25,212 research outputs found
A time of flight method to measure the speed of sound using a stereo sound card
We present an inexpensive apparatus for measuring the speed of sound, with a
time of flight method, using a computer with a stereo sound board. Students
measure the speed of sound by timing the delay between the arrivals of a pulse
to two microphones placed at different distances from the source. It can serve
as a very effective demonstration, providing a quick measurement of the speed
of sound in air; we have used it with great success in Open Days in our
Department. It can also be used for a full fledged laboratory determination of
the speed of sound in air.Comment: Accepted for publication in The Physics Teache
Using the Sound Card as a Timer
Experiments in mechanics can often be timed by the sounds they produce. In
such cases, digital audio recordings provide a simple way of measuring time
intervals with an accuracy comparable to that of photogate timers. We
illustrate this with an experiment in the physics of sports: to measure the
speed of a hard-kicked soccer ball.Comment: 3 pages, 4 figures, Late
Laboratório de enologia.
A vitivinicultura no Submédio São Francisco.bitstream/item/132811/1/ID-42731.pd
Primary osteoblast-like cells from patients with end-stage kidney disease reflect gene expression, proliferation, and mineralization characteristics ex vivo.
Osteocytes regulate bone turnover and mineralization in chronic kidney disease. As osteocytes are derived from osteoblasts, alterations in osteoblast function may regulate osteoblast maturation, osteocytic transition, bone turnover, and skeletal mineralization. Thus, primary osteoblast-like cells were cultured from bone chips obtained from 24 pediatric ESKD patients. RNA expression in cultured cells was compared with RNA expression in cells from healthy individuals, to RNA expression in the bone core itself, and to parameters of bone histomorphometry. Proliferation and mineralization rates of patient cells were compared with rates in healthy control cells. Associations were observed between bone osteoid accumulation, as assessed by bone histomorphometry, and bone core RNA expression of osterix, matrix gla protein, parathyroid hormone receptor 1, and RANKL. Gene expression of osteoblast markers was increased in cells from ESKD patients and signaling genes including Cyp24A1, Cyp27B1, VDR, and NHERF1 correlated between cells and bone cores. Cells from patients with high turnover renal osteodystrophy proliferated more rapidly and mineralized more slowly than did cells from healthy controls. Thus, primary osteoblasts obtained from patients with ESKD retain changes in gene expression ex vivo that are also observed in bone core specimens. Evaluation of these cells in vitro may provide further insights into the abnormal bone biology that persists, despite current therapies, in patients with ESKD
Influence of the soil on sensorial characteristics of Petit Verdot tropical wines from the Northeast of Brazil.
The objective of this work was to evaluate Petit Verdot varietal wines elaborate from grapes of vines cultivated in three types of soils, sandy, gravelly and clayey, different on physical and chemical characteristics, being sandy and clayey argisoils and gravelly cambosoil, by enologists
Influence of the soil on sensorial characteristics of Petit Verdot tropical wines from the Northeast of Brazil.
The objective of this work was to evaluate Petit Verdot varietal wines elaborate from grapes of vines cultivated in three types of soils, sandy, gravelly and clayey, different on physical and chemical characteristics, being sandy and clayey argisoils and gravelly cambosoil, by enologists
Photonic superdiffusive motion in resonance line radiation trapping - partial frequency redistribution effects
The relation between the jump length probability distribution function and
the spectral line profile in resonance atomic radiation trapping is considered
for Partial Frequency Redistribution (PFR) between absorbed and reemitted
radiation. The single line Opacity Distribution Function [M.N. Berberan-Santos
et.al. J.Chem.Phys. 125, 174308 (2006)] is generalized for PFR and used to
discuss several possible redistribution mechanisms (pure Doppler broadening,
combined natural and Doppler broadening and combined Doppler, natural and
collisional broadening). It is shown that there are two coexisting scales with
a different behavior: the small scale is controlled by the intricate PFR
details while the large scale is essentially given by the atom rest frame
redistribution asymptotic. The pure Doppler and combined natural, Doppler and
collisional broadening are characterized by both small and large scale
superdiffusive Levy flight behaviors while the combined natural and Doppler
case has an anomalous small scale behavior but a diffusive large scale
asymptotic. The common practice of assuming complete redistribution in core
radiation and frequency coherence in the wings of the spectral distribution is
incompatible with the breakdown of superdiffusion in combined natural and
Doppler broadening conditions
Variabilidade genética de matrizes de pequizeiro selecionadas para estudos na Embrapa Cerrados e na UPIS- Faculdades Integradas, com base nos marcadores RAPD.
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