Effects of dielectric permittivities on skin heating due to millimeter wave exposure

<p>Abstract</p> <p>Background</p> <p>Because the possibility of millimeter wave (MMW) exposure has increased, public concern about the health issues due to electromagnetic radiation has also increased. While many studies have been conducted for MMW exposure, the effect of dielectric permittivities on skin heating in multilayer/heterogeneous human-body models have not been adequately investigated. This is partly due to the fact that a detailed investigation of skin heating in a multilayer model by computational methods is difficult since many parameters are involved. In the present study, therefore, theoretical analyses were conducted to investigate the relationship between dielectric permittivities and MMW-induced skin heating in a one-dimensional three-layer model (skin, fat, and muscle).</p> <p>Methods</p> <p>Approximate expressions were derived for the temperature elevation and temperature difference in the skin due to MMW exposure from analytical solutions for the temperature distribution. First, the power absorption distribution was approximated from the analytical solution for a one-layer model (skin only). Then, the analytical expression of the temperature in the three-layer model was simplified on the basis of the proposal in our previous study. By examining the approximate expressions, the dominant term influencing skin heating was clarified to identify the effects of the dielectric permittivities. Finally, the effects of dielectric permittivities were clarified by applying partial differentiation to the derived dominant term.</p> <p>Results</p> <p>Skin heating can be characterized by the parameters associated with the dielectric permittivities, independently of morphological and thermal parameters. With the derived expressions, it was first clarified that skin heating correlates with the total power absorbed in the skin rather than the specific absorption rate (SAR) at the skin surface or the incident power density. Using Debye-type expression we next investigated the effect of frequency dispersion on the complex relative permittivity of tissue. The parametric study on the total power absorbed in the skin showed that skin heating increases as the static permittivity and static conductivity decrease. In addition, the maximum temperature elevation on the body surface was approximately 1.6 times that of the minimum case. This difference is smaller than the difference caused by the thermal and morphological parameters reported in our previous study.</p> <p>Conclusion</p> <p>This paper analytically clarified the effects of dielectric permittivities on the thermally steady state temperature elevation and the temperature difference in the skin of a one-dimensional three-layer model due to MMW exposure.</p

<ORIGINAL>Quantification of Porphyromonas gingivalis by real time PCR : new primers targeting the rgpA and rgpB gene encoding RGP

We designed new primers for the quantification of Porphyromonas gingivalis by real time PCR. The new primer set targeted the rgpA and rgpB genes that encode arginine specific cysteine proteinase (Arggingipain or Rgp), one of the putative pathogenic factors of P. gingivalis. The PCR product obtained using our primers showed no by-products by melting curve analysis. The PCR product sequence showed no significant matches to other sequences by BLAST searching of genetic databases except for matches to P. gingivalis rgpA and rgpB sequence, and could not be amplified from template derived from other oral bacteria apart from P. gingivalis. Therefore, we concluded that our primers were specific for P. gingivalis rgpA and rgpB, and could be used to quantity from 10^3 to 10^7 P. gingivalis cells when applied to real time PCR

Human Exposure to Radiofrequency Energy above 6 GHz: Review of Computational Dosimetry Studies

International guidelines/standards for human protection from electromagnetic fields have been revised recently, especially for frequencies above 6 GHz where new wireless communication systems have been deployed. Above this frequency a new physical quantity "absorbed/epithelia power density" has been adopted as a dose metric. Then, the permissible level of external field strength/power density is derived for practical assessment. In addition, a new physical quantity, fluence or absorbed energy density, is introduced for protection from brief pulses (especially for shorter than 10 sec). These limits were explicitly designed to avoid excessive increases in tissue temperature, based on electromagnetic and thermal modeling studies but supported by experimental data where available. This paper reviews the studies on the computational modeling/dosimetry which are related to the revision of the guidelines/standards. The comparisons with experimental data as well as an analytic solution are also been presented. Future research needs and additional comments on the revision will also be mentioned.Comment: 38 pages, 3 figure

Roots-eye view: using microdialysis and microCT to non-destructively map root nutrient depletion and accumulation zones

Improvement in fertiliser use efficiency is a key aspect for achieving sustainable agriculture in order to minimise costs, greenhouse gas emissions and pollution from nutrient runoff. To optimise root architecture for nutrient uptake and efficiency we need to understand what the roots encounter in their environment. Traditional methods of nutrient sampling such as salt extractions can only be done at the end of an experiment, are impractical for sampling locations precisely and give total nutrient values which can overestimate the nutrients available to the roots. In contrast, microdialysis provides a non-invasive, continuous method for sampling available nutrients in the soil. Here for the first time we have used microCT imaging to position microdialysis probes at known distances from the roots and then measured the available nitrate and ammonium. We found that nitrate accumulated close to roots while ammonium was depleted demonstrating that this combination of complementary techniques provides a unique ability to measure root-available nutrients non-destructively and in almost real-time

Studies on Grass Productivity of Steep Mountainous Grassland (IV) A Comparison of Grass-Ladino Clover Mixures as Pastures for Young Steers on Steep Mountainous Grassland

急傾斜山地草地の不耕起造成用草種としてのオーチャードグラス,トールフェスク,レッドトップの各草地にラジノクローバを混播した時の家畜の生産性と草地植生の影響を調査し,急傾斜山地草地におけるラジノクローバ混播に関する知見をうるために,1970年と1971年の2か年間,黒毛和種若令去勢牛を用いて放牧実験を行なった. 得られた結果の概要は次のとおりである. 1)放牧期間中の1目1頭当たり増体量の2か年間の平均はオーチャードグラス・クローバ草地620g,卜ールフェスク・クローバ草地621g,レッドトップ・クローバ草地615gであった. 2)イネ科単播草地ヘクローバを混播することによって増体盤の増加がみとめられた. 3)オーチャードグラスとトールフェスク草地ではクローバの混播により裸地が著しく減少したが,レッドトップ草地では余り影響がみられなかった. 4)レッドトップ・クローバ草地ではクローバが優勢化しやすく放牧牛に鼓脹症の発生がみられた. 5)肥沃条件下ではレッドトップにラジノクローバを混播することは余りこのましくない

Prediction of POPF using CRP after LG

Purpose : Postoperative pancreatic fistula (POPF) is a serious complication after gastrectomy for gastric cancer. The purpose of this study is to identify the risk factor of POPF and evaluate C-reactive protein on postoperative day 1 (POD1) as the predictor for POPF after laparoscopic gastrectomy (LG). Methods : Between May 2013 and September 2016, 226 patients who underwent LG for gastric cancer were investigated. Patients were divided into 2 groups; POPF group (n = 17) and control group (n = 209). Clinicopathological factors were compared between 2 groups. Results : In POPF group, there are more male patients (p = 0.003) compared with control group. Preoperative factors, such as age, BMI, and prevalence of previous operation and comorbidity showed no significant difference between 2 groups. Regarding tumor factors and perioperative data such as blood loss and operative time, there were also no significant difference between 2 groups. POPF group showed longer postoperative hospital stay, and higher serum CRP level on POD1 (p < 0.0001). Multivariate analysis revealed that high CRP level on POD1 ( ≥ 3mg/dl) was independent risk factor of POPF. Conclusions : High serum CRP level on POD1 can predict the occurrence of POPF

Genome evolution in the allotetraploid frog Xenopus laevis

To explore the origins and consequences of tetraploidy in the African clawed frog, we sequenced the Xenopus laevis genome and compared it to the related diploid X. tropicalis genome. We characterize the allotetraploid origin of X. laevis by partitioning its genome into two homoeologous subgenomes, marked by distinct families of ???fossil??? transposable elements. On the basis of the activity of these elements and the age of hundreds of unitary pseudogenes, we estimate that the two diploid progenitor species diverged around 34 million years ago (Ma) and combined to form an allotetraploid around 17-18 Ma. More than 56% of all genes were retained in two homoeologous copies. Protein function, gene expression, and the amount of conserved flanking sequence all correlate with retention rates. The subgenomes have evolved asymmetrically, with one chromosome set more often preserving the ancestral state and the other experiencing more gene loss, deletion, rearrangement, and reduced gene expression.ope