scholarly journals Numerical modelling and experimental verification of thermal effects in living cells exposed to high-power pulses of THz radiation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
D. S. Sitnikov ◽  
A. A. Pronkin ◽  
I. V. Ilina ◽  
V. A. Revkova ◽  
M. A. Konoplyannikov ◽  
...  
Keyword(s):  
Numerical Modelling ◽  
Thermal Effect ◽  
High Power ◽  
Repetition Rate ◽  
Numerical Solutions ◽  
Biological Tissues ◽  
Dermal Fibroblasts ◽  
Thz Radiation ◽  
Fe Model ◽  
Significant Difference

AbstractExposure of cells or biological tissues to high-power pulses of terahertz (THz) radiation leads to changes in a variety of intracellular processes. However, the role of heating effects due to strong absorption of THz radiation by water molecules still stays unclear. In this study, we performed numerical modelling in order to estimate the thermal impact on water of a single THz pulse as well as a series of THz pulses. A finite-element (FE) model that provides numerical solutions for the heat conduction equation is employed to compute the temperature increase. A simple expression for temperature estimation in the center of the spot of THz radiation is presented for given frequency and fluence of the THz pulse. It has been demonstrated that thermal effect is determined by either the average power of radiation or by the fluence of a single THz pulse depending on pulse repetition rate. Human dermal fibroblasts have been exposed to THz pulses (with an energy of $$15\,\upmu \hbox {J}$$ 15 μ J and repetition rate of 100 Hz) to estimate the thermal effect. Analysis of heat shock proteins expression has demonstrated no statistically significant difference ($$p < 0.05$$ p < 0.05 ) between control and experimental groups after 3 h of irradiation.

scholarly journals Dopamine adjusts the circadian gene expression of Per2 and Per3 in human dermal fibroblasts from ADHD patients

2021 ◽  
Author(s):  
Frank Faltraco ◽  
Denise Palm ◽  
Adriana Uzoni ◽  
Lena Borchert ◽  
Frederick Simon ◽  
...  
Keyword(s):  
Gene Expression ◽  
Dermal Fibroblast ◽  
Sleep Onset ◽  
Dermal Fibroblasts ◽  
Control Group ◽  
Adhd Group ◽  
Healthy Controls ◽  
Circadian Gene ◽  
Significant Difference ◽  
Circadian Preference

AbstractA link between dopamine levels, circadian gene expression, and attention deficit hyperactivity disorder (ADHD) has already been demonstrated. The aim of this study was to investigate the extent of these relationships by measuring circadian gene expression in primary human-derived dermal fibroblast cultures (HDF) after dopamine exposure. We analyzed circadian preference, behavioral circadian and sleep parameters as well as the circadian gene expression in a cohort of healthy controls and participants with ADHD. Circadian preference was evaluated with German Morningness-Eveningness-Questionnaire (D-MEQ) and rhythms of sleep/wake behavior were assessed via actigraphy. After ex vivo exposure to different dopamine concentrations in human dermal fibroblast (HDF) cultures, the rhythmicity of circadian gene expression (Clock, Bmal1, Per1-3, Cry1) was analyzed via qRT-PCR. We found no statistical significant effect in the actigraphy of both groups (healthy controls, ADHD group) for mid-sleep on weekend days, mid-sleep on weekdays, social jetlag, wake after sleep onset, and total number of wake bouts. D-MEQ scores indicated that healthy controls had no evening preference, whereas subjects with ADHD displayed both definitive and moderate evening preferences. Dopamine has no effect on Per3 expression in healthy controls, but produces a significant difference in the ADHD group at ZT24 and ZT28. In the ADHD group, incubation with dopamine, either 1 µM or 10 µM, resulted in an adjustment of Per3 expression to control levels. A similar effect also was found in the expression of Per2. Statistical significant differences in the expression of Per2 (ZT4) in the control group compared to the ADHD group were found, following incubation with dopamine. The present study illustrates that dopamine impacts on circadian function. The results lead to the suggestion that dopamine may improve the sleep quality as well as ADHD symptoms by adjustment of the circadian gene expression, especially for Per2 and Per3.

scholarly journals Is There Pathological Uniformity between the Periphery and Center of a Gastrointestinal Stromal Tumor?

2021 ◽  
Vol 10 (4) ◽  
pp. 687
Author(s):  
Seong Ji Choi ◽  
Kwan Hong Lee ◽  
Chan Kyoo Yoo ◽  
Jai Hoon Yoon ◽  
Ki Seok Jang ◽  
...  
Keyword(s):  
Risk Stratification ◽  
Mitotic Index ◽  
High Power ◽  
Malignant Potential ◽  
Mitotic Count ◽  
Pathological Diagnosis ◽  
High Power Field ◽  
Gastric Gists ◽  
Significant Difference ◽  
The Mean

Background: Gastrointestinal stromal tumors (GISTs) are mesenchymal tumors and have some malignant potential. Mitotic count is important for predicting the malignant potential of GISTs. Proper treatment of GISTs requires accurate pathological diagnosis. In general, endoscopic ultrasound-guided fine-needle aspiration and deep biopsy are used for pathological diagnosis of GIST before making decisions about surgery. This study sought to evaluate the pathological uniformity of gastric GISTs for mitotic index of the center and periphery of the GIST. Methods: We retrospectively reviewed the data of 37 gastric GIST patients who underwent wedge resection at Hanyang University Hospital. We used Armed Forces Institute of Pathology criteria to classify gastric GISTs. To determine the pathological uniformity of gastric GISTs, we compared GIST risk stratification between the center and periphery of GISTs. Results: The mean size of GISTs was 3.56 ± 2.10 cm. Three lesions were located in the antrum, 11 in the fundus, 9 in the cardia, and 14 in the body. The mean age of patients was 58.65 ± 9.44 years; 18 patients were male and 19 were female. Thirty-five patients (94.6%) showed the same level of risk stratification between the center and periphery of gastric GISTs, while two patients (5.4%) presented different levels of risk between the two sites. No significant difference in mitotic count was observed between the two sites (kappa value = 0.863; p = 0.001). Conclusions: Mitotic index category (either more than five mitoses per high-power field or five or fewer mitoses per high-power field) of GISTs showed good concurrence between the center and periphery.

Development of high-power KrF lasers with a pulse repetition rate up to 5 kHz

2000 ◽  
Vol 30 (9) ◽  
pp. 783-786 ◽  
Author(s):  
V M Borisov ◽  
A Yu Vinokhodov ◽  
V A Vodchits ◽  
A V El'tsov ◽  
A S Ivanov
Keyword(s):  
High Power ◽  
Repetition Rate ◽  
Pulse Repetition Rate ◽  
Pulse Repetition

GHz femtosecond processing with agile high-power laser

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Eric Audouard ◽  
Guillaume Bonamis ◽  
Clemens Hönninger ◽  
Eric Mottay
Keyword(s):  
High Power ◽  
Repetition Rate ◽  
Thermal Ablation ◽  
Femtosecond Lasers ◽  
Optimal Choice ◽  
Process Conditions ◽  
High Power Laser ◽  
Power Laser ◽  
Ablation Efficiency ◽  
High Power Lasers

Abstract Bursts of GHz repetition rate pulses can significantly improve the ablation efficiency of femtosecond lasers. Depending on the process conditions, thermal mechanisms can be promoted and controlled. GHz ablation therefore combines thermal and non-thermal ablation mechanisms. With an optimal choice of the burst duration, the non-thermal ablation can be highly enhanced by a heating phase due to the first pulses in the burst. The GHz burst mode can be considered as a key function for the “agility” of new high-power lasers.

Preliminary results of numerical simulation of submarine landslide-generated waves

2021 ◽  
Author(s):  
Ramtin Sabeti ◽  
Mohammad Heidarzadeh
Keyword(s):  
Numerical Simulation ◽  
Numerical Modelling ◽  
Numerical Solutions ◽  
Numerical Technique ◽  
Source Region ◽  
Three Dimensional ◽  
Terminal Velocity ◽  
Sensitivity Analyses ◽  
Physical Experiments ◽  
Set Up

&lt;p&gt;Landslide-generated waves have been major threats to coastal areas and have led to destruction and casualties. Their importance is undisputed, most recently demonstrated by the 2018 Anak Krakatau tsunami, causing several hundred fatalities. The accurate prediction of the maximum initial amplitude of landslide waves (&lt;em&gt;&amp;#951;&lt;sub&gt;max&lt;/sub&gt;&lt;/em&gt;) around the source region is a vital hazard indicator for coastal impact assessment. Laboratory experiments, analytical solutions and numerical modelling are three major methods to investigate the (&lt;em&gt;&amp;#951;&lt;sub&gt;max&lt;/sub&gt;&lt;/em&gt;). However, the numerical modelling approach provides a more flexible and cost- and time-efficient tool. This research presents a numerical simulation of tsunamis due to rigid landslides with consideration of submerged conditions. In particular, this simulation focuses on studying the effect of landslide parameters on &lt;em&gt;&amp;#951;&lt;sub&gt;max&lt;/sub&gt;.&lt;/em&gt; Results of simulations are compared with our conducted physical experiments at the Brunel University London (UK) to validate the numerical model.&lt;/p&gt;&lt;p&gt;We employ the fully three-dimensional computational fluid dynamics package, FLOW-3D Hydro for modelling the landslide-generated waves. This software benefit from the Volume of Fluid Method (VOF) as the numerical technique for tracking and locating the free surface. The geometry of the simulation is set up according to the wave tank of physical experiments (i.e. 0.26 m wide, 0.50 m deep and 4.0 m). In order to calibrate the simulation model based on the laboratory measurements, the friction coefficient between solid block and incline is changed to 0.41; likewise, the terminal velocity of the landslide is set to 0.87 m/s. Good agreement between the numerical solutions and the experimental results is found. Sensitivity analyses of landslide parameters (e.g. slide volume, water depth, etc.) on &lt;em&gt;&amp;#951;&lt;sub&gt;max &lt;/sub&gt;&lt;/em&gt;are performed. Dimensionless parameters are employed to study the sensitivity of the initial landslide waves to various landslide parameters.&lt;/p&gt;

scholarly journals Modelling of mirror mode structures as propagating slow magnetosonic solitons

2009 ◽  
Vol 27 (12) ◽  
pp. 4379-4389 ◽  
Author(s):  
K. Stasiewicz ◽  
C. Z. Cheng
Keyword(s):  
Numerical Modelling ◽  
Excellent Agreement ◽  
Plasma Flow ◽  
Numerical Solutions ◽  
Small Subset ◽  
Instability Condition ◽  
Magnetic Pulsations ◽  
Fluid Theory ◽  
Mirror Mode ◽  
Two Fluid

Abstract. Cluster measurements in the magnetosheath with spacecraft separations of 2000 km indicate that magnetic pulsations interpreted as mirror mode structures are not frozen in plasma flow, but do propagate with speeds of up to ~50 km/s. Properties of these pulsations are shown to be consistent with propagating slow magnetosonic solitons. By using nonlinear two fluid theory we demonstrate that the well known classical mirror instability condition corresponds to a small subset in a continuum of exponentially varying solutions. With the measured plasma moments we have determined parameters of the polybaric pressure model in the region of occurrence of mirror type structures and applied it to numerical modelling of these structures. In individual cases we obtain excellent agreement between observed mirror mode structures and numerical solutions for magnetosonic solitons.

5 kHz high repetition rate and high power XeCl excimer laser

1995 ◽  
Vol 66 (11) ◽  
pp. 5162-5164 ◽  
Author(s):  
Tatsumi Goto ◽  
Koji Kakizaki ◽  
Shigeyuki Takagi ◽  
Noboru Okamoto ◽  
Saburo Sato ◽  
...  
Keyword(s):  
Excimer Laser ◽  
High Power ◽  
Repetition Rate ◽  
High Repetition Rate ◽  
High Repetition ◽  
Xecl Excimer Laser
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