scholarly journals ANALYSIS OF HIGH FREQUENCY BREAKING WAVES AND LOW FREQUENCY SURGES GENERATED IN HARBORS DUE TO PASSAGE OF DEEP-DRAFT TANKERS

2018 ◽  
pp. 27
Author(s):  
Arpit Agarwal ◽  
Scott Fenical ◽  
Kirsten McElhinney ◽  
Paul Carangelo ◽  
David Krams
Keyword(s):  
High Frequency ◽  
Pressure Field ◽  
Low Frequency ◽  
Breaking Waves ◽  
Wave Activity ◽  
The West ◽  
Ship Traffic ◽  
Corpus Christi ◽  
Navigation Channel ◽  
Over Time

Cline’s Point Marina, located in Port Aransas, TX, has been experiencing detrimental conditions near the marina’s entrance and within the marina itself during the passage of deep-draft ship traffic. The wave activity is primarily generated by pressure field effects from large, laden outbound vessels in Corpus Christi Ship Channel (CCSC). The basin was originally protected by an approximately 180 ft. long breakwater constructed in 1976 on the west side of the entrance which by 1980 has deteriorated and partially failed to 120 ft. long breakwater and continued deteriorating over time, reaching its approximate 60 ft. long current condition by 2003. The deterioration of this breakwater has reportedly resulted in enhanced penetration of deep-draft vessel wave activity into the marina (Figure 1). Mott MacDonald (MM) evaluated the mechanisms by which waves are generated in the navigation channel, transform, and enter the harbor, quantified the level of protection afforded by past and present entrance breakwater configuration(s), and developed conceptual alternatives for improving conditions inside the marina.

Naturalistic Study of the use of Transcranial Magnetic Stimulation in the Treatment of Depressive Relapse

2006 ◽  
Vol 40 (9) ◽  
pp. 764-768 ◽  
Author(s):  
Paul B. Fitzgerald ◽  
Jessica Benitez ◽  
Anthony R. De Castella ◽  
Timothy L. Brown ◽  
Z. Jeff Daskalakis ◽  
...  
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
High Frequency ◽  
Magnetic Stimulation ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Low Frequency ◽  
Naturalistic Study ◽  
Treatment Of Depression ◽  
Long Term Impact ◽  
Over Time

Background: The efficacy of repetitive transcranial magnetic stimulation (rTMS) in the treatment of depression has been assessed in a number of acute treatment trials during the last 10 years. Little is known about the long-term impact of the treatment on the disorder and its effectiveness when applied for repeated relapses of depression over time. Method: Nineteen patients who had previously responded to rTMS in clinical trials received treatment with rTMS for a total of 30 episodes of depressive relapse. Results: Approximately 10 months elapsed between treatment episodes. The majority of patients achieved a significant improvement in each treatment course with significant improvements achieved in patients treated with both low-frequency right-sided rTMS and high-frequency left-sided rTMS. Conclusions: The study suggests that rTMS may have value in the treatment of episodes of depressive relapse with little reduction in efficacy over time.

scholarly journals Frequent handling of grazing beef cattle maintained under the rotational stocking method improves temperament over time

2018 ◽  
Vol 58 (2) ◽  
pp. 307 ◽  
Author(s):  
Maria C. Ceballos ◽  
Karen Camille R. Góis ◽  
Aline C. Sant'Anna ◽  
Mateus J. R. Paranhos da Costa
Keyword(s):  
Beef Cattle ◽  
High Frequency ◽  
Low Frequency ◽  
Flight Speed ◽  
Grazing System ◽  
Grazing Period ◽  
Animal Handling ◽  
Over Time ◽  
Reactivity Score

Our aims were to assess the effects of handling frequency on temperament evolution in cattle kept under rotational stocking method (RSM), as well as to compare the temperament of animals maintained under rotational versus alternate stocking (ASM) methods. We evaluated 4256 males raised on pasture from four private properties (Farms 1–4), for a total of 9628 observations. The study was divided into two complementary approaches. In the first one, monthly visits were conducted at 35-day intervals to assess the cattle temperament (n = 1979) raised on grazing system using RSM, while, in the second approach, we evaluated the temperament of cattle (n = 3600) kept under two different stocking methods, namely, (1) RSM (n = 2007), characterised by a high frequency of animal handling and a 4-day grazing period, and (2) ASM (n = 1593), characterised by a low frequency of handling and a 20-day grazing period. Composite reactivity score (RS), and flight speed (FS) were considered as temperament indicators. Reductions of RS and FS means were observed during successive assessments under RSM. Significant effects of stocking method on FS (P < 0.05) and RS (P < 0.01) were found, with lower FS and RS means for animals under RSM than for those under ASM. In conclusion, the frequent handling in the rotational stocking method favoured the improvement of cattle temperament over time, with lower levels of reactivity among cattle raised under this stocking method than with animals raised under the alternate stocking method.

Spatial distribution of low-frequency earthquakes suggestive of geofluid among the aftershocks of the 2008 Iwate-Miyagi Nairiku Earthquake in northeastern Japan

2020 ◽  
Author(s):  
Masahiro Kosuga
Keyword(s):  
Stress Field ◽  
Pore Pressure ◽  
High Frequency ◽  
Low Frequency ◽  
Local Stress ◽  
Ductile Deformation ◽  
Stress Axis ◽  
Upper Crust ◽  
The West ◽  
Northeastern Japan

&lt;p&gt;In northeastern Japan, low-frequency earthquakes (LFEQs) occur preferentially at depths from the lower crust to the uppermost mantle near the active volcanoes. Many researchers have suggested the contribution of geofluid to the occurrence of these unusually deep LFEQs. Recent observations show that relatively low-frequency earthquakes occur even in the upper crust as well. Investigation of the generation mechanism of shallow LFEQs is quite important because it is directly related to the mechanism of closely located high-frequency earthquakes in the brittle upper crust. One of the areas of enhanced shallow LFEQ seismicity is the aftershock zone of the 2008 Iwate-Miyagi Nairiku Earthquake (Mw 6.8) located to the west of the 2011 great Tohoku earthquake. We detected LFEQs by using the frequency index (FI) defined by the logarithm of a ratio of high- and low-frequency spectral amplitudes. We used 2&amp;#8211;4 Hz and 10&amp;#8211;20 Hz bands for low- and high-frequency ranges. We analyzed more than 4000 events observed by a dense temporary seismic network deployed just after the occurrence of the mainshock. Our detection revealed that there are five LFEQs dominant clusters in the aftershock zone trending NNE-SSW with a length of about 40 km: the northern and the southern edge of the aftershock zone, to the north of the mainshock epicenter, the eastern and western edge of the central aftershock zone. In the area near the mainshock epicenter, hypocenter distribution shows two planes: mainshock fault dipping to the west and a conjugate fault dipping to the east. The previous study has shown that the events with N-S trending largest principle stress axis are distributed along the conjugate plane. In contrast, the events along the mainshock fault have E-W trending largest principle axis that is consistent with the relative motion of the subducting Pacific plate beneath the Tohoku region. The former anomalous groups are interpreted to be caused by local stress change by the mainshock applied to a neutral stress field with high pore pressure suggested by high Vp/Vs ratio. An interesting feature is the preferential distribution of LFEQs along the conjugate plane. Also, the hypocenter of LFEQs migrated with time from deeper to the shallower part of the plane. These observations strongly suggest that the existence and movement of geofluid are responsible for both the unusual stress field and the occurrence and migration of LFEQs. The location of LFEQs at the northern and eastern edge of the aftershock zone is close to the areas of postseismic slip detected by GNSS observation, which is suggestive of the increased pore pressure in the area. The LFEQs at the southern and western edge of the aftershock zone occur in calderas, suggesting that these LFEQs occur in hotter and/or fluid-rich areas where the ductile deformation occurs. Thus, though the interpretation of the cause of LFEQs is not unique, the distribution of LFEQs plays a crucial role in understanding the contribution of geofluids not only to the seismogenic processes of aftershocks but to the faulting mechanism in the upper crust.&lt;/p&gt;

Determination of Site Response in Anchorage, Alaska, on the Basis of Spectral Ratio Methods

2002 ◽  
Vol 18 (1) ◽  
pp. 85-104 ◽  
Author(s):  
A. Martirosyan ◽  
U. Dutta ◽  
N. Biswas ◽  
A. Papageorgiou ◽  
R. Combellick
Keyword(s):  
Shear Wave ◽  
Shear Wave Velocity ◽  
High Frequency ◽  
Site Response ◽  
Low Frequency ◽  
Spectral Ratio ◽  
Frequency Range ◽  
The West ◽  
Site Coefficients ◽  
Average Shear

This paper deals with the site response (SR) in the Anchorage basin in south-central Alaska. The investigation is based on the analysis of seismograms of 114 earthquakes recorded by 22 weak-motion stations and 46 earthquakes recorded by 19 strong-motion stations in the study area. We have computed SR for 41 sites, using standard spectral ratio and horizontal-to-vertical spectral ratio methods in the frequency range from 0.5 to 11 Hz. Based on these results, we have calculated band-average site response values in two frequency ranges: low frequency (from 0.5 to 2.5 Hz) and high frequency (from 3 to 7 Hz). There is a good correlation between SR values and surficial geology of the Anchorage area in the low-frequency range. SR values increase by a factor of three from the foothills of the Chugach Mountains in the east to the west towards the deeper part of the basin. The highest site response values (SR>2.5) in the same frequency range are observed in the west-central part of the city, which is underlain by cohesive facies of the Bootlegger Cove formation. The SR has a good correlation with the uppermost 30-m time-average shear-wave velocity with a correlation coefficient of 0.82. Moreover, the low-frequency SR values are close to the NEHRP site coefficients for 1 sec. However, high-frequency SR values lack correlation with 30-m average shear-wave velocity and short-period NEHRP site coefficients.

scholarly journals Memory resources recover gradually over time: The effects of word-frequency, presentation rate and list-composition on binding errors and mnemonic precision in source memory

2019 ◽  
Author(s):  
Vencislav Popov ◽  
Matthew So ◽  
Lynne Reder
Keyword(s):  
Word Frequency ◽  
High Frequency ◽  
Continuous Distribution ◽  
Low Frequency ◽  
Presentation Rate ◽  
Frequency Effect ◽  
Word Frequency Effect ◽  
Reproduction Task ◽  
Memory Precision ◽  
Over Time

Normative word frequency has played a key role in the study of human memory, but there is little agreement as to the mechanism responsible for its effects. To determine whether word frequency affects binding probability or memory precision, we used a continuous reproduction task to examine working memory for spatial positions of words. In three experiments, after studying a list of five words, participants had to report the spatial location of one of them on a circle. Across experiments we varied word frequency, presentation rate and the proportion of low frequency words on each trial. A mixture model dissociated memory precision, binding failure and guessing rate parameters from the continuous distribution of errors. On trials that contained only low- or only high-frequency words, low-frequency words lead to a greater degree of error in recalling the associated location. This was due to a higher word-location binding failure and not due to differences in memory precision or guessing rates. Slowing down the presentation rate eliminated the word frequency effect by reducing binding failures for low-frequency words. Mixing frequencies in a single trial hurt high-frequency and helped low-frequency words. These findings support the idea that word frequency can lead to both positive and negative mnemonic effects depending on a trade-off between a HF encoding advantage and a LF retrieval cue advantage. We suggest that 1) low-frequency words require more resources for binding, 2) that these resources recover gradually over time, and that 3) binding fails when these resources are insufficient.

scholarly journals Beauty and Ugliness of Aggregation over Time: A Survey

2017 ◽  
Vol 68 (3) ◽  
Author(s):  
Nlandu Mamingi
Keyword(s):  
Public Policy ◽  
Time Series ◽  
High Frequency ◽  
Low Frequency ◽  
High Frequency Data ◽  
Frequency Data ◽  
Economic Time Series ◽  
Negative Effects ◽  
Economic Time ◽  
Over Time

AbstractThis paper delivers an up-to-date literature review dealing with aggregation over time of economic time series, e.g. the transformation of high-frequency data to low frequency data, with a focus on its benefits (the beauty) and its costs (the ugliness). While there are some benefits associated with aggregating data over time, the negative effects are numerous. Aggregation over time is shown to have implications for inferences, public policy and forecasting.

Heart Rate Variability in Premature Infants During Feeding

2007 ◽  
Vol 8 (4) ◽  
pp. 283-293 ◽  
Author(s):  
Lisa Brown
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Feeding Behavior ◽  
Infant Feeding ◽  
Premature Infants ◽  
High Frequency ◽  
Low Frequency ◽  
Research Attention ◽  
Physiologic Regulation ◽  
Over Time

Early mother-infant interaction, a potentially major contributor to the development of a premature infant's behavioral and physiologic regulation, has received very little research attention. This study examined the development of physiologic regulation in relation to maternal-infant feeding interaction for 43 premature infants, from the time caregiving responsibility was transferred to the mother through each infant's 4th postterm month. Infants and mothers were seen in a special care nursery just before discharge and in home at 1 and 4 months postterm age. General linear mixed models were used to examine the changes in infant heart rate variability (HRV) and Positive Affective Involvement and Sensitivity/Responsiveness scores over time and infant HRV over feeding conditions (prefeeding, feeding, and postfeeding). Significant differences were found for high-frequency and low-frequency HRV over time (p < .001 and p = .014, respectively). However, maternal feeding behavior did not show a significant effect of time (p = .24). The feeding condition effect on high-frequency HRV was significant (p < .001), with HRV lower during feeding compared to both prefeeding and postfeeding. Maternal feeding behavior was not associated with infant HRV. Discovering the ways in which maternal feeding behavior contributes to infant physiologic regulation may require study of the relationship of HRV to infant feeding behavior.

scholarly journals Roles of Low- and High-Frequency Eddies in the Transitional Process of the Southern Hemisphere Annular Mode

2005 ◽  
Vol 18 (6) ◽  
pp. 782-794 ◽  
Author(s):  
Hideo Shiogama ◽  
Toru Terao ◽  
Hideji Kida ◽  
Tatsuya Iwashima
Keyword(s):  
Pacific Ocean ◽  
Southern Hemisphere ◽  
High Frequency ◽  
Momentum Flux ◽  
Rossby Waves ◽  
Low Frequency ◽  
Wave Activity ◽  
Transitional Process ◽  
The Pacific ◽  
The Pacific Ocean

Abstract The effects of low- and high-frequency eddies (time scales longer and shorter than 10 days, respectively) on the transitional processes of the Southern Hemisphere “Annular Mode” are investigated, based on NCEP–NCAR daily reanalysis data for the period 1979–2001. Special attention is focused on the zonal symmetry/asymmetry and the temporal evolution of the eddy forcing. For the poleward transitional process, the effects of low-frequency eddies precede those of high-frequency eddies in driving the jet transition. Quasi-stationary Rossby waves propagating along the polar jet with wavelengths of 7000 km play an important role. The waves, originally come from the Indian Ocean through the waveguide associated with the polar jet, dissipate equatorward over the eastern Pacific Ocean. This anomalous equatorward dissipation of wave activity induces an anomalous poleward momentum flux, which is responsible for changes in the polar jet over the Pacific Ocean during the beginning stage. Following the low-frequency eddy forcing, momentum forcing anomalies due to the high-frequency eddies rapidly appear. This forcing continues to drive the polar jet poleward over the whole of longitude, while the low-frequency eddies have completed their role of inducing the anomalous poleward momentum flux during the earlier stage. For the equatorward transitional events, the roles of the low-frequency eddy forcing differ from that in the poleward ones. Anomalous equatorward momentum fluxes due to low-frequency eddies appear simultaneously with that due to high-frequency eddies. Quasi-stationary Rossby waves with wavelengths of 7000 km propagate southeastward through the waveguide over the Pacific Ocean. The convergence of their wave activity results in the deceleration of the westerlies over the higher latitudes of the Pacific Ocean. On the other hand, the high-frequency eddy forcing contributes to the equatorward jet drift longitudinally over the whole of the hemisphere.

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.

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