Correction to: Inverse heat transfer analysis in detecting tissue optical properties using laser.

The published online version contains a mistake in equation 2c.

Inverse heat transfer analysis in detecting tissue optical properties using laser.

A new methodology has been proposed to measure optical properties of homogeneous tissue where a laser beam is used to induce heat to a tissue. The induced heat increased the temperature inside the tissue, which is detected by a thermocouple. These readings are compared with that obtained from the solution of the finite element solution that used iterative values of optical properties in determining temperature distribution. The two temperature distributions are used to determine tissue optical properties using the Levenberg-Marquardt iteration. An accurate result is obtained in determining absorption coefficient and reduced scattering coefficient. The work is extended to obtain three parameters (i.e., absorption coefficient, scattering coefficient, and anisotropy). The only limitation is that the temperature readings have to be measured with a high-accuracy thermocouple (i.e., less than 0.4% of maximum-recorded temperature).

Yemen: Cholera outbreak and the ongoing armed conflict.

Yemen was affected by a major cholera epidemic in 2016, while a civil war, which has devastated the country since March 2015, has exacerbated the humanitarian situation. Cholera is a disease caused by the bacterium Vibrio cholera, thus this study aims to analyze the epidemiological features of the outbreak and explore the relation of the outbreak to the current armed conflict situation. The data were obtained from the national surveillance system in Yemen. This contains details of 15,074 cases registered as suspected cholera patients per governorate from week 39 to 52 in 2016. In addition to the data concerning cholera, other data on conflict-related injuries, and population movement (numbers of Internally Displaced Persons - IDPs - and number of displaced returnees) were used to assess the correlation using Spearman's rho analysis. The data analysis shows the intensity of the conflict as measured by the total casualties per governorate (conflict-related injuries and death) is significantly correlated with the number of cholera cases per governorate (r 0.483, P = 0.026). The analysis also shows a positive, but not significant correlation between cholera cases, and both the number of conflict internal displaced people (IDPs) (r 0.389, P = 0.081), and number of returnees (r = 432, P = 0.050).

The effect of laser power, blood perfusion, thermal and optical properties of human liver tissue on thermal damage in LITT.

In this work, the finite-element method (FEM) was used to predict the temperature distribution, and the thermal damage volume in human liver tissue subjected to laser in laser-induced interstitial thermotherapy (LITT). The effect of laser power, blood perfusion, and thermal and optical properties on maximum temperature and thermal damage volume were predicted using the finite-element method. A computer program was written in visual basic language, which was verified by comparing its result with data published elsewhere. The bio-heat equation together with the effect of linear laser source were used to simulate heat transfer through tissue from which the temperature distributions, and the subsequent thermal damage, were obtained based on Arrhenius equation. In this mathematical model for LITT, it was found that increasing laser power, absorption, and scattering coefficient increased the damage zone while increasing tissue water content, perfusion rate, and tissue anisotropy factor decreased the damage zone. These findings are important aspects for doctors in the pre-estimation of the damage zone before starting the therapy so as to kill only the desired zone.

Finite element analysis of cornea thermal damage due to pulse incidental far IR laser.

Due to the wide use of laser systems in human activities, an accidental event of laser exposure may occur where the most susceptible part to injury is the eye. A typical invisible pulsed, far IR, CO2 laser beam was used as an intrabeam accidentally struck an eye leading to raise its temperature to a limit where a pain sensation was started followed by aversion response with a delay of 0.25 s. At this time, the laser beam was assumed to terminate with respect to the cornea. The finite element method (FEM) was used successfully to predict, numerically, the temperature distribution through the anterior part of the eye when subjected to the laser beam. The FEM program was written using Visual Basic 6 coding. The effects of laser parameters such as laser beam profile, pulse width, and repetition rate on the temperature distribution and the consequential thermal damage were studied. The efficiency of the constructed computer program of the present work was examined by the comparison of the predicted results with those obtained from previously published experimental and theoretical works. The comparison shows good agreements.