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1.
Observations were carried out during the Energy Budget Campaign with the aim of measuring keV particle precipitation in the ionosphere over a region covering the rocket range. These measurements are important as particle precipitation constitutes one of the major energy inputs into the ionosphere during an auroral substorm. Estimates of electron precipitation have been made in three different regions of the energy spectrum. Two optical emissions were measured that are proportional to electron precipitation of a few hundred eV and a few keV, respectively, and cosmic noise absorption related to electrons of a few tens of keV. The relative variation between the signals may be interpreted as changes of the energy spectrum of the particles. Measurements from the ground have been compared with satellite measurements to obtain the relation between the two methods. The ground-based observations, which are continuous in time and cover a large area, may be used to separate the spatial and temporal variations and to give the large scale substorm frame of reference for the rocket data. The results may also be used in the interpretation of other measurements on board rockets where a knowledge of the precipitated particles is required.  相似文献   

2.
The problem of the precipitation of keV range protons and neutral hydrogen atoms into the equatorial atmosphere is studied by the Monte-Carlo technique, and the energy deposition is calculated for different atmospheric models corresponding to low, medium and high solar activity conditions. It is found that the total energy deposited is independent of the atmospheric model and is equal to 16% of the incident energy, but the energy deposition profile varies. The dependence of the profile parameters on the neutral atmospheric model is examined in detail. An empirical model of the Chapman type distribution, involving only the neutral atmospheric density, has been developed to represent the energy deposition profile for any solar activity condition.  相似文献   

3.
An analysis of energy use by Neanderthals in Northern Europe during the mild Eem interglacial period is carried out with consideration of the metabolic energy production required for compensating energy losses during sleep, at daily settlement activities and during hunting expeditions, including transport of food from slain animals back to the settlement. Additional energy sources for heat, security and cooking are derived from fireplaces in the open or within shelters such as caves or huts. The analysis leads to insights not available from archaeological findings that are mostly limited to durable items such as those made of stone: Even during the benign Eem period, Neanderthals faced a considerable heat-loss problem. Wearing tailored clothes or some similar measure was necessary for survival. An animal skin across the shoulder would not have sufficed to survive even average cold winter temperatures and body cooling by convection caused by wind. Clothes and particularly footwear had to be sewn together tightly in order to prevent intrusion of water or snow. The analysis of hunting activity evolvement in real time further shows that during summer warmth, transport of meat back to the base settlement would not be possible without some technique to avoid that the meat rots. The only likely technique is meat drying at the killing site, which indicates further skills in Neanderthal societies that have not been identified by other routes of investigation.  相似文献   

4.
Data from EISCAT are used to determine Joule and particle heating rates. As CP3 programs include scans in the meridian plane of Tromsø, some latitudinal extents of these rates are deduced. They are shown for a period of 24 h on 18–19 January 1984.If a linear relationship is assumed between height-integrated Joule heating rates and variations of the horizontal component of the magnetic field at ground level, the corresponding scaling factor depends on a certain ratio of the conductivities. Variations of this ratio versus time and latitude are shown for the same period.  相似文献   

5.
In an earlier paper, we showed that charged aerosols play a crucial role in enhancing radar echoes from the summer polar mesosphere through reduced diffusion turbulent scatter and dressed aerosol scatter (Cho et al., 1992a). Here, we explore the effects of charged aerosols on radar scatter through ‘fossil’ turbulence and electron density depletion layers. We find that the former can produce radar scatter even after the decay of neutral gas turbulence, while the latter, which are probably produced by the scavenging of free electrons by ice particles, are a candidate for causing partial reflection or Fresnel scatter. Furthermore, we examine the mutual aerosol interaction restriction on dressed aerosol scatter more closely. We find that a high ambient electron density and low aerosol number density are needed for effective dressed aerosol scatter to occur. We then show that very small (less than 1 nm radii), negatively charged aerosols enhance electron diffusivity, and thus inhibit radar scatter. Also, ice aerosol sedimentation, in the light of the reduced diffusion theory, leads us to conclude that the statistical peak in Polar Mesospheric Summer Echoes (PMSE) power should be located between the mean mesopause and the average noctilucent cloud (NLC) height, which agrees with observations. Finally, we invoke time lags in the ice particle formation cycle to account for the observed non-correlation between PMSE and NLC occurrence.  相似文献   

6.
Sclerochronology, the study of the skeletal diaries of mollusks and corals, is a high-resolution geochronological tool of versatile usage in archaeology and paleontology with increasingly growing opportunities. Much of the recent efforts have concentrated on building multi-centennial bivalve growth records using annually deposited increments in the Holocene shells, comparable to tree-ring chronologies. In the context of geoarchaeology, the hitherto unachieved potential includes the application of sclerochronology to reconstruct long-term settlement histories. Here we contribute to both of these critical issues by presenting the first multi-shell sclerochronology constrained by methods originally developed in tree-ring research, using anthropogenically deposited bivalve shells of Arctica islandica excavated from a Stone Age midden in North Norway. Our systematic chronological approach to shell growth histories lays the foundation for a multi-dimensional dating framework that interacts between the incremental, radioisotopic and stratigraphic evidence. We show how the crossdating within and between the single-shell records yields a 155-year multi-shell sclerochronology, supported by the 14C AMS dates, that demonstrates minimum midden accumulation of 82 years and a depositional rate of 0.3 cm/yr. Sclerochronology paves the way for radiocarbon wiggle-matching, which narrows the probabilistic 2-σ uncertainty range for the oldest and youngest 14C AMS dates to 3150–2980 and 3060–2890 BC, respectively. We attribute the spectral characteristics of the chronology primarily to the North Atlantic Oscillation, suggesting essentially similar influences of climate variability on the Stone Age culture and our own society.  相似文献   

7.
Abstract

Moral judgements are not easy to make in an age of technological complexity particularly if it is difficult to know all the facts accurately. However, it is possible to state the ethical considerations underlying the global energy problem and to point to possible solutions in the short, medium and long term. The nuclear option is considered in some detail and it is concluded that the procedures of deciding risks should be based on dialogue and mutual education.  相似文献   

8.
During early spring, 1985, the MAE-3 (Middle Atmospheric Electrodynamics) Program was conducted at Poker Flat Research Range, Alaska to study the origin of wintertime mesospheric echoes observed with the Poker Flat MST radar there, by probing the mesosphere with in situ rocket measurements when such echoes occurred. Pre-launch criteria required the appearance of echoes exhibiting some wave structure on the MST radar display; these could be met even under weak precipitation conditions with riometer absorption near or above 1.0 dB. Two morning rockets were launched under such conditions, the first (31.048) on 29 March 1985, at 1703 UT and the second (31.047) on 1 April 1985, at 1657 UT. Both payloads were deployed on a high altitude parachute near a 95 km apogee to provide a stable platform for data acquisition within the mesosphere (below 80 km). Each payload carried a solid state detector to measure energetic electrons between 0.1 and 1.0 MeV and an NaI crystal detector to measure x-rays from >5 to >80 keV. Payload 31.048 also carried a positive ion ‘turbulence’ probe which measured ion density changes (ΔNi/Ni) during payload descent, whereas 31.047 carried a nose tip ‘turbulence’ probe designed to measure electron density changes (ΔNe/Ne) during upleg ram conditions plus a Gerdien condenser for the measurement of bulk ion properties during downleg. The energy deposition curves for each event exhibited peak deposition rates between 75 and 80 km with a half width of 16–18 km, almost exclusively induced by precipitating relativistic electrons. They also showed a maximum bottomside gradient between 65 and 75 km. Radar echoes and atmospheric turbulence were observed in the same altitude domain, consistent with the anticipated need for adequate free thermal electron gradients to make such phenomena visible on the radar. The vertical wave structure from radar echoes was found to be consistent with that observed in horizontal wind and temperature profiles measured by Datasondes flown shortly after each large rocket. An analysis of the wave structure from radar data has shown that although large scale waves (λz ~ 7 km) were found to be present, a higher frequency shorter wavelength (∼ 1–3 km) component probably played a more significant role in modulating the signal-to-noise structure of the radar echoes.  相似文献   

9.
10.
During the October 2004 Australian federal election campaign the expected or possible effect of the election outcome on interest rates was a key point of differentiation between the Australian Labor Party and the Liberal–National Party coalition. The purpose of this paper is twofold. First, we examine whether this effect was a significant factor in the election outcome, as measured by the percentage swing towards the coalition in each electorate. Second, we use standard methodology from financial economics to examine whether the election outcome had an effect on interest rates. Contrary to media coverage of the campaign, we find that the election result did have an effect on interest rates but that the possibility of interest rate changes was not a dominant factor in the election result.  相似文献   

11.
12.
Jennifer Baka 《对极》2017,49(4):977-996
This paper analyzes why and how wasteland development narratives persist through an evaluation of wasteland development policies in India from 1970 to present. Integrating critical scholarship on environmental narratives and enclosures, I find that narratives of wastelands as “empty” spaces available for “improvement” continue because they are metaphors for entrenched struggles between the government's shifting visions of “improvement” and communities whose land use practices contradict these logics. Since the 1970s, “improvement” has meant establishing different types of tree plantations on wastelands to ostensibly provide energy security. These projects have dispossessed land users by enclosing common property lands and by providing forms of energy incommensurate with local needs, a trend I term “energy dispossessions”. Factors enabling energy dispossessions include the government's increased attempts to establish public–private partnerships to carry out “improvement” and a “field of observation” constructed to obscure local livelihoods. Unveiling these logics will help to problematize and contest future iterations of wasteland development.  相似文献   

13.
An artificial layered sandy site was created using a combination of native sand and colored sand (3 parts native uncolored quartz, 1 part colored quartz) in Apalachicola National Forest near Tallahassee, Florida. Twelve layers of sand, each 1 by 1 m in horizontal extent by 10 cm in thickness were emplaced to a depth of 2 m followed by implantation at the surface of a Florida harvester ant (Pogonomymrex badius) colony (the lower two layers were 50 cm thick). The colony excavated a nest, and after 7 months, the sand layers were excavated to the base to test the hypothesis that sand grains were moved upward within the ant nest without reaching the surface. The ants penetrated 11 of the 12 colored layers reaching a depth of 130 cm. Thirty nine sticky-acetate peels of ant chamber floors were collected and colored sand grains were counted under a microscope. More than 16,000 grains were identified in layers that did not originally host them. Of these, more than 80% were unambiguously moved upward. This means that possibly as many as 54,000 upwardly mobile grains were present (ratio of 3:1 uncolored to colored). In relation to optical luminescence (OSL) dating, this means that grains that would not have been optically zeroed by transport to the surface (defined here as subterranean-transported) were present in abundance, and that if the site was ancient, there would have been found many grains that were older than the layers they presently reside in, even if only one colony of harvester ants had disturbed the layers. This is in addition to the fact that backfilling of chambers and tunnels may contribute even more significantly to the presence of a subterranean-transported component of an OSL sample. We conclude that ants can significantly affect the age distributions in sandy archaeological sites. Multiple examples of such disturbances have been documented in the literature. Most relevant to our results are recent studies of the OSL chronology of Pre-Clovis-age and Palaeoindian age archaeological sites in sandy environments in North America that may have been compromised by ant bioturbation of quartz sand grains. Here we have examined in detail the potential effects of one episode of ant nest-building on the age overestimation of affected sediments. From this we found that as few as 12 episodes of bioturbation involving backfilling of chambers in the same volume of sand could lead to the presence of 1 contaminant grain per 50 grains of sample.  相似文献   

14.
作为世界第二和第三的大能源消费国,中国和日本在分散竞争的条件下承受了过多的进口成本。本文在分析能源商品的价格决定因素基础上,探讨中日两国进行能源联合议价的成本与收益。认为这种努力可以在消除能源的亚洲溢价、减少能源竞争成本、促进亚洲能源期货市场发展、增强区域经济联系等方面获得显著收益。同时,联合议价的经济成本比较小,国家安全成本和政治成本则在两国之间存在不对称性,并且难以量化。  相似文献   

15.
This summary serves to introduce the ongoing research and testing of the lichenometric method within the Bothnian region. Within this framework, applications of the Schmidt Test Hammer have also been evaluated. Shore displacement has provided an ideal means for calculating growth and weathering rates. The strength of this study is the combination of independent biologically, geologically and physically based methods in an attempt to solve basic archaeological problems.  相似文献   

16.
Abstract

Sudden changes of state occur at all levels of society, and have always done so, be they marriages ending in divorce, bankruptcies of industrial enterprises, or the collapse of empires. Can such social discontinuities, moving either from order to chaos – the more common event – or from disorder to stability, be compared with perhaps similar events in the natural sciences? Can a valid theory be established to cover the subject of social discontinuities? These questions are addressed after defining the subject, discussing the causes of discontinuities, illustrating various occurrences and stressing the urgency of an analysis of discontinuities, as many assume our present social–technological society is especially prone to collapse. It is concluded that the subject remains a challenge to the social scientist, primarily because the people who are affected by discontinuities constantly change their behaviour and thus affect the phenomenon. This distinguishes the social from the natural sciences.  相似文献   

17.
As an activity‐related pathological lesion, spondylolysis and its prevalence rates are indicative of relative diachronic activity levels in different populations. In this paper we document the prevalence of spondylolytic defects in a series of time‐successive populations with special reference to the recording methods employed, and compare the findings with modern clinical studies. We identify epidemiological trends in expression of the condition through 1500 years in a series of skeletonised human remains from England. This includes a 5th–6th‐century settlement, a 15th‐century mass grave, a 14th to 17th‐century rural parish, a medieval Dominican friary, a medieval leper hospital and an 18th to 19th‐century crypt collection. These skeletal populations sample human groups experiencing considerable social change from an agrarian, non‐centralised early medieval period through the development of the medieval state to the earliest phases of industrialisation in England. A detailed study of all lumbar vertebrae in one of the assemblages highlights discrepancies between clinical prevalence rates for spondylolysis established through radiography, and those resulting from direct osteological analysis of the lumbar region of the vertebral column. Current prevalence rates cited in the osteological as well as the clinical literature are greatly dependent upon the recording methods employed, and the effects of several methods for osteological remains are considered in this treatment. For the populations reported on here, prevalence rates vary from considerably less than 1% to as much as 12%, depending on the method selected. A standardised recording method for spondylolytic lesions is suggested to facilitate accurate prevalence reporting and comparison of activity levels between different populations. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

18.
Richard Newbold Adams. Energy and Structure: A Theory of Social Power. Austin and London: University of Texas Press, 1975. xviii + 353 pp. Figures, tables, references and index. $15.00 cloth, $4.95 paper.  相似文献   

19.
This review summarizes the work in the field of magnetospheric energetic particles during the years 1987–1989. Out of a wealth of contributions it concentrates on a few topics. First it follows the path of ions extracted out of the polar ionosphere and their acceleration parallel and perpendicular to the magnetic field, as well as their subsequent transport into the equatorial magnetosphere and tail region. Then it focuses on acceleration of ions in the magnetotail and the related characteristics in the boundary layers including consequences for current substorm modeling. In the ring current region, the AMPTE and VIKING missions have made possible detailed studies of charge state and pitch-angle distributions as well as their variations during magnetospheric storms and substorms, from which conclusions on the transport and loss processes can be drawn. Recently, observations of energetic particles from orbiting nuclear reactors in the magnetosphere, which can be used as tracers for these satellites, have been made public. However, this may also constitute a serious background problem for future γ-astronomy missions with an increased sensitivity of the instrumentation. Finally, leading beyond the boundaries of the magnetosphere, attention is drawn to the still ongoing debate on the source of energetic particles upstream of the Earth's bow-shock and the respective importance of particle leakage and/or acceleration at the magnetospheric boundaries.  相似文献   

20.
Laboratory experiments have been performed in which the drying rate of discs of paper towelling moistened by water was measured as a function of the strength of the electric field E in which they were placed. The drying rate increased monotonically with E, the associated drying time (in a typical experiment) decreasing by a factor of about 6 as E rose from 0 to 7 kV/cm.  相似文献   

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