12,542 research outputs found
Float-polishing process and analysis of float-polished quartz
A fluid-mechanical model is developed for the float-polishing process. In this model laminar flow between the sample and the lap results in pressure gradients at the grooves that support the sample on a fluid layer. The laminar fluid motion also produces supersmooth, damage-free surfaces. Quartz substrates for applications in high-stress environments were float polished, and their surfaces were analyzed by optical scatterometry, photoacoustic spectroscopy, and atomic force microscopy. The removal of 100 µm of material by a lapping-polishing process, with final float polishing, left low levels of subsurface damage, with a surface roughness of approximately 0.2-nm rms
On The Determination of MDI High-Degree Mode Frequencies
The characteristic of the solar acoustic spectrum is such that mode lifetimes
get shorter and spatial leaks get closer in frequency as the degree of a mode
increases for a given order. A direct consequence of this property is that
individual p-modes are only resolved at low and intermediate degrees, and that
at high degrees, individual modes blend into ridges. Once modes have blended
into ridges, the power distribution of the ridge defines the ridge central
frequency and it will mask the true underlying mode frequency. An accurate
model of the amplitude of the peaks that contribute to the ridge power
distribution is needed to recover the underlying mode frequency from fitting
the ridge.
We present the results of fitting high degree power ridges (up to l = 900)
computed from several two to three-month-long time-series of full-disk
observations taken with the Michelson Doppler Imager (MDI) on-board the Solar
and Heliospheric Observatory between 1996 and 1999.
We also present a detailed discussion of the modeling of the ridge power
distribution, and the contribution of the various observational and
instrumental effects on the spatial leakage, in the context of the MDI
instrument. We have constructed a physically motivated model (rather than some
ad hoc correction scheme) resulting in a methodology that can produce an
unbiased determination of high-degree modes, once the instrumental
characteristics are well understood.
Finally, we present changes in high degree mode parameters with epoch and
thus solar activity level and discuss their significance.Comment: 59 pages, 38 figures -- High-resolution version at
http://www-sgk.harvard.edu:1080/~sylvain/preprints/ -- Manuscript submitted
to Ap
Image Subtraction Reduction of Open Clusters M35 & NGC 2158 In The K2 Campaign-0 Super-Stamp
Observations were made of the open clusters M35 and NGC 2158 during the
initial K2 campaign (C0). Reducing these data to high-precision photometric
time-series is challenging due to the wide point spread function (PSF) and the
blending of stellar light in such dense regions. We developed an
image-subtraction-based K2 reduction pipeline that is applicable to both
crowded and sparse stellar fields. We applied our pipeline to the data-rich C0
K2 super-stamp, containing the two open clusters, as well as to the neighboring
postage stamps. In this paper, we present our image subtraction reduction
pipeline and demonstrate that this technique achieves ultra-high photometric
precision for sources in the C0 super-stamp. We extract the raw light curves of
3960 stars taken from the UCAC4 and EPIC catalogs and de-trend them for
systematic effects. We compare our photometric results with the prior
reductions published in the literature. For detrended, TFA-corrected sources in
the 12--12.25 magnitude range, we achieve a best 6.5 hour window
running rms of 35 ppm falling to 100 ppm for fainter stars in the 14--14.25 magnitude range. For stars with , our detrended and
6.5 hour binned light curves achieve the highest photometric precision.
Moreover, all our TFA-corrected sources have higher precision on all time
scales investigated. This work represents the first published image subtraction
analysis of a K2 super-stamp. This method will be particularly useful for
analyzing the Galactic bulge observations carried out during K2 campaign 9. The
raw light curves and the final results of our detrending processes are publicly
available at \url{http://k2.hatsurveys.org/archive/}.Comment: Accepted for publication in PASP. 14 pages, 5 figures, 2 tables.
Light curves available from http://k2.hatsurveys.org/archive
Rotation intrinsic spin coupling--the parallelism description
For the Dirac particle in the rotational system, the rotation induced inertia
effect is analogously treated as the modification of the "spin connection" on
the Dirac equation in the flat spacetime, which is determined by the equivalent
tetrad. From the point of view of parallelism description of spacetime, the
obtained torsion axial-vector is just the rotational angular velocity, which is
included in the "spin connection". Furthermore the axial-vector spin coupling
induced spin precession is just the rotation-spin(1/2) interaction predicted by
Mashhoon. Our derivation treatment is straightforward and simplified in the
geometrical meaning and physical conception, however the obtained conclusions
are consistent with that of the other previous work.Comment: 10 pages, no figur
Exact Nonequilibrium Work Generating Function for a Small Classical System
We obtain the exact nonequilibrium work generating function (NEWGF), for a
small system consisting of a massive Brownian particle connected to internal
and external springs. The external work is provided to the system for a finite
time interval. The Jarzynski equality (JE), obtained in this case directly from
the NEWGF, is shown to be valid for the present model, in an exact way
regardless of the rate of external work
Short-term exposure to elevated CO2 stimulates growth and metabolic responses that alleviate early-stage iron deficiency symptoms in soybean
Elevated CO2 (eCO(2)) increase plant biomass and might lead to nutritional losses. The results showed that eCO(2) under Fe-deficiency stimulates root dry weight from 0.37-0.80 g plant(-1) and shoot dry weight from 0.82-2.10 g plant(-1), without compromising root/shoot ratio. Besides, eCO(2) improved the chlorophyl content of Fe-deficient plants. However, downregulation of photosynthesis, reduction in stomatal conductance and transpiration rate, and an increase in water-use efficiency was observed due to eCO(2). Moreover, under Fe-deficiency, eCO(2) decreased K and Mg in roots, and Mg in leaves, whereas increased P and Zn in roots and leaves. In Fe-sufficient plants, eCO(2) increased K, P, Mn, Zn and Fe in leaves and did not change the concentration in roots. The Fe-deficiency-induced responses in roots, including the increase in FCR activity, and the expression of Fe-uptake genes were stimulated by eCO(2), but were not sufficient to increase Fe concentration in Fe-deficient plants.info:eu-repo/semantics/publishedVersio
Detrended Fluctuation Analysis of Systolic Blood Pressure Control Loop
We use detrended fluctuation analysis (DFA) to study the dynamics of blood
pressure oscillations and its feedback control in rats by analyzing systolic
pressure time series before and after a surgical procedure that interrupts its
control loop. We found, for each situation, a crossover between two scaling
regions characterized by exponents that reflect the nature of the feedback
control and its range of operation. In addition, we found evidences of
adaptation in the dynamics of blood pressure regulation a few days after
surgical disruption of its main feedback circuit. Based on the paradigm of
antagonistic, bipartite (vagal and sympathetic) action of the central nerve
system, we propose a simple model for pressure homeostasis as the balance
between two nonlinear opposing forces, successfully reproducing the crossover
observed in the DFA of actual pressure signals
O estresse no manejo pré-abate e na qualidade da carne suína.
O estresse no manejo pré-abate e na qualidade da carne suína; Caracterização do estresse; Avaliação da resposta fisiológica dio estresse; Formas de avaliações; Determinação do cortisol; Determinação de lactato; Mecanismos através dos quais podem afetar a qualidade da carne; Influência da genética na qualidade da carne; Gene rendimento napole (RN); gene Halotano; Situações de estresse no manejo pré-abate.bitstream/item/58222/1/publicacao-i7n63h7v1.pd
Effect of the interaction between elevated carbon dioxide and iron limitation on proteomic profiling of soybean
Elevated atmospheric CO2 (eCO2) and iron (Fe) availability are important factors affecting plant growth that may impact the proteomic profile of crop plants. In this study, soybean plants treated under Fe-limited (0.5 mM) and Fe-sufficient (20 mM) conditions were grown at ambient (400 μmol mol−1) and eCO2 (800 μmol mol−1) in hydroponic solutions. Elevated CO2 increased biomass from 2.14 to 3.14 g plant−1 and from 1.18 to 2.91 g plant−1 under Fe-sufficient and Fe-limited conditions, respectively, but did not affect leaf photosynthesis. Sugar concentration increased from 10.92 to 26.17 μmol g FW−1 in roots of Fe-sufficient plants and from 8.75 to 19.89 μmol g FW−1 of Fe-limited plants after exposure to eCO2. In leaves, sugar concentration increased from 33.62 to 52.22 μmol g FW−1 and from 34.80 to 46.70 μmol g FW−1 in Fe-sufficient and Fe-limited conditions, respectively, under eCO2. However, Fe-limitation decreases photosynthesis and biomass. Pathway enrichment analysis showed that cell wall organization, glutathione metabolism, photosynthesis, stress-related proteins, and biosynthesis of secondary compounds changed in root tissues to cope with Fe-stress. Moreover, under eCO2, at sufficient or limited Fe supply, it was shown an increase in the abundance of proteins involved in glycolysis, starch and sucrose metabolism, biosynthesis of plant hormones gibberellins, and decreased levels of protein biosynthesis. Our results revealed that proteins and metabolic pathways related to Fe-limitation changed the effects of eCO2 and negatively impacted soybean production.info:eu-repo/semantics/publishedVersio
Development and exploratory cluster-randomised opportunistic trial of a theory-based intervention to enhance physical activity among adolescents
Peer reviewedPostprin
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