RETINAL SPECTRAL IMAGING AND BLOOD FLOW MEASUREMENT

Measurement of both oxygen saturation and blood flow in the retinal vessels has proved to give important information about the eye health and the onset of eye pathologies such as diabetic retinopathy.In this study,we present the implementation,on a commercially available fundus camera,of a retinal imager and a retina blood flow velocimeter.The retinal imager uses division of aperture to acquire nine wavelength-dependent sub-images of the retina.Careful consideration is taken to improve image transfer by measuring the optical properties of the fundus camera and modeling the optical train in Zemax.This part of the setup is calibrated with optical phantoms of known optical properties that are also used to build a lookup table(LUT)linking phantom optical properties to measured reflectance.The retina blood flow velocimeter relies on tracking clusters of erythrocytes and uses a fast acquisition camera attached to a zoom lens,with a green illumination LED-engine.Calibration is provided using a calibrated quartz capillary tube and human blood at a known flow rate.Optical properties of liquid phantoms are retrieved from measured reflectance using the LUT,and blood flow measurements in the retina are presented.

Evaluation of photon beam dose calculation accuracy of treatment planning systems using in vivo dosimetry

Objective The treatment planning system currently represents one of the basics of radiation therapy,because it is the only method to estimate patient dose delivery fast forward and accurately represent estimated tumor location of the tumor with the possibility of estimating densities in the tissue surrounding the tumor to overcome dose calculation defects but radial estimated the patient.Despite the flaws associated with the systems and calculates the dose of your programs in all programs currently existing in the world.Than necessary,to the existence of a review of the accuracy of accounts and how to confirm the radiation dose to the patient programs.Methods A total of 35 cancer patients were considered for this study,with 245 field measurements made with low-and high-energy diode detectors for brain and prostate cases.The treatments for all patients were planned using Eclipse Treatment Planning System version 13.6.Results Of the 105 field measurements made for the prostate cancer patients,16 included discrepancies outside the ±5% action level.Of the 145 measurements taken of the brain cases,there were four outside the ±5% action level.The results indicated a higher degree of accuracy.The study revealed that,for the prostate measurements,the higher discrepancy in the doses for the particular fields(exceeding the action level) may have been due to the isocenter being very close to the jaws and multi-leaf collimator of the linear accelerator machine.As a result,scatter from the jaws and the multi-leaf collimator could have contributed to the high dose delivered to the diode;hence,a probable higher discrepancy of the dose in more brain cases due highest quality of VMAT technique and fixation system.Conclusion A greater percentage of the observed discrepancies were well within the set tolerance level.However,it is recommended that the positioning of the diode on the patient's skin and the angular sensitivity of the diodes be reconsidered.It is also recommended that a more accurate calculation of expected diode values be performed,especially for fields that pass through the table.These efforts would achieve action levels of ±5%.

A New Approach for Converting Renewable Energy to Stable Energy

A renewable energy plant which relies on wind speed or solar insolation is unreliable because of the stochastic nature of weather patterns. It is theorized that by using multiple renewable energy plants in separate areas of a region, the different weather conditions might approach a probabilistically independent relationship. The goal of this paper is to utilize the power system technology to help disseminate wind and solar power systems to get a stable energy. A new approach to get appropriate stable energy is achieved by using the interrupted energy that obtained from wind farm and solar insolation. This is achieved by lifting water to a higher level with appropriate pumps and storing it in the form of potential energy. Then a stable energy is obtained by reliving water to the lower level. In this paper, the efficiency obtained from the renewable energy is compared with that obtained from traditional ones. An experimental model to simulate the process of converting the renewable energy to a stable energy is presented. The obtained results from experimental model explained that the renewable energy can be converted to a stable one with high efficiency.

Why is the Omicron main protease of SARS-CoV-2 less stable than its wild-type counterpart?A crystallographic,biophysical,and theoretical study

During the continuing evolution of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),the Omicron variant of concern emerged in the second half of 2021 and has been dominant since November of that year.Along with its sublineages,it has maintained a prominent role ever since.The Nsp5 main protease(Mpro)of the Omicron virus is characterized by a single dominant mutation,P132H.Here we determined the X-ray crystal structures of the P132H mutant(or O-Mpro)as a free enzyme and in complex with the Mpro inhibitor,the alpha-ketoamide 13b-K,and we conducted enzymological,biophysical,as well as theoretical studies to characterize the O-Mpro.We found that O-Mpro has a similar overall structure and binding with 13b-K;however,it displays lower enzymatic activity and lower thermal stability compared to the WT-Mpro(with“WT”referring to the prototype strain).Intriguingly,the imidazole ring of His132 and the carboxylate plane of Glu240 are in a stacked configuration in the X-ray structures determined here.Empirical folding free energy calculations suggest that the O-Mpro dimer is destabilized relative to the WT-Mpro due to less favorable van der Waals interactions and backbone conformations in the individual protomers.All-atom continuous constant-pH molecular dynamics(MD)simulations reveal that His132 and Glu240 display coupled titration.At pH 7,His132 is predominantly neutral and in a stacked configuration with respect to Glu240 which is charged.In order to examine whether the Omicron mutation eases the emergence of further Mpro mutations,we also analyzed the P132H+T169S double mutant,which is characteristic of the BA.1.1.2 lineage.However,we found little evidence of a correlation between the two mutation sites.