 to 7.6 mg. Following the procedure, the maximum observed everolimus blood concentrations (C-max) varied from 1.83 +/- 0.05 ng/mL after implantation of a single 80-mm stent to 4.66 +/- 1.78 ng/mL after implantation of two 100-mm stents. The mean time to peak concentration (T-max) varied from 6.8 hours to 35 hours. The pharmacokinetics of everolimus were dose-proportional in that dose-normalized C-max and area under the curve values were constant over the studied dose range.
Conclusions: After implantation of everolimus-eluting self-expanding stents in the femoropopliteal arteries, systemic blood concentrations of everolimus are predictable and considerably lower than blood concentrations observed following safe oral administration of everolimus
Bardeen-Petterson effect and the disk structure of the Seyfert galaxy NGC 1068
VLBA high spatial resolution observations of the disk structure of the active
galactic nucleus NGC 1068 has recently revealed that the kinematics and
geometry of this AGN is well characterized by an outer disk of H2O maser
emission having a compact milliarcsecond (parsec) scale structure, which is
encircling a thin rotating inner disk surrounding a ~10^7 M_\sun compact
mass, likely a black hole. A curious feature in this source is the occurrence
of a misalignment between the inner and outer parts of the disk, with the
galaxy's radio jet being orthogonal to the inner disk. We interpret this
peculiar configuration as due to the Bardeen-Petterson effect, a general
relativistic effect that warps an initially inclined (to the black hole
equator) viscous disk, and drives the angular momentum vector of its inner part
into alignment with the rotating black hole spin. We estimate the time-scale
for both angular momenta to get aligned as a function the spin parameter of the
Kerr black hole. We also reproduce the shape of the parsec and kiloparsec scale
jets, assuming a model in which the jet is precessing with a period and
aperture angle that decrease exponentially with time, as expected from the
Bardeen-Petterson effect.Comment: 12 pages, 3 figures, accepted for publication in The Astrophysical
Journa
Ballistic deposition patterns beneath a growing KPZ interface
We consider a (1+1)-dimensional ballistic deposition process with
next-nearest neighbor interaction, which belongs to the KPZ universality class,
and introduce for this discrete model a variational formulation similar to that
for the randomly forced continuous Burgers equation. This allows to identify
the characteristic structures in the bulk of a growing aggregate ("clusters"
and "crevices") with minimizers and shocks in the Burgers turbulence, and to
introduce a new kind of equipped Airy process for ballistic growth. We dub it
the "hairy Airy process" and investigate its statistics numerically. We also
identify scaling laws that characterize the ballistic deposition patterns in
the bulk: the law of "thinning" of the forest of clusters with increasing
height, the law of transversal fluctuations of cluster boundaries, and the size
distribution of clusters. The corresponding critical exponents are determined
exactly based on the analogy with the Burgers turbulence and simple scaling
considerations.Comment: 10 pages, 5 figures. Minor edits: typo corrected, added explanation
of two acronyms. The text is essentially equivalent to version
Reproductive success through high pollinator visitation rates despite self incompatibility in an endangered wallflower
PREMISE OF THE STUDY: Self incompatibility (SI) in rare plants presents a unique challenge—SI protects plants from inbreeding depression, but requires a sufficient number of mates and xenogamous pollination. Does SI persist in an endangered polyploid? Is pollinator visitation sufficient to ensure reproductive success? Is there evidence of inbreeding/outbreeding depression? We characterized the mating system, primary pollinators, pollen limitation, and inbreeding/outbreeding depression in Erysimum teretifolium to guide conservation efforts. METHODS: We compared seed production following self pollination and within- and between-population crosses. Pollen tubes were visualized after self pollinations and between-population pollinations. Pollen limitation was tested in the field. Pollinator observations were quantified using digital video. Inbreeding/outbreeding depression was assessed in progeny from self and outcross pollinations at early and later developmental stages. KEY RESULTS: Self-pollination reduced seed set by 6.5× and quadrupled reproductive failure compared with outcross pollination. Pollen tubes of some self pollinations were arrested at the stigmatic surface. Seed-set data indicated strong SI, and fruit-set data suggested partial SI. Pollinator diversity and visitation rates were high, and there was no evidence of pollen limitation. Inbreeding depression (δ) was weak for early developmental stages and strong for later developmental stages, with no evidence of outbreeding depression. CONCLUSIONS: The rare hexaploid E. teretifolium is largely self incompatible and suffers from late-acting inbreeding depression. Reproductive success in natural populations was accomplished through high pollinator visitation rates consistent with a lack of pollen limitation. Future reproductive health for this species will require large population sizes with sufficient mates and a robust pollinator community
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