Long-period Range Research Articles

Neuronal control of energy homeostasis

Neuronal control of body energy homeostasis is the key mechanism by which animals and humans regulate their long-term energy balance. Various hypothalamic neuronal circuits (which include the hypothalamic melanocortin, midbrain dopamine reward and caudal brainstem autonomic feeding systems) control energy intake and expenditure to maintain body weight within a narrow range for long periods of a life span. Numerous peripheral metabolic hormones and nutrients target these structures providing feedback signals that modify the default “settings” of neuronal activity to accomplish this balance. A number of molecular genetic tools for manipulating individual components of brain energy homeostatic machineries, in combination with anatomical, electrophysiological, pharmacological and behavioral techniques, have been developed, which provide a means for elucidating the complex molecular and cellular mechanisms of feeding behavior and metabolism. This review will highlight some of these advancements and focus on the neuronal circuitries of energy homeostasis.

Candidate SPB and γ Doradus stars from microlensing surveys

From the analysis of the database of 200 000 variable candidates in the OGLE-II Galactic fields we have extracted about 600 stars showing periodic low-amplitude brightness variations. Many of them are multiperiodic. From their location in the colour-magnitude diagram we conclude that they are good candidates for slowly pulsating B and γ Doradus stars. The data and analysis Using data from the catalogue of 200 000 variable stars candidates we searched short-period low-amplitude pulsators. This photometry was accumulated during the OGLE–II project carried out in the years 1997–2000 in the 49 fields located near the centre of the Galaxy (Woźniak et al. 2002). The analysis consisted of an automatic extraction of up to five periodic terms for all stars in the catalogue with consecutive prewhitening followed by an automatic classification based upon the periods, amplitudes and Fourier coefficients (for stars with detected harmonics or subharmonics). Then, for stars selected in this way, a detailed analysis was performed in an interactive way. The analysis yielded a lot of candidates for β Cephei and δ Scuti stars (Narwid et al. 2006). In addition, we detected a sample of over 600 low-amplitude variable stars with periods in the range between 0.5 and 6 days. We suspect that the sample consists mainly of a mixture of SPB and γ Doradus stars. For 270 of the variables, we were able to combine the OGLE-II data with the photometry available from the MACHO survey. The analysis of the combined photometry resulted in better resolution, lower detection threshold and practically removed the ambiguity in the frequencies of the detected periodicities. No transformations were performed before data combination. The results and conclusions The results we obtained can be summarized in the following way. The position in the colourmagnitude diagram (CMD) clearly suggests that these stars are main-sequence pulsators. Their V magnitudes range from 12 to 18 mag. The distribution of periods shows that most of these stars have periods in the range between 0.55 and 1.5 d; for periods longer than 2.5 d the number of variables decreases with increasing period. The I-filter semi-amplitudes of the variables are typically below 20 mmag, but there are stars with semi-amplitudes of up to 90 mmag. The brightness variability with periods from the aforementioned range is typical for candidate SPB and γ Doradus stars. Thus, we suppose that our sample consists mainly of a mixture of these two types of pulsators. This conclusion is supported by the fact that about 400 stars in our sample show multiperiodic behaviour. Up to seven modes in a single star were found in the combined OGLE-II and MACHO data. In the long-period range contamination from the other types of variability, e.g. α2 CVn stars or ellipsoidal binaries, cannot be excluded. In a few stars we also revealed periodicities with periods shorter than 0.5 d. Such periods are more typical for δ Scuti or β Cephei-type 182 Candidate SPB and γ Doradus stars from microlensing surveys variability. These stars are therefore good candidates for hybrid γ Doradus/δ Scuti stars similar to HD 8801 (Henry & Fekel 2005). Another possibility is that they are hybrid SPB/β Cephei stars. The periods, amplitudes and the position in the CMD are not sufficient to distinguish SPBs from γ Doradus stars. Therefore we are going to gather UBV photometry and/or low-resolution spectroscopy for stars from our sample, which will allow us to improve the classification of these stars. Acknowledgments. This work was supported by the MNiI grant No. 1 P03D 016 27. The authors are grateful to the EC for the establishment of the European Helioand Asteroseismology Network HELAS, which made their participation at this workshop possible.

국내 지반특성에 적합한 지반분류 방법 및 설계응답스펙트럼 개선에 대한 연구 (III) - 설계응답스펙트럼 개선방법

동반논문(II-지반분류 개선방법)에서는 지반의 고유주기를 기준으로 지반을 분류하는 방법이 국내 지반조건에 적합한 지반분류 방법으로 제시하였다. 그러나, 지반분류 방법을 개선하여도 해석결과의 평균 스펙트럼 가속도 값과 재산정된 응답스펙트럼과 차이가 나타나는 부분이 존재한다. 이는 설계응답스펙트럼을 작성에 필요한 증폭계수를 계산하는 방법을 변경해야 해결할 수 있다. 본 논문에서는 국내 지반조건에 적합하도록 증폭계수를 재산정하기 위한 적분구간 변경에 대하여 검토하였다. 검토 결과 장주기 영역의 증폭계수 <TEX>$F_v$</TEX>의 적분구간은 현재 주기 0.4초<TEX>${\sim}$</TEX>2.0초에서 주기 0.4초<TEX>${\sim}$</TEX>1.5초로 변경할 경우 해석결과의 평균 스펙트럼 가속도 값과 설계응답스펙트럼이 비교적 잘 일치하는 결과를 얻을 수 있었고, 기존의 방법보다 국내 지반특성에 더 적합한 설계응답스펙트럼을 작성할 수 있었다. In the companion paper (II, Development of Site Classification System), new size classification system based on site periods <TEX>$(T_G)$</TEX> was recommended for legions of shallow bedrock depth in Korea. Despite the site classification method was improved, the response spectrum would be required to be modified by adjusting the integration interval to calculate the site coefficients because the response spectra did not match well the average spectral accelerations obtained by site response analyses in the range of long periods. In this paper, new response spectra for each site categories were determined by adjusting the integration interval of long period site coefficient <TEX>$F_v\;from\;0.4{\sim}2.0\;to\;0.4{\sim}1.5$</TEX> second. It matched well the average spectral accelerations and new response spectrum, and it was also improved compared to the current she classification system.

Classical Cepheid Pulsation Models. X. The Period‐Age Relation

We present new period-age (PA) and period-age-color (PAC) relations for fundamental and first-overtone classical Cepheids. Current predictions rely on homogeneous sets of evolutionary and pulsation models covering a broad range of stellar masses and chemical compositions. We found that PA and PAC relations present a mild dependence on metal content. Moreover, the use of different PA and PAC relations for fundamental and first-overtone Cepheids improves the accuracy of age estimates in the short-period (log P < 1) range (old Cepheids), because they present smaller intrinsic dispersions. At the same time, the use of the PAC relations improves the accuracy in the long-period (log P ≥ 1) range (young Cepheids), since they account for the position of individual objects inside the instability strip. We performed a detailed comparison between evolutionary and pulsation ages for a sizable sample of LMC (15) and SMC (12) clusters which host at least two Cepheids. In order to avoid deceptive uncertainties in the photometric absolute zero point, we adopted the homogeneous set of B, V, and I data for clusters and Cepheids collected by OGLE. We also adopted the same reddening scale. The different age estimates agree at the level of 20% for LMC clusters and of 10% for SMC clusters. We also performed the same comparison for two Galactic clusters (NGC 6067, NGC 7790), and the difference in age is smaller than 20%. These findings support the use of PA and PAC relations to supply accurate estimates of individual stellar ages in the Galaxy and in external Galaxies. The main advantage of this approach is its independence from the distance.

Retrofitting Suspension Bridges Using Distributed Dampers

Suspension bridges in the Central and Eastern United States (CEUS) were built before recent advances in earthquake engineering, and may be susceptible to seismic ground motions. In this article, a retrofit strategy is proposed in which damping devices are distributed throughout the suspended truss structure in order to reduce the bridge response. Six ground motions suites are assembled: three synthetic motion suites representing expected CEUS motions, with special attention paid to the long-period range. The three remaining motions are recordings of actual events. A finite element model of a suspension bridge typical of those found in the CEUS was subjected to the assembled ground motions both in a baseline and retrofitted condition. The proposed retrofit strategy successfully reduced the demands on both the superstructure and substructure of the subject bridge. Specific locations for the damping devices were identified as being especially effective. The inclusion of spatial variations in the input ground motions can have a large effect on the response. The method may be useful for mitigating dynamic responses caused by wind.

Displacement Spectra for Long Periods

Using selected sets of high-quality digital strong motion data from different regions (Taiwan, Japan, Italy, and Greece), the salient features of displacement response spectra in the long-period range are illustrated (up to 10 s period) as a function of magnitude, source distance, and site conditions. By means of simple analytical models of displacement waveforms, we have derived analytical expressions for the displacement spectra that provide satisfactory fits to the observations. These expressions also demonstrate that the moment magnitude and distance control the shape of the spectra consistent with the commonly accepted models of the seismic source. Furthermore, we derived from simple physical considerations an analytical expression of the variation of peak ground displacement with magnitude and distance that reasonably fits the observations. The findings of this study are believed to be particularly useful in the formulation of design elastic displacement spectra for seismic codes, and in zoning studies of seismic hazard for long-period structures.

A Comprehensive Interpretation of Strong Motions in the Mexican Volcanic Belt

Large-amplitude seismograms with extremely long duration have been recorded in the Valley of Mexico. Recently, we came to recognize important effects of the Mexican Volcanic Belt (MVB) on the seismograms. We interpret strong motions observed in the MVB by analyzing the three components of surface and borehole accelerograms recorded during the 14 September 1995 earthquake ( M S 7.3). The target period range is between 0.1 and 10.0 sec, with emphasis on a 2.0- to 3.0-sec period range. In the lake-bed zone inside the valley, wave types of seismic motions are identified by calculating theoretical amplification of various seismic waves and cross-correlation functions between surface and borehole recordings. In the MVB, propagation velocities of dominant surface waves are estimated by analyses of recordings and are compared with theoretical velocities, and 2D/3D wave-propagation simulations for the MVB and the Mexico City Basin are performed. Our conclusions are the following. (1) We suggest that, while strong motions observed in the lake-bed zone are a mixture of P, S , Love, and Rayleigh waves, fundamental-mode Love waves are dominant. (2) Surface waves are found to be much more heavily amplified than S waves in the soft lake-bed deposit. (3) We confirm that the MVB is an important structure to amplify seismic motions. The lake-bed deposit, together with the basin structure, proves to remarkably amplify surface waves. (4) In the lake-bed deposit, quality factors are found to be about 3 in the long-period range of more than 1.5 sec. Manuscript received 24 March 2003.

BODY CONDITION AND PARENTAL DECISIONS IN THE SNOW PETREL (PAGODROMA NIVEA)

Abstract In Procellariiformes, parents guard the chick for some time after it has attained homeothermy. Such a strategy may have evolved to protect the chick from predation or inclement weather, but it is costly because only one parent can forage at a time. Therefore, the decision to leave the chick seems to be a trade-off between the chick's ability to care for itself, body condition of the parent present at the nest, and ability of the bird out foraging to return to the nest before its mate's body condition has degraded. We studied chick growth and survival together with number of days Snow Petrel (Pagodroma nivea) chicks were guarded before being left alone for the first time in relation to the parents body condition and ability to return to the nest in time. Parents in good body condition were more likely to produce a chick that survived the guard stage. They also guarded their chick for a longer period (range 2–8 days, x = 4.5) and finally left it alone with a higher body mass than those in poor bod...

A Study of Strong Motion Response Spectrum in West-central Taiwan

In this paper, a total of 901 free-field accelerograms recorded at the stations in west-central Taiwan from 32 earthquakes that occurred in Taiwan area between 1993 and 1999 are separated as four data groups based on PGA levels, the station sites are classified into three types by their dominant periods of acceleration response spectra. The characteristics of response spectra in regard to both earthquake intensity and station type are analyzed. In order to highlight the behavior of the Chi-Chi mainshock, several kinds of comparisons of the near-fault responses have been made with those of far-field data. The results show that the response spectra increase generally with the earthquake intensity for all stations. The spectral shape in long period regions become more predominant if the soil condition is softer. The mean response spectra plus one standard-deviation of the Chi-Chi mainshock are significantly larger than the required values of the current seismic design code. In terms of the long-period range, the spectra of the Chi-Chi mainshock are larger than the mean value of 32 events by more than 200 times. The spectral ratios of vertical to horizontal component almost exceed 2/3; this phenomenon reflects the intensified vertical ground motion due to the thrusting movement of the Chelungpu fault. Therefore, a modified design code is suggested for applications to near-fault areas.

Using thermal ecology to predict retreat-site selection by an endangered snake species

Many ectotherms spend long periods in retreat-sites, where thermal conditions may strongly influence key physiological or behavioural processes (e.g. locomotion, digestion, growth rates etc). Species that rely upon specific thermal regimes may be restricted to particular types of retreat-sites, and hence vulnerable to anthropogenic habitat disturbance. We investigated the role of thermal factors in retreat-site selection by an endangered snake species: the broad-headed snake, Hoplocephalus bungaroides. Broad-headed snakes are restricted to sandstone rock outcrops where exfoliated boulders of different sizes and thicknesses provide a suite of retreat-sites with unique thermal characteristics. Body temperatures of snakes sheltering under rocks are determined by the degree of shading and the thickness of the rock. In the laboratory, broad-headed snakes select temperatures around 30°C, and strike speed is maximised at this temperature. From these data, we predicted seasonal patterns of habitat use by the snakes, by assuming that snakes would select retreat-sites with temperatures within their `preferred' body temperature range. Radiotelemetric monitoring of 25 adult snakes (total of 33 snake-seasons of data) and mark–recapture data from 96 tagged snakes (including 56 juveniles) supported our predictions. During spring, snakes actively selected thin (≤15 cm thick) unshaded rocks. These `hot' rocks allowed snakes to attain body temperatures within their set-point range for long periods of time. The snakes rarely moved between rocks, and a small number of rocks received frequent use by snakes of all sizes. Telemetered snakes also used cliff-top crevices exposed to the afternoon sun (i.e. with north or westerly aspects) and avoided cooler crevices (those with easterly and southerly aspects). During summer, snakes avoided thin exposed rocks which became too hot for them to tolerate (often, >40°C). Although some snakes moved to thicker and more shaded rocks, most snakes abandoned the rock outcrops and moved into adjacent woodland. The seasonal timing of this habitat shift varied among years, but coincided with the onset of hot weather. Thus, simple measurements of the thermal characteristics of snake retreat-sites allowed us to successfully predict major patterns of habitat use, and provide a basis from which to plan the protection and/or restoration of critical habitat components for this endangered species.

The ductility reduction factor in the seismic design of buildings

This paper presents new trends in the relationship between the ductility reduction factor and the ductility demand in the seismic design of buildings. A total of 4860 inelastic time-history analyses were carried out to study this relationship using 60 single-degree-of-freedom models excited by an ensemble of 81 earthquake accelerogram records from around the world. The asymmetrical distribution of the results highlighted the inaccuracies associated with assuming a normal distribution simply described by the mean and standard deviation to represent the data. A probability of exceedence approach has been used based on counting the number of occurrences the ductility demand exceeds a specified level. The ductility reduction factors developed in this study are consistent with other studies in the long-period range but are different in the short-period range. The ductility reduction factor for very short period buildings of limited ductility has been found to be greater than previously predicted. © 1998 John Wiley & Sons, Ltd.

Extension of probability-consistent response spectra in long-period range (in Chinese): Tao Nengfu, Zhang Zaiyong & Li Wenyi, Earthquake Engineering & Engineering Vibration, 15(2), 1995, pp 19–28

Extension of probability-consistent response spectra in long-period range (in Chinese): Tao Nengfu, Zhang Zaiyong & Li Wenyi, Earthquake Engineering & Engineering Vibration, 15(2), 1995, pp 19–28

On the detectability of a highly conductive layer in the upper mantle beneath the Black Forest crystalline using magnetotelluric methods

SUMMARY Simultaneous geomagnetic and telluric variations (600 s-4 hr) were observed at two stations on the Rhine-Graben sediments and on the neighbouring Black Forest crystalline in order to extend the pulsation observations (10-600 s) of former magnetotelluric (MT) surveys to longer periods. These observations completely describe the anomalous magnetic and telluric fields in terms of a set of transfer functions using the Black Forest station as 'normal'. In the period range from 30 s to 4 hr the horizontal and vertical magnetic transfer functions of the Rhine-Graben anomaly are characterized by continuously decreasing amplitudes. The local Schmucker induction arrows point uniformly 45 south-east for all long-period geomagnetic transfer functions, and the NW-SE-striking direction in the upper mantle derived from the induction arrows is also consistent with the preferred telluric direction in the Black Forest. In both areas large offsets of apparent resistivity and phase curves for the E- and B-polarization directions are observed, except that the phase curves converge above 400s in the long-period range. The interpretation of the period dependences of the observed magnetic and telluric transfer functions from 600 s to 4 hr by a 2-D conductivity model requires a highly conductive layer in the upper mantle at a depth of 120 km beneath the Black Forest. This confirms Bahr's (1992) model for a highly conductive layer in the upper mantle that has also been found south of the Alps (Braitenberg et al. 1994) and which is interrupted by low conductive alpine roots. However, no information about such a layer beneath the Rhine Graben can be derived. 2-D model studies have shown that an improved depth resolution of highly conductive layers in the upper mantle is possible using telluric phases, but the transfer functions for the vertical magnetic fields are not sensitive enough for the determination of the depth of an upper mantle conductive layer.

Design and implementation of a fibre-optic-based residual chlorine monitor

The design and implementation of a prototype optical residual chlorine monitor (RCM) for the purpose of chlorine concentration measurement in continuous flow is reported. A precision of 0.1 mg/l measured as OCl − is reported and the upper limit of the measurement range can be extended from 1 to 20 mg/l with a change in concentration of an added reagent. A background reference to allow for the presence of other interfering species is obtained by taking the ratio of the signals measured before and after chlorine is removed from the sample, with the addition of sodium sulphite. This compensates for any lamp and electronic-circuit drifts. The prototype has been tested over a wider range of waters and long periods of up to 24 h.

Long-period microseisms at Umeå, Sweden

Microseisms in the period range 14–20 s recorded by the long-period Press-Ewing seismographs at Umeå (63°48.9′N, 20°14.2′E) are investigated with special regard to their properties and their origin. In the 11-year period (1964–1974) under investigation, 28 clear long-period microseismic storms were detected by visual inspection of Umeå records. With an annual average of 2–3 cases, these represent the best developed storms. However, it is very likely that additional weaker storms could be detected by higher instrument magnification in the long-period range or by record filtering. Among the stations in our seismograph network, Uppsala and Kiruna also operate long-period seismographs, but they are of lower magnification than at Umeå. In fact, it is too low to permit visual detection of long-period microseismic storms, except very rarely at Uppsala.

Distortions in long-period geomagnetic variations owing to deep electrical inhomogeneities

The effect produced by a sharp discontinuity in the upper boundary of the conductosphere is analysed in order to evaluate the distortions introduced in geomagnetic variation profiles in the long-period range of the spectra. To do so, a conformal mapping method is applied and the results are compared with the ones obtained in the case of lateral homogeneity. This model is also applied to interpret the internal part of the geomagnetic daily variations at the equatorial zones of Peru and central Africa.

地震波の発生伝播理論を考慮した模擬地震動作成法

There are two kinds of the method for predicting strong ground motions. One is the method based on the fault model, which has been developed by seismologists to simuate earthquake motions deterministically in the longer period range. The other method has been developed by earthquake engineers to calculate earthquake motions stochastically in the shorter period range. The engineering method usually consists of amplitude spectrum, envelope function, and duration time of strong ground motions. They are usually estimated under the regression analysis for the empirical relations to earthquake magnitude and hypocentral distance. In the present study, the engineering method is improved on the basis of the theories of seismic-wave radiation and propagation. The new method is applied to simulate accelerograms observed at 3 stations for the 1978 off Miyagi prefecture earthquake (M = 7.4). The characteristics of all the accelerograms, e. g. the effect of rupture propagation on the fault plane, can be expressed by the simulated waves in the frequency range higher than 1 Hz, though the three stations are located at the different distances and directions from the earthquake fault. These results suggest that the new method is applicable for predicting strong ground motions of large earthquakes.

Observed baroclinic Energy Conversions in Wavenumbers Domain for Three Winters: A Time Series Analysis

Abstract Daily European Centre for Medium Weather Forecasting (ECMWF) analyses (Reading, GB) for three winters were used to compute the two baroclinic energy transformations C(AgAm) (related to νmTmλ and zonal wavenumber m) and C(AmKm) (related to ωmTmλ and m) averaged over a latitudinal belt north of 45°N and over the troposphere up to 300 mb. The main aim of this paper is to discuss the scalewise statistical interdependence between these conversions as part of baroclinic activity (Ag→Am→Km). Additionally we consider the influence of eddy energy on baroclinic activity of single waves. By a simplified form of the ω-equation it is demonstrated that the correlation between the two baroclinic conversions C(AgAm) and C(AmKm) should increase from small to large m. Cross-spectral analyses of the two time series of C(AzAm) and C(AmKm) reveal that for large scales, e.g., m = 2,3, significant coherency is concentrated in the longer period range. As for the so-called waves (m > 5) the coherency is distributed almos...

Design, Construction and Characterization of a Low-Cost High-Precision Digital Integrator

ABSTRACT A low cost, high precision electronic integrator allowing accurate integration of analog input signals over a wide dynamic signal range for long and short integration periods is described. The utility of this integrator is demonstrated in the controlled potential reduction of Pb++ where the i - t curve is represented by the number of coulombs accumulated and displayed in digital form. With this value and application of Faraday's Law, the n value of the electrode reaction is calculated. The obtained n value of 1.95 shows good agreement with the expected value of 2.00.

Observation of 1- to 5-second microtremors and their application to earthquake engineering. Part II. Evaluation of site effect upon seismic wave amplification due to extremely deep soil deposits

abstractThe usefulness of long-period microtremor observation for earthquake engineering problems at extremely deep soil deposit site was examined in this study. Microtremor observations were made in the Niigata Plain, Japan, and in Los Angeles, California, where depths to the basement rock are several kilometers. These two locations were selected because strong-motion records obtained during the Niigata earthquake of 1964 and the San Fernando earthquake of 1971 contain large long-period amplitudes. Understanding why these predominate long-period motions were recorded is important for the evaluation of seismic input motions for large-scale structures.Long-period microtremor observations were carried out in both areas in order to evaluate the characteristics of deep soil. Observations were performed simultaneously at a number of stations to distinguish the nature of deep soil deposit. The result of Fourier analysis showed that amplitude of microtremors in long-period range increases systematically from the point of basement rock outcrop to deep deposit site, with the increase corresponding to the depth-to-basement rock. This relationship coincides with that observed in the strong-motion earthquake records. These analyses indicated that simultaneous observation of long-period microtremors at a number of stations can provide insight to the characteristic of deep soil amplification and, therefore, permit estimation of seismic input motions for large-scale structures.