Use of whole body vibration in individuals with chronic stroke: Transmissibility and signal purity

This study examined (1) the influence of whole body vibration (WBV) frequency (20 Hz, 30 Hz, 40 Hz), amplitude (low: 0.8 mm and high: 1.5 mm) and body postures (high-squat, deep-squat, tip-toe standing) on WBV transmissibility and signal purity, and (2) the relationship between stroke motor impairment and WBV transmissibility/signal purity. Thirty-four participants with chronic stroke were tested under 18 different conditions with unique combinations of WBV frequency, amplitude, and body posture. Lower limb motor function and muscle spasticity were assessed using the Fugl-Meyer Assessment and Modified Ashworth Scale respectively. Nine tri-axial accelerometers were used to measure acceleration at the WBV platform, and the head, third lumbar vertebra, and bilateral hips, knees, and ankles. The results indicated that WBV amplitude, frequency, body postures and their interactions significantly influenced the vibration transmissibility and signal purity among people with chronic stroke. In all anatomical landmarks except the ankle, the transmissibility decreased with increased frequency, increased amplitude or increased knee flexion angle. The transmissibility was similar between the paretic and non-paretic side, except at the ankle during tip-toe standing. Less severe lower limb motor impairment was associated with greater transmissibility at the paretic ankle, knee and hip in certain WBV conditions. Leg muscle spasticity was not significantly related to WBV transmissibility. In clinical practice, WBV amplitude, frequency, body postures need to be considered regarding the therapeutic purpose. Good contact between the feet and vibration platform and symmetrical body-weight distribution pattern should be ensured.     

Dynamic forces over the interface between a seated human body and a rigid seat during vertical whole-body vibration

Biodynamic responses of the seated human body are usually measured and modelled assuming a single point of vibration excitation. With vertical vibration excitation, this study investigated how forces are distributed over the body-seat interface. Vertical and fore-and-aft forces were measured beneath the ischial tuberosities, middle thighs, and front thighs of 14 subjects sitting on a rigid flat seat in three postures with different thigh contact while exposed to random vertical vibration at three magnitudes. Measures of apparent mass were calculated from transfer functions between the vertical acceleration of the seat and the vertical or fore-and-aft forces measured at the three locations, and the sum of these forces. When sitting normally or sitting with a high footrest, vertical forces at the ischial tuberosities dominated the vertical apparent mass. With feet unsupported to give increased thigh contact, vertical forces at the front thighs were dominant around 8 Hz. Around 3–7 Hz, fore-and-aft forces at the middle thighs dominated the fore-and-aft cross-axis apparent mass. Around 8–10 Hz, fore-and-aft forces were dominant at the ischial tuberosities with feet supported but at the front thighs with feet unsupported. All apparent masses were nonlinear: as the vibration magnitude increased the resonance frequencies decreased. With feet unsupported, the nonlinearity in the apparent mass was greater at the front thighs than at the ischial tuberosities. It is concluded that when the thighs are supported on a seat it is not appropriate to assume the body has a single point of vibration excitation.     

Specific absorption rate and electric field measurements in the near field of six mobile phone base station antennas

In this article, the exposure to radio frequency electromagnetic fields was studied in close proximity (distances of 10, 100, 300, and 600 mm) to six base station antennas. The specific absorption rate (SAR) in 800 mm × 500 mm × 200 mm box phantom as well as unperturbed electric field (E) in air was measured. The results were used to determine whether the measurement of local maximum of unperturbed electric field can be used as a compliance check for local exposure. Also, the conservativeness of this assessment method compared to the ICNIRP basic restriction was studied. Moreover, the assessment of whole‐body exposure was discussed and the distance ranges presented in which the ICNIRP limit for local exposure could be exceeded before the limit for whole‐body SAR. These results show that the electric field measurement alone can be used for easy compliance check for the local exposure at all distances and for all antenna types studied. However, in some cases when the local peak value of E was compared directly to the ICNIRP reference level for unperturbed E, the exposure was overestimated only very slightly (by factor 1.1) compared to the basic restriction for localized SAR in a human, and hence these results can not be generalized to all antenna types. Moreover, it was shown that the limit for localized exposure could be exceeded before the limit for the whole‐body average SAR, if the distance to the antenna was less than 240 mm. Bioelectromagnetics 30:307–312, 2009. © 2009 Wiley‐Liss, Inc.     

Pulsed Electromagnetic Field Versus Whole Body Vibration on Cartilage and Subchondral Trabecular Bone in Mice With Knee Osteoarthritis

Pulsed electromagnetic field (PEMF) and whole body vibration (WBV) interventions are expected to be important strategies for management of osteoarthritis (OA). The aim of the study was to investigate the comparative effectiveness of PEMF versus WBV on cartilage and subchondral trabecular bone in mice with knee OA (KOA) induced by surgical destabilization of the medial meniscus (DMM). Forty 12-week-old male C57/BL mice were randomly divided into four groups (n = 10): Control, OA, PEMF, and WBV. OA was induced (OA, PEMF, and WBV groups) by surgical DMM of right knee joint. Mice in PEMF group received 1 h/day PEMF exposure with 75 Hz, 1.6 mT for 4 weeks, and the WBV group was exposed to WBV for 20 min/day with 5 Hz, 4 mm, 0.3 g peak acceleration for 4 weeks. Micro-computed tomography (micro-CT), histology, and immunohistochemistry analyses were performed to evaluate the changes in cartilage and microstructure of trabecular bone. The bone volume fraction (BV/TV), trabecular thickness (Tb.Th), and trabecular number (Tb.N) increased, and bone surface/bone volume (BS/BV) decreased by micro-CT analysis in PEMF and WBV groups. The Osteoarthritis Research Society International (OARSI) scores in PEMF and WBV groups were significantly lower than in the OA group. Immunohistochemical results showed that PEMF and WBV promoted expressions of Aggrecan, and inhibited expressions of IL-1β, ADAMTS4, and MMP13. Superior results are seen in PEMF group compared with WBV group. Both PEMF and WBV were effective, could delay cartilage degeneration and preserve subchondral trabecular bone microarchitecture, and PEMF was found to be superior to WBV. Bioelectromagnetics. 2020;41:298–307 © 2020 Bioelectromagnetics Society     

Between‐country comparison of whole‐body SAR from personal exposure data in Urban areas

In five countries (Belgium, Switzerland, Slovenia, Hungary, and the Netherlands), personal radio frequency electromagnetic field measurements were performed in different microenvironments such as homes, public transports, or outdoors using the same exposure meters. From the mean personal field exposure levels (excluding mobile phone exposure), whole‐body absorption values in a 1‐year‐old child and adult male model were calculated using a statistical multipath exposure method and compared for the five countries. All mean absorptions (maximal total absorption of 3.4 µW/kg for the child and 1.8 µW/kg for the adult) were well below the International Commission on Non‐Ionizing Radiation Protection (ICNIRP) basic restriction of 0.08 W/kg for the general public. Generally, incident field exposure levels were well correlated with whole‐body absorptions (SAR_wb), although the type of microenvironment, frequency of the signals, and dimensions of the considered phantom modify the relationship between these exposure measures. Exposure to the television and Digital Audio Broadcasting band caused relatively higher SAR_wb values (up to 65%) for the 1‐year‐old child than signals at higher frequencies due to the body size‐dependent absorption rates. Frequency Modulation (FM) caused relatively higher absorptions (up to 80%) in the adult male. Bioelectromagnetics 33:682–694, 2012. © 2012 Wiley Periodicals, Inc.     

不同坡位水曲柳木质部解剖特征及其与气候关系

随着气候变暖,东北地区暖干化加剧。为了解干旱胁迫对小兴安岭地区不同坡位水曲柳径向生长的影响,采用木材解剖学方法,分析了水曲柳木质部解剖特征对不同坡位水分变化的响应。结果表明: 上、下坡位水曲柳木质部解剖参数整体上变化趋势一致,导管数量呈线性分布,最大导管面积和总导管面积总体上呈对数分布,平均导管面积总体上呈偏正态分布。不同坡位多个解剖参数均存在显著差异,下坡位导管数量、导管面积总体上大于上坡位。大部分解剖参数与日积温呈显著正相关,但存在一定差异,上坡位水曲柳总导管面积与日均温呈正相关,导管数量、总导管面积与相对湿度呈正相关,相关性均大于下坡位。上坡位最小导管面积与日积温和相对湿度呈显著负相关;而下坡位,总导管面积与相对湿度呈显著正相关。气候暖干化会导致水曲柳导管面积和导管数量相对减少,但基本上不影响导管分布状况,上、下坡位导管分布基本一致。目前,气候暖干化未限制而是促进了水曲柳的径向生长。     

Current density in a model of a human body with a conductive implant exposed to ELF electric and magnetic fields

A numerical model of a human body with an intramedullary nail in the femur was built to evaluate the effects of the implant on the current density distribution in extremely low frequency electric and magnetic fields. The intramedullary nail was chosen because it is one of the longest high conductive implants used in the human body. As such it is expected to alter the electric and magnetic fields significantly. The exposure was a simultaneous combination of inferior to superior electric field and posterior to anterior magnetic field both alternating at 50 Hz with the values corresponding to the ICNIRP reference levels: 5000 V m^?1 for electric field and 100 µT for magnetic flux density. The calculated current density distribution inside the model was compared to the ICNIRP basic restrictions for general public (2 mA m^?2). The results show that the implant significantly increases the current density up to 9.5 mA m^?2 in the region where it is in contact with soft tissue in the model with the implant in comparison to 0.9 mA m^?2 in the model without the implant. As demonstrated the ICNIRP basic restrictions are exceeded in a limited volume of the tissue in spite of the compliance with the ICNIRP reference levels for general public, meaning that the existing safety limits do not necessarily protect implanted persons to the same extent as they protect people without implants. Bioelectromagnetics 30:591–599, 2009. © 2009 Wiley‐Liss, Inc.     

Personal exposure to mobile phone frequencies and well-being in adults: a cross-sectional study based on dosimetry

The use of mobile phone telecommunication has increased in recent years. In parallel, there is growing concern about possible adverse health effects of cellular phone networks. We used personal dosimetry to investigate the association between exposure to mobile phone frequencies and well-being in adults. A random population-based sample of 329 adults living in four different Bavarian towns was assembled for the study. Using a dosimeter (ESM-140 Maschek Electronics), we obtained an exposure profile over 24 h for three mobile phone frequency ranges (measurement interval 1 s, limit of determination 0.05 V/m). Exposure levels over waking hours were totalled and expressed as mean percentage of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) reference level. Each participant reported acute symptoms in a day-long diary. Data on five groups of chronic symptoms and potential confounders were assessed during an interview. The overall exposure to high-frequency electromagnetic fields was markedly below the ICNIRP reference level. We did not find any statistically significant association between the exposure and chronic symptoms or between the exposure and acute symptoms. Larger studies using mobile phone dosimetry are warranted to confirm these findings.     

Vibration stimuli and the differentiation of musculoskeletal progenitor cells: Review of results in vitro and in vivo

Due to the increasing burden on healthcare budgets of musculoskeletal system disease and injury, there is a growing need for safe, effective and simple therapies. Conditions such as osteoporosis severely impact onquality of life and result in hundreds of hours of hospital time and resources. There is growing interest in the use of low magnitude, high frequency vibration(LMHFV) to improve bone structure and muscle performance in a variety of different patient groups. The technique has shown promise in a number of different diseases, but is poorly understood in terms of the mechanism of action. Scientific papers concerning both the in vivo and in vitro use of LMHFV are growing fast, but they cover a wide range of study types, outcomes measured and regimens tested. This paper aims to provide an overview of some effects of LMHFV found during in vivo studies. Furthermore we will review research concerning the effects of vibration on the cellular responses, in particular for cells within the musculoskeletal system. This includes both osteogenesis and adipogenesis, as well as the interaction between MSCs and other cell types within bone tissue.     

Statistical multi‐path exposure method for assessing the whole‐body SAR in a heterogeneous human body model in a realistic environment

Assessing the whole‐body absorption in a human in a realistic environment requires a statistical approach covering all possible exposure situations. This article describes the development of a statistical multi‐path exposure method for heterogeneous realistic human body models. The method is applied for the 6‐year‐old Virtual Family boy (VFB) exposed to the GSM downlink at 950 MHz. It is shown that the whole‐body SAR does not differ significantly over the different environments at an operating frequency of 950 MHz. Furthermore, the whole‐body SAR in the VFB for multi‐path exposure exceeds the whole‐body SAR for worst‐case single‐incident plane wave exposure by 3.6%. Moreover, the ICNIRP reference levels are not conservative with the basic restrictions in 0.3% of the exposure samples for the VFB at the GSM downlink of 950 MHz. The homogeneous spheroid with the dielectric properties of the head suggested by the IEC underestimates the absorption compared to realistic human body models. Moreover, the variation in the whole‐body SAR for realistic human body models is larger than for homogeneous spheroid models. This is mainly due to the heterogeneity of the tissues and the irregular shape of the realistic human body model compared to homogeneous spheroid human body models. Bioelectromagnetics 34:240–251, 2013. © 2012 Wiley Periodicals, Inc.     

Exposure assessment in front of a multi-band base station antenna

This study investigates occupational exposure to electromagnetic fields in front of a multi‐band base station antenna for mobile communications at 900, 1800, and 2100 MHz. Finite‐difference time‐domain method was used to first validate the antenna model against measurement results published in the literature and then investigate the specific absorption rate (SAR) in two heterogeneous, anatomically correct human models (Virtual Family male and female) at distances from 10 to 1000 mm. Special attention was given to simultaneous exposure to fields of three different frequencies, their interaction and the additivity of SAR resulting from each frequency. The results show that the highest frequency—2100 MHz—results in the highest spatial‐peak SAR averaged over 10 g of tissue, while the whole‐body SAR is similar at all three frequencies. At distances >200 mm from the antenna, the whole‐body SAR is a more limiting factor for compliance to exposure guidelines, while at shorter distances the spatial‐peak SAR may be more limiting. For the evaluation of combined exposure, a simple summation of spatial‐peak SAR maxima at each frequency gives a good estimation for combined exposure, which was also found to depend on the distribution of transmitting power between the different frequency bands. Bioelectromagnetics 32:234–242, 2011. © 2010 Wiley‐Liss, Inc.     

The acute effects of different training loads of whole body vibration on flexibility and explosive strength of lower limbs in divers

The purpose of this study was to examine the acute effects of different vibration loads (frequency and amplitude) of whole-body vibration (WBV) on flexibility and explosive strength of lower limbs in springboard divers. Eighteen male and female divers, aged 19 ± 2 years, volunteered to perform 3 different WBV protocols in the present study. To assess the vibration effect, flexibility and explosive strength of lower limbs were measured before (Pre), immediately after (Post 1) and 15 min after the end of vibration exposure (Post 15). Three protocols with different frequencies and amplitudes were used in the present study: a) low vibration frequency and amplitude (30 Hz/2 mm); b) high vibration frequency and amplitude (50 Hz/4 mm); c) a control protocol (no vibration). WBV protocols were performed on a Power Plate platform, whereas the no vibration divers performed the same protocol but with the vibration platform turned off. A two-way ANOVA 3 x 3 (protocol × time) with repeated measures on both factors was used. The level of significance was set at p < 0.05. Univariate analyses with simple contrasts across time were selected as post hoc tests. Intraclass coefficients (ICC) were used to assess the reliability across time. The results indicated that flexibility and explosive strength of lower limbs were significantly higher in both WBV protocols compared to the no vibration group (NVG). The greatest improvement in flexibility and explosive strength, which occurred immediately after vibration treatment, was maintained 15 min later in both WBV protocols, whereas NVG revealed a significant decrease 15 min later, in all examined strength parameters. In conclusion, a bout of WBV significantly increased flexibility and explosive strength in competitive divers compared with the NVG. Therefore, it is recommended to incorporate WBV as a method to increase flexibility and vertical jump height in sports where these parameters play an important role in the success outcome of these sports.     

Effects of parental body condition and size on reproductive success in a tenebrionid beetle with biparental care

Abstract. 1. The beetle Parastizopus armaticeps (Coleoptera: Tenebrionidae) inhabits the Kalahari desert of southern Africa, constructs breeding burrows after rainfall, and shows extensive biparental care. Previous work has shown that it is predominantly male size, not female size, that determines breeding success; however, in the field these beetles show size assortative mating. This might obscure or override effects of female size on reproduction. Moreover, the inaccessibility of the breeding burrows makes it impossible to test effects of female and male size on offspring development and survival before adulthood. 2. To disentangle the effects of male and female length, body mass, and body condition on reproductive success, males and females were paired randomly in small breeding cages in the laboratory (n = 887 breeding pairs). The construction of the breeding cages allowed a clear view of the brood chamber contents at each stage in offspring development. Larva, pupa, and imago numbers and development were monitored daily, and imago mass at hatching from the pupa (hatchlings), offspring mass, and offspring body length at complete exoskeleton melanisation (juveniles) were determined. 3. There was a weak positive correlation between body condition and body length for females only. Breeding chronology was related to male body condition: males in better condition were fast to start and finish a breeding bout. Males in better condition produced heavier hatchlings and juveniles, and larger‐sized males produced larger‐sized juveniles. In contrast, numbers of larvae and juveniles produced were determined mainly by female length and body condition: larger females in better condition hatched more larvae and produced more offspring. 4. The results suggest that male size and condition will be the most important determinant of reproductive success under relatively dry conditions, when burrow length is critical for reproductive success. Female size might be more important for the pair's reproductive success under wet breeding conditions, when burrow length is less critical for successful reproduction.     

X线全身照射对2型糖尿病KKAy小鼠造血免疫系统功能的影响

目的观察X线全身照射对2型糖尿病模型KKAy小鼠的造血免疫系统功能的损伤作用,并与对照C57小鼠进行比较。方法KKAy小鼠,分为对照组和照射组,照射组小鼠经X线全身照射,剂量4Gy,C57小鼠作为对照。照射后15d检测小鼠的外周血常规,流式细胞术检测骨髓中造血祖细胞、造血干细胞和长期造血干细胞的比例,脾中B细胞和T细胞的比例,胸腺中CD4CD8双阳性T细胞、CD4单阳性T细胞和CD8单阳性T细胞的比例。通过粒细胞集落形成能力实验评价小鼠造血祖细胞的功能。结果照射前KKAy小鼠的HSC和LT-HSC的比例低于C57小鼠。4Gy全身照射后,KKAy小鼠的外周血WBC、RBC、PLT、HGB和LYM%分别下降了68.42%、12.17%、8.78%、30.12%、70.84%;骨髓中HPC、HSC和LT-HSC的比例分别下降了34.02%、29.49%、35.74%;脾B细胞和T细胞的比例分别下降了57.85%、58.81%;胸腺CD4CD8双阳性细胞的比例下降了51.70%。KKAy小鼠的骨髓HSC、LT-HSC、外周血RBC和HGB的降低幅度显著低于C57小鼠。结论4Gy全身照射损伤KKAy小鼠的造血免疫系统功能,KKAy小鼠可能比C57小鼠表现出对电离辐射较强的耐受性。     

Seasonal variations in copepod body length: a comparison between different species in the Lagoon of Venice

The seasonal variation in length of the most abundant copepod species in the lagoon of Venice were compared and the relative influence of temperature, chlorophyll concentration and salinity examined. Temperature seems to be the primary factor influencing copepod body length in the lagoon of Venice, but the different species vary markedly in their response. Calanoid copepods (Acartia clausi, A. tonsa, Paracalanus parvus and Centropages ponticus) showed a more definite trend of size variation with temperature than the cyclopoids (Oithona nana and O. similis) and the harpacticoid Euterpina acutifrons. The size of the poecilostomatoids Oncaea media and O. subtilis was not affected by temperature, and was almost constant over time. Differences in the metabolic rates, longevity and specialization of calanoid, cyclopoid and harpacticoid copepods could explain their different responses to temperature.     

不同氮磷比条件下浮游藻类群落变化

选取天津市小型人工湖湖水样品,调整氮磷起始质量比(分别为0.5∶1、7.2∶1、25∶1、50∶1),在水族试验箱内进行生态模拟试验,探讨城市湖水浮游藻类群落对不同氮磷比例的响应.与对照组相比,高氮磷比组绿藻种类减少,蓝藻种类变化不大;低氮磷比组蓝、绿藻种类数均减少.高氮磷比的中氮和高氮箱内,藻类生物量、细胞密度与叶绿素a都远高于对照和高磷箱;高氮箱中叶绿素a均值最高,为69.7 μg·L^-1,中氮箱次之,为54.3 μg·L^-1,对照与高磷箱分别为30.3和29.7 μg·L^-1.试验中后期,高磷箱绿藻门美丽胶网藻(Dictyosphaerium pulchellum)一直占据优势地位;而中氮箱和高氮箱主要优势藻种为皮状席藻(Phormidium corium)、细胶鞘藻(Phormidium tenue)、湖泊鞘丝藻(Lyngbya limnetica)和铜绿微囊藻(Microcystis aeruginosa)等蓝藻.对照箱内物种丰富度最高,中氮箱内生态优势度最高.     

Repellency of inseminated Culex pipiens (Diptera: Culicidae) females to various wing-beat sound frequencies in modulated intensities in a flight chamber

Wing‐beat sound frequencies at 370, 440, 493 and 554 Hz were evaluated for female mosquito repellency. One hundred inseminated females of Culex pipiens were introduced into a 30 cm × 30 cm × 3 m screened cage with an electronic device (cellular phone) emitting selected frequencies positioned at one end of the chamber. The mosquitoes were counted in areas of 0.0–0.5, 0.5–1.0, 1.0–2.0 and 2.0–3.0 m from the cellular phone. In a second test, 50 Cx. pipiens were released in the screened cage with a shaved rat as bait placed beside the cellular phone (370 Hz) at the center of the chamber. Statistical analysis (anova ) showed that significantly fewer (P < 0.05) mosquitoes rested near the cellular phone at 370 Hz, but not at the other frequencies. Similarly, there was significant reduction (mean 33.0%) in the number of mosquitoes taking a blood meal on the shaved rat when the cellular phone was turned on (P < 0.01).     

不同频率的电针对大鼠神经源性痛的治疗作用

目的：探讨不同频率的电针能否减轻大鼠神经源性痛。方法：将大鼠右侧L5／L6脊神经结扎,用引起50％抬足的机械刺激阈值评价机械性痛觉超敏,用大鼠5min内从5℃冷权上的抬足次数反映冷诱发的持续性疼痛。用韩氏穴位神经刺激仪给与2Hz或100Hz电刺激。结果：①2Hz和100Hz电针均一轻痛觉超敏,2Hz起效较早。②两种频率电针均能减轻冷诱发的持续性疼痛,但2Hz持续的时间长,多次电针后2Hz的镇痛效果可持续长达48h。③针刺而不通电也能显著减轻冷诱发的持续性痛。结论：电针能减轻神经源性痛,且低频（2Hz）电针的镇痛效果优于高频（100Hz）电针。