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排序方式: 共有86条查询结果,搜索用时 93 毫秒
31.
J. J. M. Cuppen G. F. Wiegertjes H. W. J. Lobee H. F. J. Savelkoul M. A. Elmusharaf A. C. Beynen H. N. A. Grooten W. Smink 《The Environmentalist》2007,27(4):577-583
A hypothesis is proposed how Low Frequency Electromagnetic Field (LF EMF) exposure can stimulate an immune response, based
on recent insights in immunology. We hypothesize that the Immunent EMF treatment induces mild stress to cells, which then
produce cytokines that function as alarms or so called danger signals for the immune system. In this way EMF treatment takes
the place of multiplying pathogens, and the damage these cause, in the triggering of an immune response. In a first series
of experiments in␣vitro common carp head kidney-derived phagocytes were used to determine ROS production as a measure for
immune activation. Exposure to LF EMF signals (200–5,000 Hz) at 5 μT or 1.5 mT led to 42 or 33% increase in immune activity,
respectively, compared to negative control values. EMF could also additionally stimulate chemically pre-stimulated samples
up to 18% (5 μT) or 22% (1.5 mT). Significance of increase in ROS production in the total series was: p < 0.0001. In a second series of experiments in␣vitro commercial goldfish were used. Groups of fish were housed under equal
conditions in at least four control tanks and 8–16 EMF-exposed tanks. Exposure was done with a predominantly vertical field
at field strengths (rms) between 0.15 and 50 μT. Without treatment mortality was about 50% after 18 days, while the treatment
at 5 μT reduced it to 20% on average. At field strengths 0.15, 0.5, 1.5, 5, 15 and 50 μT an equally strong effect was found.
Reducing the field strength to 0.05, 0.06, 0.01 and 0.003 μT showed a gradually decreasing effect, which only at 0.003 μT
is no longer statistically significant. Finally, in␣vitro experiments were done with 560 commercial broiler chickens exposed
to infection pressure from coccidiosis. EMF exposure at 6.5 μT reduced intestinal lesions by 40% and improved feed conversion
by 8%. 相似文献
32.
Comprehensive monitoring technique based on electromagnetic radiation and its applications to mine pressure 总被引:2,自引:0,他引:2
Strata pressures are common potential troubles during coal mining, serious ones can cause great catastrophe. This paper presents a new comprehensive electromagnetic radiation (EMR) monitoring technique to monitor and predict these disasters. In this paper, we studied the relationship of EMR emitted by various, uniaxially loaded, coal rock samples (coal, rock, roof-coal-floor composite) in their whole deformation and failure processes to the applied loads, and found that EMR signal is linearly related to the applied loads, while the number of EMR pulses is a third power function of the applied loads. Therefore, EMR signal is capable of reflecting the stress (load) state, deformation and fracture strength, and internal stress state of coal rock mass. Based on the above, we proposed three methods for measuring rock pressure distribution, periodic pressure, and internal stress distribution of coal rock mass on working faces, and conducted field measurements and verifications. The results showed that (i) EMR has a certain correspondence to support resistance of working faces, and can reflect more accurately the face pressure distribution; (ii) in the mining impacted area located within 100 m in the front of working face, the stress distribution has unimodal and bimodal forms; (iii) EMR signal changes periodically with periodic pressure, and can be used to qualitatively observe and evaluate periodic pressure; (iv) tested with antenna in the borehole into coal rock mass, EMR signal can effectively reflect the internal stress distribution and shifting, which was verified by using traditional drilling cuttings method. In addition, EMR can also be used to check the effect of destress blasting as one of the emergency measures. In conclusion, the results are of practical significance for using EMR to monitor rock pressure and guiding safe underground mining. 相似文献
33.
结合当前我国电磁环境管理的需求,分析了现有电磁环境标准的制定情况及存在的问题,提出以环境质量为核心,构建具有5个不同层次的电磁环境标准体系,包括电磁环境质量标准、电磁辐射排放(控制)标准、电磁环境监测标准、电磁环境基础标准和电磁环境管理技术规范。根据标准的定位、作用、特征及相互关系,提出了电磁环境标准制修订的相关建议。 相似文献
34.
Occupational exposure to radiofrequency (RF) and static magnetic fields at magnetic resonance imaging (MRI) suites is of continuing
concern to personnel who routinely work in this environment. Questions regarding the levels of occupational RF and static
field exposure have increased with the increasing demand for anesthetics to be administered in this environment. The present
study was thus designed towards addressing the above-mentioned problem by gaining information regarding exposure levels of
clinical personnel at MRI units in South Africa. Three 1.5 MRI units in Bloemfontein, South Africa were utilized to evaluate
the exposure of clinical personnel to the electromagnetic fields present in the MRI environment over a period of time and
during different clinical MRI procedures. Three rounds of measurements of RF fields in the MRI environment were done. All
the three measurement rounds were focused on the low frequencies, 5 Hz–32 kHz, as well as on the high frequencies, 300 kHz–40 GHz.
First round measurements were done to establish the background of the RF fields in and around the magnet room during an MRI
examination. Second round RF field measurements were done at a specific location, 1 m away from the bore on the right-hand
side of the bed, in the MRI room. The third round measurements were of the same format as the second round, but the specific
location was against the magnet bore. Two pieces of Narda Safety Test Solution instruments, the EFA-300 and EMR-300, were
used to measure the electromagnetic and magnetic exposure fields generated from the MRI scanners. Results of the measurements
indicate that the electromagnetic fields measured during different clinical procedures do not exceed the International Commission
on Non-Ionizing Radiation Protection (2000) guidelines in these units. Results from round two and three showed that the RF
and gradient exposure 1 m and up against the bore entrance does not exceed these guidelines (rms average over 6 min). Ongoing
new developments in MRI scanning create the need for continuously monitoring exposure of patients and workers to the EMF fields
in the MRI environment. 相似文献
35.
E. Battisti A. Albanese L. Bianciardi A. I. Fiaschi M. Rigato A. Vittoria G. L. Messa N. Giordano 《The Environmentalist》2009,29(2):190-195
The utility and the safety of the extremely low frequencies (ELF) electromagnetic fields in the treatment of numerous diseases
have been demonstrated. Moreover, the effects of these fields seem to depend on their respective codes (frequency, intensity,
waveform). We want to value the effects and the safety of the therapeutic application of a musically modulated electromagnetic
field (TAMMEF) system, which field is piloted by a musical signal and its parameters (frequency, intensity, waveform) are
modified in time, randomly varying within the respective ranges, so that all possible codes can occur during a single application.
Sixty subjects, affected by shoulder periarthritis were enrolled in the study and randomly divided into three groups of 20
patients each: the first exposed to TAMMEF, the second exposed to ELF, the third exposed to a simulated field. All subjects
underwent a cycle of 15 daily sessions of 30 min each and a clinical examination upon enrolment, after 7 days of therapy,
at the end of the cycle and at a follow-up 30 days later. All the patients of TAMMEF group and ELF group completed the therapy
without the appearance of side effects: they presented a significant improvement of the subjective pain and the functional
limitation, which remained stable at the follow-up examination. In those exposed to a simulated field group, there was no
improvement of the pain symptoms or articular functionality. This study suggests that the TAMMEF system is efficacious and
safe in the control of pain symptoms and in the reduction of functional limitation in patients with shoulder periarthritis.
Moreover, the effects of the TAMMEF system cover those produced by the ELF field. 相似文献
36.
Pawel Bienkowski 《The Environmentalist》2009,29(2):130-134
This article presents methods and results of interlaboratory comparison in the electromagnetic field (EMF) survey measurements
performed by Electromagnetic Environment Protection Laboratory. Based on the results, the author analyzed factors affecting
the precision of EMF measurements, in particular—difficult to estimate—the “human factor”. In practice, the human factor has
never been taken into account in the EMF measurements accuracy estimations budget, and the author estimate the importance
of this factor that may include even up to half of the total uncertainty of measurements. Taking into account all factors
depredating the accuracy of measurements, the uncertainty of the survey EMF measurements was estimated at the level of 2–4 dB. 相似文献
37.
卫星地球站电磁环境的影响预测 总被引:2,自引:0,他引:2
对某卫星地球站划定近场,远场后,对近场内最大功率密度,远场轴向功率密度,近场地面功率密度作了预测,对天线轴向前方建筑物高度作了特别考虑,结果表明:近场内最大功率密度为629uw/m2,是GB8702-88《电磁辐射防护规定》职业照射导出限值的1.5倍,远场轴向3400米后,功率密度降到GB8702-88规定的公众照射导出限值的1/5以下;天线对地面的辐射环境影响较小,但轴向前方建筑物必须实行限高保护。 相似文献
38.
广州市区广播电视发射塔电磁辐射调查 总被引:3,自引:1,他引:3
为了解广州市区广东电视发射塔和广州电视发射塔电磁辐射状况,广州市环境监测中心站对电视发射塔周围的环境进行了监测。结果表明.两座电视发射塔周围电磁辐射水平随着距离的增加,呈现下降的趋势;两座广播电视发射塔周围高层建筑敏感点窗外电磁辐射水平随着楼层的增加.呈现上升的趋势。 相似文献
39.
40.
此文对板材电磁成形进行了较全面的实验研究,并对板材在成形过程中变形规律进行了分析,同时对成形效率进行了讨论,为电磁成形技术的推广应用奠定了基础。 相似文献