Performance Evaluation of Temperature-Based Global Solar Radiation Models—Case Study: Arar City, KSA

Solar radiation is considered the main renewable energy source which reshapes the global sustainability plan for future development. Due to the lack of solar radiation measurements, this work investigates the performance of several temperature-based hybrid solar radiation models combining the parametric, statistical and satellite data approaches to estimate the global solar radiation on a horizontal surface. Over 35 years of meteorological data in the new location, Arar City, KSA (Latitude 30°96′ N and longitude 41°05′ E) are employed to establish and validate the models. These models are validated using two datasets with different averaging time spans to investigate the accuracy and reliability of different models as forecasting tools for the solar radiation. The mostly common statistical indicators are calculated to identify the most accurate model. The results show that Model (1) has the best performance among all models with high reliability as a solar radiation forecasting tool in this new location. This model is also validated against the widely-used datasets, namely NASA, On-Site measurements and PVGIS-SARAH data. The model shows excellent values for statistical indicators with high values of coefficient of determination, R2 > 0.955, presenting the best performance regardless of the time span of the validation datasets.

Randomised crossover trial comparing algorithms and averaging times for automatic oxygen control in preterm infants

ObjectiveAutomatic control (SPOC) of the fraction of inspired oxygen (FiO2), based on continuous analysis of pulse oximeter saturation (SpO2), improves the proportion of time preterm infants spend within a specified SpO2-target range (Target%). We evaluated if a revised SPOC algorithm (SPOCnew, including an upper limit for FiO2) compared to both routine manual control (RMC) and the previously tested algorithm (SPOCold, unrestricted maximum FiO2) increases Target%, and evaluated the effect of the pulse oximeter’s averaging time on controlling the SpO2 signal during SPOC periods.DesignUnblinded, randomised controlled crossover study comparing 2 SPOC algorithms and 2 SpO2 averaging times in random order: 12 hours SPOCnew and 12 hours SPOCold (averaging time 2 s or 8 s for 6 hours each) were compared with 6-hour RMC. A generated list of random numbers was used for allocation sequence.SettingUniversity-affiliated tertiary neonatal intensive care unit, GermanyPatientsTwenty-four infants on non-invasive respiratory support with FiO2 >0.21 were analysed (median gestational age at birth, birth weight and age at randomisation were 25.3 weeks, 585 g and 30 days).Main outcome measureTarget%.ResultsMean (SD) [95% CI] Target% was 56% (9) [52, 59] for RMC versus 69% (9) [65, 72] for SPOCold_2s, 70% (7) [67, 73] for SPOCnew_2s, 71% (8) [68, 74] for SPOCold_8s and 72% (8) [69, 75] for SPOCnew_8s.ConclusionsIrrespective of SpO2-averaging time, Target% was higher with both SPOC algorithms compared to RMC. Despite limiting the maximum FiO2, SPOCnew remained significantly better at maintaining SpO2 within target range compared to RMC.Trial registrationNCT03785899

Гігієнічні нормативи хімічних речовин в атмосферному повітрі: досягнення минулого та сучасні погляди у майбутнє

Objective: We generalized and assessed the prior chemical pollutants in accordance with the time of their averaging by the data of domestic and foreign regulatory frameworks. Materials and methods: To achieve the goal, we used the bibliographic and analytical methods. We analyzed the databases of Ukraine and the EU countries, the USA and Canada on the current standards for chemical agents and the time of their averaging in accordance with the purpose - prevention of acute and chronic effects. Results and discussion: As a result of the comparison of the data on the regulations and standards for chemical agents in ambient air, we identified the agents that are criterial ones in most countires. For these substances, monitoring methods have been developed and standards have been substantiated and adopted for two averaging periods: twenty-minute and average daily. In most countries, two standards have been also adopted for each agent, but the averaging period is longer there: an average annual and a daily average. Such standards may control and prevent the chronic effect of substances. As a result, the use of the Ukrainian and foreign standards leads to the controversial estimates of the actual air pollution. The average daily standard adopted in Ukraine, on the one hand, is much stricter in comparison with the similar foreign criteria, and on the other hand, it does not correspond to the peculiarities of the formation of ambient air pollution, and is inadequate for the averaging time. Conclusions: 1. Comparative analysis of hygienic standards indicates the needs to harmonize the ambient air quality standards in force in Ukraine with international ones. 2. The existing system of the hygienic standards in Ukraine must be supplemented with the standard for the annual averaging period by transferring the operating average daily concentrations to this rank.

Dependence of SpO2 signal noise on the pulse oximeter averaging time

A model of the pulse oximeter, which consists of a transfer function between arterial and peripheral blood oxygen saturation (SpO2) and the noise typical for SpO2 records, is an important part of a mathematical model of oxygenation in neonates that is designed to test and compare different algorithms of oxygen control. The noise level in the SpO2 signal is affected by the averaging time setting of the pulse oximeter. This study aimed to characterize the noise level in the SpO2 signal at the set pulse oximeter averaging times of 2- 4, 8, and 16 seconds. We evaluated SpO2 records of 17 healthy volunteers who underwent a laboratory experiment in which they evoked different types of artifacts. The noise level in the SpO2 signal was characterized by two parameters, the deviation of SpO2 from the true value and the SpO2 time stability, defined as the interval during which the measured SpO2 value remained unchanged. Statistical properties of the noise level for the three averaging times were represented by normalized histograms of both the parameters and varied according to the type of artifact. With motion artifacts, the SpO2 readings deviated from the true value by more than ±2% SpO2 in 10%, 7%, or 5% of the measurements when the set averaging time was 2-4 s, 8 s, or 16 s. The length of the interval over which the SpO2 value remained unchanged was most frequently 2 seconds for all set averaging times. Implementation of the noise characteristics into the computer model of oxygenation in neonates will allow more faithful simulations of the output SpO2 signal that better match clinical observations.

P035 Is the Grael oximetry averaging time interchangeable with a Masimo pulse oximeter algorithm in polysomnography?

Compumedics recording software (Grael V2) for polysomnography (PSG) calculates SpO2 values using a 3-heartbeat long averaging window. This is derived from the ECG and thus introduces variability in the averaging time that is dependent on the heart rate. Little is known about the effect this has on the common oximetry metrics used in PSG interpretation. This study explorer the interchangeability of the Grael V2 inbuilt 3-beat averaging algorithm with a short averaging window of 2 - 4 seconds using a Masimo Radical 7 pulse oximeter during a PSG. SpO2 data were collected from 2 oximeter probes (Grael and Radical 7) both attached to a patient’s fingers. After SpO2 artifacts were removed, the following SpO2 parameters from each oximeter were generated: mean sleep SpO2, oxygen desaturation index (ODI) using 2%, 3% and 4% drop in SpO2 in sleep, total sleep time (TST) with SpO2 < 90% and < 80% as well as time spent < SpO2 88% in minutes. 88 sleep studies were included in the data collection. For ODI2%, 3% and 4%, bias (95% limits of agreement) values were -0.75 events/hr (9.99 to -11.49 events/hr), -0.74 events/hr (10.00 - -11.49 events/hr) and -0.20 events/hr (8.45 - -8.86 events/hr) respectively. There was no significant difference between measurements except for the mean sleep SpO2 values, p < .001. Although no bias found between measurements, there was poor agreement between the algorithms as demonstrated by the wide 95% limits of agreement suggesting that the two oximeter devices are not interchangeable.

Locking Multi-Laser Frequencies to a Precision Wavelength Meter: Application to Cold Atoms

We herein report a simultaneous frequency stabilization of two 780-nm external cavity diode lasers using a precision wavelength meter (WLM). The laser lock performance is characterized by the Allan deviation measurement in which we find σy=10−12 at an averaging time of 1000 s. We also obtain spectral profiles through a heterodyne spectroscopy, identifying the contribution of white and flicker noises to the laser linewidth. The frequency drift of the WLM is measured to be about 2.0(4) MHz over 36 h. Utilizing the two lasers as a cooling and repumping field, we demonstrate a magneto-optical trap of 87Rb atoms near a high-finesse optical cavity. Our laser stabilization technique operates at broad wavelength range without a radio frequency element.

Molecular Brightness Approach for FRET Analysis of Donor-Linker-Acceptor Constructs at the Single Molecule Level: A Concept

In this report, we have developed a simple approach using single-detector fluorescence autocorrelation spectroscopy (FCS) to investigate the Förster resonance energy transfer (FRET) of genetically encoded, freely diffusing crTC2.1 (mTurquoise2.1–linker–mCitrine) at the single molecule level. We hypothesize that the molecular brightness of the freely diffusing donor (mTurquoise2.1) in the presence of the acceptor (mCitrine) is lower than that of the donor alone due to FRET. To test this hypothesis, the fluorescence fluctuation signal and number of molecules of freely diffusing construct were measured using FCS to calculate the molecular brightness of the donor, excited at 405 nm and detected at 475/50 nm, in the presence and absence of the acceptor. Our results indicate that the molecular brightness of cleaved crTC2.1 in a buffer is larger than that of the intact counterpart under 405-nm excitation. The energy transfer efficiency at the single molecule level is larger and more spread in values as compared with the ensemble-averaging time-resolved fluorescence measurements. In contrast, the molecular brightness of the intact crTC2.1, under 488 nm excitation of the acceptor (531/40 nm detection), is the same or slightly larger than that of the cleaved counterpart. These FCS-FRET measurements on freely diffusing donor-acceptor pairs are independent of the precise time constants associated with autocorrelation curves due to the presence of potential photophysical processes. Ultimately, when used in living cells, the proposed approach would only require a low expression level of these genetically encoded constructs, helping to limit potential interference with the cell machinery.

Simultaneous bicolor interrogation in thulium optical clock providing very low systematic frequency shifts

Optical atomic clocks have already overcome the eighteenth decimal digit of instability and uncertainty, demonstrating incredible control over external perturbations of the clock transition frequency. At the same time, there is an increasing demand for atomic (ionic) transitions and new interrogation and readout protocols providing minimal sensitivity to external fields and possessing practical operational wavelengths. One of the goals is to simplify the clock operation while maintaining the relative uncertainty at a low 10−18 level achieved at the shortest averaging time. This is especially important for transportable and envisioned space-based optical clocks. Here, we demonstrate implementation of a synthetic frequency approach for a thulium optical clock with simultaneous optical interrogation of two clock transitions. Our experiment shows suppression of the quadratic Zeeman shift by at least three orders of magnitude. The effect of the tensor lattice Stark shift in thulium can also be reduced to below 10−18 in fractional frequency units. This makes the thulium optical clock almost free from hard-to-control systematic shifts. The “simultaneous” protocol demonstrates very low sensitivity to the cross-talks between individual clock transitions during interrogation and readout.