scholarly journals Effects of Multiconstituent Tides on a Subterranean Estuary With Fixed-Head Inland Boundary

2021 ◽  
Vol 8 ◽  
Author(s):  
Xiayang Yu ◽  
Pei Xin ◽  
Chengji Shen ◽  
Ling Li
Keyword(s):  
Coastal Aquifers ◽  
Functional Data ◽  
High Frequency ◽  
Submarine Groundwater Discharge ◽  
Low Frequency ◽  
Freshwater Input ◽  
Frequency Spectra ◽  
Subterranean Estuary ◽  
Unconfined Aquifers ◽  
Tidal Constituents

While tides of multiple constituents are common in coastal areas, their effects on submarine groundwater discharge (SGD) and salinity distributions in unconfined coastal aquifers are rarely examined, with the exception of a recent study that explored such effects on unconfined aquifers with fixed inland freshwater input. For a large proportion of the global coastline, the inland areas of coastal aquifers are topography-limited and controlled by constant heads. Based on numerical simulations, this article examines the variation of SGD and salinity distributions in coastal unconfined aquifers with fixed-head inland boundaries at different distances from the shoreline (i.e., 50, 100, 150, and 200 m). The results showed that the fluctuation intensity of freshwater input was enhanced as the inland aquifer extent decreased, e.g., the range of tide-induced fluctuations in freshwater input increased by around 5 times as the inland aquifer extent decreased from 200 to 50 m. The frequency spectra of the fluctuations of SGD and salinity distributions showed that the coastal aquifer of a shorter inland aquifer extent smoothed out fewer high-frequency tidal constituents but enhanced interaction among different tidal constituents. The interaction among tidal constituents generated new low-frequency signals in the freshwater input and salinity distributions. Regressions based on functional data analysis demonstrated that the inland freshwater input and salinity distributions at any given moment were related to the antecedent (previous) tidal conditions weighted using the probability density function of the Gamma distribution. The influence of the antecedent tidal conditions depended on the inland aquifer extent.

Concentration Fluctuation Spectra in Turbulent Slurry Pipeline Flow

1989 ◽  
Vol 111 (3) ◽  
pp. 317-323 ◽  
Author(s):  
R. J. Sumner ◽  
C. A. Shook ◽  
M. C. Roco
Keyword(s):  
Cross Section ◽  
Electrical Resistance ◽  
High Frequency ◽  
Particle Diameter ◽  
Low Frequency ◽  
Frequency Spectra ◽  
Concentration Time ◽  
Solids Concentration ◽  
Slurry Flows ◽  
Effective Domain

Using probes responding to changes of slurry electrical resistance with concentration, time spectra of longitudinal concentration fluctuations in turbulent slurry flows have been measured. The sensors, with an effective domain approximately 1 mm in diameter, showed the spectra to be relatively insensitive to location within the pipe cross section. High frequency spectra were found to be relatively insensitive to slurry concentration and particle diameter. Low frequency spectra showed fluctuation amplitudes which increased with solids concentration.

Two-week normobaric intermittent hypoxia exposures enhance oxyhemoglobin equilibrium and cardiac responses during hypoxemia

2014 ◽  
Vol 307 (6) ◽  
pp. R721-R730 ◽  
Author(s):  
Peizhen Zhang ◽  
H. Fred Downey ◽  
Shande Chen ◽  
Xiangrong Shi
Keyword(s):  
High Frequency ◽  
Respiratory Function ◽  
Intermittent Hypoxia ◽  
Low Frequency ◽  
Frequency Spectra ◽  
Rightward Shift ◽  
Cardiac Responses ◽  
Arterial Blood ◽  
Equilibrium Response ◽  
End Tidal

Intermittent hypoxia (IH) is extensively applied to challenge cardiovascular and respiratory function, and to induce physiological acclimatization. The purpose of this study was to test the hypothesis that oxyhemoglobin equilibrium and tachycardiac responses during hypoxemia were enhanced after 14-day IH exposures. Normobaric-poikilocapnic hypoxia was induced with inhalation of 10% O2 for 5–6 min interspersed with 4 min recovery on eight nonsmokers. Heart rate (HR), arterial O2 saturation (SaO2), and end-tidal O2 (PetO2) were continuously monitored during cyclic normoxia and hypoxia. These variables were compared during the first and fifth hypoxic bouts between day 1 and day 14. There was a rightward shift in the oxyhemoglobin equilibrium response following 14-day IH exposures, as indicated by the greater PetO2 (an index of arterial Po2) at 50% of SaO2 on day 14 compared with day 1 [33.9 ± 1.5 vs. 28.2 ± 1.3 mmHg ( P = 0.005) during the first hypoxic bout and 39.4 ± 2.4 vs. 31.4 ± 1.5 mmHg ( P = 0.006) during the fifth hypoxic bout] and by the augmented gains of ΔSaO2/ΔPetO2 (i.e., deoxygenation) during PetO2 from 65 to 40 mmHg in the first (1.12 ± 0.08 vs. 0.80 ± 0.02%/mmHg, P = 0.001) and the fifth (1.76 ± 0.31 vs. 1.05 ± 0.06%/mmHg, P = 0.024) hypoxic bouts. Repetitive IH exposures attenuated ( P = 0.049) the tachycardiac response to hypoxia while significantly enhancing normoxic R-R interval variability in low-frequency and high-frequency spectra without changes in arterial blood pressure at rest or during hypoxia. We conclude that 14-day IH exposures enhance arterial O2 delivery and improve vagal control of HR during hypoxic hypoxemia.

scholarly journals How well are FREQUENCY SENSITIVITIES OF grasshopper ears tuned to species-specific song spectra?

1996 ◽  
Vol 199 (7) ◽  
pp. 1631-1642
Author(s):  
J Meyer ◽  
N Elsner
Keyword(s):  
High Frequency ◽  
Broad Band ◽  
Low Frequency ◽  
Attachment Site ◽  
The Body ◽  
Frequency Range ◽  
Frequency Spectra ◽  
Interspecific Differences ◽  
Tympanal Membrane ◽  
Species Specific

Grasshoppers of 20 acridid species were examined using spectral analysis, laser vibrometry and electrophysiology to determine whether the song spectra, the best frequencies of tympanal-membrane vibrations and the threshold curves of the tympanal nerves are adapted to one another. The songs of almost all species have a relatively broad-band maximum in the region between 20 and 40 kHz and a narrower peak between 5 and 15 kHz. There are clear interspecific differences in the latter, which are not correlated with the length of the body or of the elytra. At the site of attachment of the low-frequency receptors (a-cells), the tympanal membrane oscillates with maximal amplitude in the region from 5 to 10 kHz. At the attachment site of the high-frequency receptors (d-cells), there is also a maximum in this region as well as another around 15-20 kHz. The tympanal nerve is most sensitive to tones between 5 and 10 kHz, with another sensitivity maximum between 25 and 35 kHz. The species may differ from one another in the position of the low-frequency peaks of the membrane oscillation, of the nerve activity and of the song spectra. No correlation was found between the characteristic frequency of the membrane oscillation and the area of the tympanal membrane. Within a given species, the frequency for maximal oscillation of the membrane at the attachment site of the low-frequency receptors and the frequency for maximal sensitivity of the tympanal nerve are in most cases very close to the low-frequency peak in the song spectrum. In the high-frequency range, the situation is different: here, the position of the peak in the song spectrum is not correlated with the membrane oscillation maximum at the attachment site of the high-frequency receptors, although there is a correlation between the song spectrum and the sensitivity of the tympanal nerve. On the whole, therefore, hearing in acridid grasshoppers is quite well adjusted to the frequency spectra of the songs, partly because the tympanal membrane acts as a frequency filter in the low-frequency range.

scholarly journals Uneven distribution of Y-chromosome haplogroups in the regional populations of ukrainians

2018 ◽  
Vol 23 ◽  
pp. 232-237
Author(s):  
O. M. Utevska ◽  
L. A. Atramentova
Keyword(s):  
Y Chromosome ◽  
Frequency Distribution ◽  
High Frequency ◽  
Gene Pool ◽  
Low Frequency ◽  
Snp Markers ◽  
Uneven Distribution ◽  
Haplogroup Frequency ◽  
Frequency Spectra

Aim. The aim was to compare the frequency spectra of Y chro mosome haplogroups among Ukrainians from different regions, identify atypical populations and determine their characteristics. Methods. A sample of Ukrainians (n = 1141) from 12 regions of Ukraine was investigated. DNA samples were genotyped by the SNP markers of the Y chromosome. The frequencies of Y chromosome haplogroups for the regions were compared using the χ2 and F tests. Results. Differences between regions in the haplogroup frequency distribution were determined, atypical populations were detected, and the features of their Y-chromosome spectrum were studied. Conclusions. Lviv and Rivne samples were the closest to frequencies of Y-chromosome haplogroups averaged for Ukraine. The highest specificity was found in samples from Khmelnitska (R-M198(×M458) high frequency, R-M458 low frequency), Zaporozhska (E-M78 absence) and Chernigov (R-M458 high frequency, R-M198(×M458) low frequency) regions. Keywords: Y-chromosome, haplogroup, Ukrainians, gene pool.

scholarly journals Динамика магнитных скирмионов в наноточках

2018 ◽  
Vol 60 (6) ◽  
pp. 1135
Author(s):  
З.В. Гареева ◽  
К.Ю. Гуслиенко
Keyword(s):  
Ultrathin Films ◽  
High Frequency ◽  
Linear Array ◽  
Linear Chain ◽  
Low Frequency ◽  
Characteristic Difference ◽  
Frequency Spectra ◽  
High Frequency Excitation ◽  
Frequency Excitation ◽  
Magnetic Skyrmions

AbstractBloch and Neel magnetic skyrmions have been studied in systems of confined geometry (nanodots, a linear array of nanodots). The spectra of low- and high-frequency excitation modes of a skyrmion state have been calculated. It has been shown that skyrmion spectrum asymmetry, namely, the characteristic difference between the frequencies of the azimuthal modes of the azimuthal skyrmion modes rotating clockwise and counterclockwise, is associated with asymmetry in the magnetization profiles of high-frequency spin waves propagating on the background of a skyrmion state in a nanodot. The low-frequency spectrum contains the only gyrotropic mode localized near the center of a nanodot. The gyrotropic frequency depends on the material parameters of a nanodot and the size of a skyrmion. The eigenfrequency of the gyrotropic mode of an isolated skyrmion in a nanodot in ultrathin films ( L ~ 1 nm) does not depend on the internal structure of a skyrmion and is the same for Bloch and Neel skyrmions. The interaction of skyrmions, in particular, in a linear chain of nanodots with the ground skyrmion state, leads to distinctions in low-frequency spectra. The structure of a skyrmion (of Bloch or Neel type) is exhibited as a shift of dispersion curves and a difference between the frequencies of ferromagnetic resonance in a system of interacting skyrmions.

Simulations of high-resolution images of amorphous silicon films

1986 ◽  
Vol 44 ◽  
pp. 544-545
Author(s):  
G. Y. Fan ◽  
J. M. Cowley
Keyword(s):  
Electron Microscope ◽  
High Frequency ◽  
Fourier Transformation ◽  
Amorphous Materials ◽  
Low Frequency ◽  
Chromatic Aberration ◽  
Structure Information ◽  
Frequency Components ◽  
High Resolution Images ◽  
Spatial Frequency Spectrum

It is well known that the structure information on the specimen is not always faithfully transferred through the electron microscope. Firstly, the spatial frequency spectrum is modulated by the transfer function (TF) at the focal plane. Secondly, the spectrum suffers high frequency cut-off by the aperture (or effectively damping terms such as chromatic aberration). While these do not have essential effect on imaging crystal periodicity as long as the low order Bragg spots are inside the aperture, although the contrast may be reversed, they may change the appearance of images of amorphous materials completely. Because the spectrum of amorphous materials is continuous, modulation of it emphasizes some components while weakening others. Especially the cut-off of high frequency components, which contribute to amorphous image just as strongly as low frequency components can have a fundamental effect. This can be illustrated through computer simulation. Imaging of a whitenoise object with an electron microscope without TF limitation gives Fig. 1a, which is obtained by Fourier transformation of a constant amplitude combined with random phases generated by computer.

SEM image sharpness analysis

1996 ◽  
Vol 54 ◽  
pp. 142-143
Author(s):  
M. T. Postek ◽  
A. E. Vladar
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Quantitative Information ◽  
Primary Electron ◽  
Image Sharpness ◽  
Critical Dimensions ◽  
Sem Image ◽  
Frequency Changes ◽  
Electron Microscopes ◽  
Scanning Electron

Fully automated or semi-automated scanning electron microscopes (SEM) are now commonly used in semiconductor production and other forms of manufacturing. The industry requires that an automated instrument must be routinely capable of 5 nm resolution (or better) at 1.0 kV accelerating voltage for the measurement of nominal 0.25-0.35 micrometer semiconductor critical dimensions. Testing and proving that the instrument is performing at this level on a day-by-day basis is an industry need and concern which has been the object of a study at NIST and the fundamentals and results are discussed in this paper.In scanning electron microscopy, two of the most important instrument parameters are the size and shape of the primary electron beam and any image taken in a scanning electron microscope is the result of the sample and electron probe interaction. The low frequency changes in the video signal, collected from the sample, contains information about the larger features and the high frequency changes carry information of finer details. The sharper the image, the larger the number of high frequency components making up that image. Fast Fourier Transform (FFT) analysis of an SEM image can be employed to provide qualitiative and ultimately quantitative information regarding the SEM image quality.

Real Ear Sound Pressure Levels Developed by Three Portable Stereo System Earphones

1992 ◽  
Vol 1 (4) ◽  
pp. 52-55 ◽  
Author(s):  
Gail L. MacLean ◽  
Andrew Stuart ◽  
Robert Stenstrom
Keyword(s):  
High Frequency ◽  
Sound Pressure ◽  
Low Frequency ◽  
Test System ◽  
Output Frequency ◽  
Frequency Effects ◽  
Adult Men ◽  
Frequency Responses ◽  
Significant Difference ◽  
Sound Pressure Levels

Differences in real ear sound pressure levels (SPLs) with three portable stereo system (PSS) earphones (supraaural [Sony Model MDR-44], semiaural [Sony Model MDR-A15L], and insert [Sony Model MDR-E225]) were investigated. Twelve adult men served as subjects. Frequency response, high frequency average (HFA) output, peak output, peak output frequency, and overall RMS output for each PSS earphone were obtained with a probe tube microphone system (Fonix 6500 Hearing Aid Test System). Results indicated a significant difference in mean RMS outputs with nonsignificant differences in mean HFA outputs, peak outputs, and peak output frequencies among PSS earphones. Differences in mean overall RMS outputs were attributed to differences in low-frequency effects that were observed among the frequency responses of the three PSS earphones. It is suggested that one cannot assume equivalent real ear SPLs, with equivalent inputs, among different styles of PSS earphones.

Evaluation of Special Hearing Aids for Deaf Children

1971 ◽  
Vol 36 (4) ◽  
pp. 527-537 ◽  
Author(s):  
Norman P. Erber
Keyword(s):  
Hearing Aids ◽  
High Frequency ◽  
Hearing Aid ◽  
Low Frequency ◽  
Acoustic Stimulation ◽  
Deaf Children ◽  
Frequency Range ◽  
Frequency Limit ◽  
Unpublished Studies ◽  
Published Research

Two types of special hearing aid have been developed recently to improve the reception of speech by profoundly deaf children. In a different way, each special system provides greater low-frequency acoustic stimulation to deaf ears than does a conventional hearing aid. One of the devices extends the low-frequency limit of amplification; the other shifts high-frequency energy to a lower frequency range. In general, previous evaluations of these special hearing aids have obtained inconsistent or inconclusive results. This paper reviews most of the published research on the use of special hearing aids by deaf children, summarizes several unpublished studies, and suggests a set of guidelines for future evaluations of special and conventional amplification systems.

Heart Rate Variability, Emotions, and Music

2010 ◽  
Vol 24 (2) ◽  
pp. 112-119 ◽  
Author(s):  
F. Riganello ◽  
A. Candelieri ◽  
M. Quintieri ◽  
G. Dolce
Keyword(s):  
Data Mining ◽  
Heart Rate ◽  
Heart Rate Variability ◽  
Vegetative State ◽  
Low Frequency ◽  
Emotional Reactions ◽  
Heart Beat ◽  
Healthy Controls ◽  
Frequency Spectra ◽  
Emotional Value

The purpose of the study was to identify significant changes in heart rate variability (an emerging descriptor of emotional conditions; HRV) concomitant to complex auditory stimuli with emotional value (music). In healthy controls, traumatic brain injured (TBI) patients, and subjects in the vegetative state (VS) the heart beat was continuously recorded while the subjects were passively listening to each of four music samples of different authorship. The heart rate (parametric and nonparametric) frequency spectra were computed and the spectra descriptors were processed by data-mining procedures. Data-mining sorted the nu_lf (normalized parameter unit of the spectrum low frequency range) as the significant descriptor by which the healthy controls, TBI patients, and VS subjects’ HRV responses to music could be clustered in classes matching those defined by the controls and TBI patients’ subjective reports. These findings promote the potential for HRV to reflect complex emotional stimuli and suggest that residual emotional reactions continue to occur in VS. HRV descriptors and data-mining appear applicable in brain function research in the absence of consciousness.

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