Low mAs Research Articles

Delineating the effects of ignition propensity and Markstein number on deflagration-to-detonation transition

Although the process through which a deflagration transitions to a detonation (DDT) has been studied for over a century, it is not well-understood how the propensity for DDT varies among different combustible mixtures. We investigate the effect of two fundamental mixture properties, ignition delay (τign) and Markstein number (Ma), on this stochastic process. Experiments were conducted in a smooth cylindrical tube, and the critical state (characterized by the velocity of the reacting front) at which a detonation formed from an accelerating deflagration was measured. The novelty of the study lies in the selection of mixture compositions that enabled changing only one relevant combustion property at a time and hence isolating the sensitivity to that property. Experiments with mixtures with similar deflagrative properties but different τign revealed that the critical state is not measurably sensitive to ignition propensity. Mixtures studied with different thermo-diffusive properties revealed that Ma has a strong effect on the critical state. Specifically, thermo-diffusively-unstable mixtures (with low Ma) underwent DDT at significantly lower velocities. Furthermore, experiments were performed with and without a spiral to isolate the effect of flame wrinkling and turbulence. The spiral-affected flames underwent DDT at lower velocities, similar to thermo-diffusively-unstable mixtures. This observed effect of thermo-diffusive nature of the mixture and turbulence on DDT propensity is not predicted by existing models.

On the properties and implications of collapse-driven MHD turbulence

ABSTRACT We investigate the driving of MHD turbulence by gravitational contraction using simulations of an initially spherical, isothermal, magnetically supercritical molecular cloud core with transonic and trans-Alfvénic turbulence. We perform a Helmholtz decomposition of the velocity field, and investigate the evolution of its solenoidal and compressible parts, as well as of the velocity component along the gravitational acceleration vector, a proxy for the infall component of the velocity field. We find that (1) In spite of being supercritical, the core first contracts to a sheet perpendicular to the mean magnetic field, and the sheet itself collapses. (2) The solenoidal component of the turbulence remains at roughly its initial level throughout the simulation, while the compressible component increases continuously, implying that turbulence does not dissipate towards the centre of the core. (3) The distribution of simulation cells in the B–ρ plane occupies a wide triangular region at low densities, bounded below by the expected trend for fast MHD waves (B ∝ ρ, applicable for high-local Alfvénic Mach number MA) and above by the trend expected for slow waves (B ∼ constant, applicable for low local MA). At high densities, the distribution follows a single trend $B \propto \rho ^{\gamma _{\rm eff}}$, with 1/2 < γeff < 2/3, as expected for gravitational compression. (4) The mass-to-magnetic flux ratio λ increases with radius r due to the different scalings of the mass and magnetic flux with r. At a fixed radius, λ increases with time due to the accretion of material along field lines. (5) The solenoidal energy fraction is much smaller than the total turbulent component, indicating that the collapse drives the turbulence mainly compressibly, even in directions orthogonal to that of the collapse.

Comparison of dexmedetomidine and a dexmedetomidine-esketamine combination for reducing dental anxiety in preschool children undergoing dental treatment under general anesthesia: A randomized controlled trial

BackgroundDental anxiety is a widespread complication occurring in pediatric patients during dental visits and may lead to undesirable complications. Esketamine may be effective in anxiety. ObjectiveThe objective of this study was to investigate the effect of premedication with a dexmedetomidine-esketamine combination compared with dexmedetomidine alone on dental anxiety in preschool children undergoing dental treatment under general anesthesia. MethodsThis is a prospective, double-blinded, randomized controlled trial. A total of 84 patients were scheduled for elective outpatient dental caries treatment under general anesthesia. Patients were randomly premedicated with intranasal dexmedetomidine (group D) or intranasal dexmedetomidine-esketamine (group DS).The primary outcome was the level of dental anxiety assessed by the Modified Child Dental Anxiety Scale (MCDAS) at 2 h after surgery. Secondary outcomes included level of dental anxiety at 1 day and 7 days after surgery, the incidence of dental anxiety at 2 h, 1 day, and 7 days after surgery, sedation onset time, overall success of sedation, acceptance of mask induction, postoperative pain intensity, incidence of emergence agitation in PACU, adverse reactions, HR, and SpO2 before premedication (baseline) and at 10, 20, and 30 min after the end of study drug delivery. ResultsThe dental anxiety in group DS was lower than that in group D at 2 h, 1 day, and 7 days postoperatively (P = 0.04, 0.004, and 0.006, respectively). The incidences of dental anxiety in group DS were lower than those in group D at 2 h (53 % vs 76 %, P = 0.03), 1 day (47 % vs 71 %, P = 0.04), and 7 days (44 % vs 71 %, P = 0.02) after surgery. Group DS had a higher success rate of sedation (P = 0.03) but showed a lower MAS score (P = 0.005) and smoother hemodynamics (P < 0.01) after drug administration than group D. Group DS showed a significantly lower incidence rate of emergence agitation (P = 0.03) and postoperative pain intensity (P = 0.006) than that in group D during the anesthesia recovery time. The occurrence of adverse reactions was similar in both groups (P > 0.05). LimitationsWe did not analyze and correct for the learning effect caused by repeated applications of the MCDAS and MCDAS scores on the 1 day after surgery were obtained by telephone follow-up. ConclusionsCompared to premedication with dexmedetomidine alone, premedication with intranasal dexmedetomidine combined with esketamine could significantly improve dental anxiety in preschool children undergoing dental treatment under general anesthesia.

Developmental trajectories of number line estimations in math anxiety: Evidence from bounded and unbounded number line estimation

AbstractMathematical anxiety (MA) is a feeling of tension and anxiety that interferes with the manipulation of numbers and the solution of mathematical problems. Past studies have shown that high MA individuals experience difficulties at different levels and domains of mathematics, and that MA results from weakness in spatial abilities, subsequent to deficits in basic numerical abilities. Hence, the main goal of the present study is to examine developmental trajectories of number space associations and their role in MA. In the present study, 2nd, 3rd, and 5th grade children (n = 94) participated in number line estimation tasks, half with low MA (LMA) and half with high MA (HMA). They performed two number line estimation tasks (bounded‐ with numerical values for beginning and end of the number line, or unbounded‐ only the beginning of the number line is marked) in addition to examination of strategy during arithmetical problems. Results indicated that younger children with HMA showed non‐mature numerical estimations compared to participants with LMA. However, for older HMA children, estimations were normalized and group differences were eliminated. Moreover, we found that estimations predicted usage of advanced memory‐based strategies in simple addition operations. These results indicated that (1) non‐mature numerical estimations characterize younger participants with MA, and (2) that numerical estimations are associated with arithmetical performances.

Investigation of the Relationship between Body Parameters and mAs Using Non-Contact Two-Dimensional Thickness Measurement in Chest Digital Radiography.

The current study aimed to investigate the relationship between body parameters and the current-time product (mAs) in chest digital radiography using a non-contact infrared thickness-measurement sensor. An anthropomorphic chest phantom was first used to understand variations in mAs over multiple positionings during chest radiography when using the automatic exposure control (AEC) technique. In a human study, 929 consecutive male subjects who underwent regular chest examinations were enrolled, and their height (H), weight (W), and body mass index (BMI) were recorded. In addition, their chest thickness (T) was measured at exhalation using a non-contact infrared sensor, and chest radiography was then performed using the AEC technique. Finally, the relationship between four body parameters (T, BMI, T*BMI, and W/H) and mAs was investigated by fitting the body parameters to mAs using three curve models. The phantom study showed that the maximum mAs was 1.76 times higher than the lowest mAs during multiple positionings in chest radiography. In the human study, all chest radiographs passed the routine quality control procedure and had an exposure index between 100 and 212. In curve fitting, the comparisons showed that W/H had a closer relationship with mAs than the other body parameters, while the first-order power model with W/H fitted to mAs performed the best and had an R-square of 0.9971. We concluded that the relationship between W/H and mAs in the first-order power model may be helpful in predicting the optimal mAs and reducing the radiation dose for chest radiography when using the AEC technique.

ANALISA KEPATUHAN PENGGUNAAN DOSE CONSTRAINT DI INSTALASI RADIOLOGI RUMAH SAKIT SEBAGAI IMPLEMENTASI ASAS OPTIMISASI DALAM KESELAMATAN RADIASI

Background: No data has yet been found regarding the evaluation of the use of Dose Constraints in a hospital radiology installation. The purpose of this study was to determine the percentage of adherence to the use of dose constraints in a radiology installation as well as analysis and follow-up.&#x0D; Methods: The research was conducted by making observations at 30 Hospitals on the island of Java, the researchers distributed a questionnaire survey in the form of 20 data using the exposure factor for Thorax PA examination which would then be inputted through the Si-INTAN application to obtain ESAK values.&#x0D; Results: Based on 600 data on the use of exposure factors from 30 samples of hospitals on the island of Java, it was found that 21 or 70% of the hospitals adhered to the use of dose constraints and as many as 9 or 30% of hospitals do not comply with the use of the determined dose constraint.&#x0D; Conclusions: Of the 9 hospitals that were not compliant with the use of the dose constraint, the highest ESAK value was obtained from RS-18, which was 0.939 mGy, which reached twice the stipulated I-DRL Thorax examination value. It can be seen that these hospitals used the most mAs. higher than other hospitals. The mAs values used range from 10-28 mAs. When compared with the lowest ESAK value, namely RS-3, it only uses 5 mAs for an adult thorax examination. to suppress ESAK doses to be lower we can use high tube voltages. to obtain an exposure with the same transmission at a patient thickness of 20 cm, namely by increasing one of the irradiation parameters of the tube voltage value by compensating for a decrease in the tube current-time value to produce an image density that is almost the same,and using very low mAs also results in a dose radiation is very small.

Usefulness Evaluation of Algorithm for Reducing Noise and Artifact in CT Guided Biopsy Using Fine Needles

This study analyzed the usefulness of standard, bone, edge and FBP, ASIR, ASIR-V, MAR algorithm to reduce noise caused by low mA and to reduce artifacts caused by fine needle. The CT number value measured through the phantom study was higher in order of MAR, edge, bone, and standard algorithm. In the case of using the ASIR-V in the algorithm excluding MAR, the noise value was reduced compared to the case of using ASIR. In particular, the edge algorithm showed an average noise reduction effect of 4.59times when ASIR-V was applied compared to other algorithms and also scored high in the sharpness of the fine needle. MAR algorithm has the highest CT number and the lowest noise value, but it is difficult to apply clinically because of the severe distortion of the fine needles. As a result of this study, it is considered that the application of edge algorithm with ASIR-V algorithm will be more useful than the application of MAR algorithm in CT examination using fine needles.

Finite-wing-analogy formula for compressibility correction to pressure coefficient of an underwater vehicle model at low Mach number

Wind tunnels are usually used to investigate the flows and forces associated with underwater vehicles when free-surface effects can be ignored. However, because of the large differences between air and water in density and viscosity, the freestream Mach number in a wind tunnel is much higher than that in a water tunnel or towing tank at the same Reynolds number. Therefore, compressibility correction is required for accurate measurement compatibility between wind tunnels and water tunnels or towing tanks. In the study reported here, the flows and forces associated with an underwater vehicle model at different Mach numbers were investigated by solving the Navier–Stokes equations for compressible flow numerically as virtual-wind tunnel experiments. The freestream Mach number Ma varies from 0.004 to 0.5. The distribution of the pressure coefficient on the hull and the effects of Ma on the peaks of the pressure coefficient are discussed in detail. The performances of the Prandtl–Glauert rule, the Karman–Tsien rule, and the Laitone rule for compressibility correction to the pressure coefficient of underwater vehicles are assessed. Defining the average correction factor with larger values for better correction effect, the values for these three compressibility correction formulas are 0.51, 0.38, and 0.23, respectively. A finite-wing-analogy formula to improve the compressibility correction to the pressure coefficient at low Ma is proposed. Inspired by the finite-wing correction to the lift slope of airfoils, the proposed formula offers good convergence of the pressure coefficient and highly accurate compressibility correction with an average correction factor of 0.84.

Evaluation of the different exposure parameters for the accurate diagnosis of peri-implantitis severity in digital panoramic radiography

To evaluate the accuracy of the diagnosis of peri-implant bone defects' severities in digital panoramic radiographs obtained at different tube voltage and/or tube current settings. Two different sizes of peri-implant bone defects (type 1 and type 2) were prepared after the implants were inserted into 29 bovine rib blocks. Digital panoramic radiographs were obtained at eight different tube voltage and/or tube current settings for all rib blocks. Implant images were cropped separately. The average intensity value (AIV) of cropped images were analyzed using Adobe Photoshop CC software. The Kruskal-Wallis H test was used to compare AIVs. All cropped images were evaluated using a five-point Likert scale for the likelihood of a bone defect being absent or present. The weighted kappa values were calculated to compare observer agreement and ROC analysis was performed to determine the appropriate exposure parameters. The lowest AIV was obtained at 72 kV/6.3 mA (92.162±16.016), and the highest AIV was obtained at 60 kV/3.2 mA (179.050±13.823). The Kruskal-Wallis H test showed significant differences in the AIVs according to the exposure parameters (p<0.001). The kappa coefficient for the inter-observer agreement was excellent (0.864, p<0.001). The AUC values for type 1 defects ranged from 0.778 and 0.860; for type 2 defects ranged from 0.920 and 0.967. The AUC value of type 1 defects was slightly better in panoramic images obtained with high kV and low mA levels (72 kV/3.2 mA), compared to others. In daily clinical routine, peri-implant bone defects might be evaluated by panoramic radiographs obtained with all kV and mA values tested. However, to avoid misdiagnosing and for better accuracy, panoramic radiographs obtained with high kV and low mA levels suitable for patients should be used, especially in the detection of small or initial bone defects.

Numerical study on a low mass flow rate cold compressor for 2 K helium cryogenic system

A cold compressor is a key equipment in a superfluid helium refrigeration system. It helps to make the 2 K helium refrigerator more compact, increase the cycle efficiency, and reduce the risk of air leakage. However, cold compressors have been applied only in relatively large 2 K helium refrigerators with mass flow rates of more than 25 g/s. To verify the feasibility of using a low mass flow rate cold compressor in the testing system of the China Initiative Accelerator Driven System (CiADS), the thermodynamic model of the 2 K cryogenic cycle was built. Then, a cold compressor with a low mas flow rate was designed, and its performance was numerically studied based on the one-dimensional self-written code and a three-dimensional computational fluid dynamics model, respectively. The total pressure ratio and isentropic efficiency of the cold compressor were 2.44 and 64.4 % at the design point of 3.5 g/s@36000 rpm, respectively. The small mass flow rate cold compressor was remarkably beneficial for the 2 K cryogenic systemas the exergy efficiency increased from 0.16 to 0.23 and the specific power consumption decreased from 604 W/W to 327 W/W. The research has preliminarily verified the practicality of using a small flow rate cold compressor in superfluid helium systems.

Computational realization of turbulent combustion in a scramjet combustor stabilized by a lobed strut

Currently, there are theoretical and technical challenges to organize stable flame in scramjet, especially for variable flight conditions. This paper applies the numerical simulation to investigate and analyze the combustion characteristics in a lobed strut-stabilized scramjet combustor under different conditions of Mach number (Ma). By comparing with the experiment date of hydrogen mole fraction, the reliability of large eddy simulation solver used in this paper is verified. On this basis, the simulations of mixing and combustion cases at Ma 1.5–3.0 are carried out separately. The numerical results show the streamwise vortices induced by the lobed strut enhance the mixing and are conducive to the subsequent stable combustion. The turbulent flame behaves lifted characteristics, and the auto-ignition provides the initial active radicals for its stabilization. There are two chemical reaction modes in the flow field, namely auto-ignition, and flame. Further comparison of the cases of different Mach numbers indicates that the lifted height of the flame depends on the Mach number. Analysis of probability density function (PDF) reveals that Mach number influent the competitive relationship between the auto-ignition mode and the flame mode. The auto-ignition and the flame coexist downstream in high ma cases, while the flame mode is the dominant in low Ma cases.

A comparative investigation of the synergistic correlation (mechanical-hydrophobicity/hydrophilicity vs. structural behaviors) of a series of surface-metalized polyacrylonitrile fibers by silver nanoparticles (AgPAN): An in-situ surface metallization protocol

Research problem The demand for polymeric materials is increasing day by day, provided that they have excellent virtues to meet desired needs. The best way to obtain high-quality polymeric materials was surface treatment in multiple methods. All the methods that have been used were expensive, multi-stage, harmful to the environment, and other shortages. Therefore, we sought in our paper to invent and develop a surface metallization protocol under green and safe conditions, based on integrating two safe methods for preparing nanomaterials (electrospinning/ultrasound) in one-pot. Aim of this work The main objective of this work is to answer a question that has been neglected in other papers: how does in-situ metallization affect the crystalline behavior of the semi-crystalline phase of the PAN matrix depending on different amounts of MA NPs and their synergy for the rest of the properties (morphological and structural) is presented, in first degree. In the second degree, an explanation of the synergy mechanism between the mechanical/hydrophilic properties and the modified structural properties of metalized fibers has explained. Results Here, an unaccustomed and green methodology to metalize the polyacrylonitrile, PAN, surface is reported with the intention of fashioning of a stable fibrous structure and the best specifications. The in-situ metallization process is essentially based on a loading of various amount of silver nanoparticles, as MA NPs “MA NPs”, (1 wt%, 4 wt%, 7 wt% and 10 wt%), which prepared by ultrasound irradiation assisted with a little amount of a reducer system (hydrazine/NaOH), on the PAN surface. The physiochemical characterization of as-synthesized fibrous samples was consisted of two parts: (i) characterization of sample nature (utilizing of XRD and UV-Vis. techniques), (ii) the chemical structure/morphological characterization (utilizing FESEM, TEM and AFM techniques) with performing all relevant measurements. From crystalline and UV-Vis. assessments, the observed shift in the diffraction peaks towards lower angles and slight shifts in the absorption bands of PAN (1 0 0) in the 1AgPAN and 4AgPAN samples, containing smaller-sized nanoparticles, are overt results of an improvement in the crystalline traits of the parent matrix. The FT-IR data revealed the intensification and overlapping of the IR-bands “C= N, C≡ N, N-H, C=O and O-H” without band shifting for fibrous samples with low content of MA NPs (1AgPAN and 4AgPAN samples). The intercalation of the MA NPs between the chains of the molecular matrix and the strong interconnection/hydrogen bonds between both components explain not only the change of the crystalline properties of the crystalline matrix but also the homogeneous distribution and creation of a stable layer of the MA NPs on the 0AgPAN surface, confirmed by the FESEM and TEM images. The results of the study of mechanical properties showed that the loading of small spherical particles onto the polymeric matric, in particular 1AgPAN and 4AgPAN samples, was positively reflected on the improvement of the mechanical performances and the related values, not in the 7AgPAN and 10AgPAN samples. Because the MA NPs have a hydrophobic character, loading them onto the bare polymeric fiber surface made the metalized fibers a stronger hydrophobic than that of hydrophilic character, which is consistent with differences in surface roughness (increasing Ra values). The main focus of this paper was to study the synergy of structural properties with each other. So, the results of the synergistic relationship study showed that the low amount of the MA NPs led to a comprehensive and positive correlation between all structural properties and in turn affected the mechanical properties-hydrophobic/hydrophilic properties. Noting that the fibers of the 1AgPAN and 4AgPAN samples had the best structural stability, compared to the fibers of the 0AgPAN, 7AgPAN and 10AgPAN samples, when they were: decreasing in Z value, increasing fiber diameter/particle size “P.S.”, increasing RCR and C.D. values and decreasing D.D, alteration in values obtained of the mechanical behavior and the increasing of contact angle “CA” values for water “H2O” droplets and decreasing for ethylene glycol “EG”. As a final result, the changes observed in the aforementioned measurements were reasonably regular and gradual for fibers with low MA NPs content, while the same measurements were significantly deteriorated in the case of fibers with higher MA NPs contents.

Growth performance, antibody response, and mammary gland development in New Zealand dairy replacement bovine heifers fed low or high amounts of unpasteurized whole milk.

This study evaluated the influence of feeding low and high preweaning allowances of unpasteurized whole milk (MA) on intake, selected blood metabolites, antibody response, mammary gland growth, and growth of New Zealand (NZ) dairy heifers to 7 mo of age. At 10 ± 2 d of age (study day 0), group-housed (six·pen-1) heifer calves (Holstein-Friesian × Jersey) were allocated to low (4 L whole milk·calf-1·d-1; n = 7 pens) or high (8 L whole milk·calf-1·d-1; n = 7 pens) MA for the next 63 d. Calves were gradually weaned between days 63 ± 2 and 73 ± 2. Calves in each pen had ad-libitum access to clean water, pelleted calf starter, and chopped grass hay from day 1 to 91 ± 2 d. At 92 ± 2 d, all calves were transferred to pasture, grazed in a mob, and their growth and selected blood metabolites were measured until day 209. All animals were weighed weekly during the indoor period (to day 91) and then at days 105, 112, 128, 162, 184, and 209. Skeletal growth measurements and blood samples to analyze selected metabolites were collected at the start of the experiment, weaning, and then postweaning on day 91, and day 201. Specific antibodies against Leptospira and Clostridia were quantified in weeks 7, 13, and 27. Mammary glands were scanned using ultrasonography at the start of the experiment, weaning, and day 201. Feeding high vs. low amounts of MA increased the preweaning growth in heifer calves (P = 0.02) without negatively affecting postweaning average daily gain (ADG) (P = 0.74). Compared with heifers fed with low MA, high MA fed heifers had a greater increase in antibodies against Leptospira and Clostridia by 13 wk of age (P = 0.0007 and P = 0.06, respectively). By 27 wk of age, the antibody response was the same in heifers offered low or high MA. There was no effect of MA on the total size of the mammary gland, measured by ultrasonography, at weaning and 7 mo of age. However, the greater MA was associated with more mammary parenchyma (P = 0.01) and less mammary fat pad (P = 0.03) in back glands at 7 mo of age compared with heifers fed lower MA. In conclusion, feeding a high vs. a low amount of unpasteurized whole milk increased the preweaning growth of New Zealand replacement heifers without negatively affecting their ADG during postweaning under grazing conditions. Feeding more (8 vs. 4 L·d-1) unpasteurized whole milk positively affected antibody responses early in life and mammary gland composition by 7 mo of age in dairy heifers reared for pasture-based dairy systems.

Abstract 3221: Differences in body composition among rectal cancer patients with neo-adjuvant treatment-related toxicity: Results from the ColoCare Study

Abstract BACKGROUND Neo-adjuvant chemoradiation is standard of care for patients diagnosed with stage II and III rectal cancer. This treatment can cause significant toxicities and may require treatment modifications. Obesity and low muscle mass (=sarcopenia) may portend increased toxicity to chemotherapy and/or radiation and may further affect mortality in rectal patients. The present study investigates associations of pre-treatment body composition parameters with toxicity in prospectively followed rectal cancer patients. METHODS This initial analysis includes data from n=320 stage II and III rectal cancer patients from four study sites of the ColoCare Study. All patients underwent neo-adjuvant treatment. Pre-treatment CT scans were semi-automatically segmented at spinal level L3 vertebrae using SliceOmatic + ABACS software v5.0 rev13 to quantify: subcutaneous and visceral fat area (SFA/VFA, cm2) and skeletal muscle area (SMA, cm2). Information on toxicities was abstracted from medical charts and categorized into gastrointestinal, cardiovascular, and other system-specific toxicities. Median values were calculated for continuous variables (e.g., age at diagnosis, VFA, SFA, and SMA) and compared among patients who did versus did not experience toxicities. Frequencies and percentages were calculated for categorical variables. RESULTS Among n=320 rectal cancer patients, n=48 (15%) patients experienced at least one toxicity that required treatment modification (defined as dose reduction or discontinuation of therapy). Patients who experienced toxicities were older (58 years vs 56 years), more likely to be male (63% vs 59%), and more likely to be diagnosed with stage III cancer (92% vs 69%) compared to patients who did not experience toxicities. Patients who had higher VFA (166 cm2 vs 148 cm2), lower SFA (197 cm2 vs 208 cm2), and lower SMA (144 cm2 vs 147 cm2) were more likely to experience toxicities compared to patients with lower VFA, higher SFA, or higher SMA. CONCLUSIONS Body composition parameters may differ between rectal cancer patients who experience toxicities versus those who do not. Multivariate logistic regression and Cox proportional hazard analyses are underway to investigate in more detail the associations of body composition parameters (VFA, SFA, SMA), sarcopenia, and sarcopenic obesity with toxicity and survival in rectal cancer patients. Citation Format: Jennifer Ose, Jeffrey T. Yap, Daniel Jeong, Simon Ta Van, Matthew F. Covington, Biljana Gigic, Johanna Nattenmueller, Benjamin Haaland, Tengda Lin, Sheetal Hardikar, Caroline Himbert, Anita R. Peoples, Anjelica Ashworth, Juergen Boehm, Petra Schrotz-King, Jane C. Figueiredo, Adetunji T. Toriola, Erin M. Siegel, Christopher I. Li, Alexis B. Ulrich, Martin Schneider, Hans-Ulrich Kauczor, David Shibata, Cornelia M. Ulrich. Differences in body composition among rectal cancer patients with neo-adjuvant treatment-related toxicity: Results from the ColoCare Study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3221.

Mechanisms of the destabilized Mach reflection of inviscid oblique detonation waves before an expansion corner

The stabilization of oblique detonation waves (ODWs) in an engine combustor is important for the successful applications of oblique detonation engines, and comprehensively understanding the effects of the inviscid reflection of ODWs on their stabilization and the relevant mechanisms is imperative to overall combustor design. In this study, the flow fields of ODW reflections in a space-confined combustor are numerically studied by solving the two-dimensional time-dependent multispecies Euler equations in combination with a detailed hydrogen combustion mechanism. The inviscid Mach reflections of ODWs before an expansion corner are emphasized with different flight Mach numbers, Ma, and different dimensionless reflection locations, ζ ≥ 0 (ζ = 0: the ODW reflects precisely at the expansion corner; ζ &gt; 0: the ODW reflects off the wall before the expansion corner). Two kinds of destabilization phenomena of the inviscid Mach reflection of an ODW induced by different mechanisms are found, namely wave-induced destabilization at large ζ &gt; 0 for moderate (not very low) Ma and inherent destabilization at any ζ &gt; 0 for low Ma. Wave-induced destabilization is attributed to the incompatibility between the pressure ratio across the Mach stem and its relative propagation speed, which is triggered by the action of the secondary reflected shock wave or the transmitted Mach stem on the subsonic zone behind the Mach stem. Inherent destabilization is demonstrated through an in-depth theoretical analysis and is attributed to geometric choking of the flow behind the Mach stem.

The vexing triad of obesity, alcohol, and coagulopathy predicts the need for multiple operations in liver transplantation

IntroductionOne in four liver transplants (LT) require return to the operating room(R-OR) within 48 h of surgery. We hypothesize that donor, recipient, and intraoperative factors will predict R-OR. MethodsLT recipients were enrolled in an observational study to measure coagulation with thrombelastography (TEG) were assessed with transplant recipient and donor variables for risk of R-OR. Results160 recipients with a median age of 55 years and a MELD-Na of 22 were analyzed. R-OR occurred in 22%. Recipient BMI (p = 0.006), donor heavy alcohol use (p = 0.017), TEG MA (p = 0.013) during the anhepatic phase of surgery, TEG MA at anhepatic and 30-min after reperfusion (p < 0.05), and red blood cell transfusions (p < 0.001) were associated with R-OR. ConclusionThe vexing triad of recipient obesity, heavy donor alcohol use, and low TEG MA were associated with a high rate of R-OR. Strategies to reduce this sub-optimal combination of risk factors could reduce the frequency of unplanned re-operations.

Trading strategy based on investment diversification technical analysis model

This paper takes gold and bitcoin as research objects and develops a model for traders. In this period, we established a multivariate quantitative technical analysis model of investment, selected 6 technical indicators with low correlation MA, MACD, BOLL, RSI, KDJ and Stoch RSI as evaluation indicators of trading intentions, and used the fuzzy evaluation model to combine the trading intentions of the 6 indicators to obtain the final daily trading intentions score. Combined with the trading intention score and risk tolerance coefficient of the day to adjust the asset allocation, the investment trading model proposed in this paper can provide support for relevant practitioners and has practical application significance.

Why take the square root? An assessment of interstellar magnetic field strength estimation methods

Context. The magnetic field strength in interstellar clouds can be estimated indirectly from measurements of dust polarization by assuming that turbulent kinetic energy is comparable to the fluctuating magnetic energy, and using the spread of polarization angles to estimate the latter. The method developed by Davis (1951, Phys. Rev., 81, 890) and by Chandrasekhar and Fermi (1953, ApJ, 118, 1137) (DCF) assumes that incompressible magnetohydrodynamic (MHD) fluctuations induce the observed dispersion of polarization angles, deriving B ∝ 1∕δθ (or, equivalently, δθ ∝ MA, in terms of the Alfvénic Mach number). However, observations show that the interstellar medium is highly compressible. Recently, two of us (ST) relaxed the incompressibility assumption and derived instead B ∝ 1/√δθ (equivalently, δθ ∝ MA2). Aims. We explored what the correct scaling is in compressible and magnetized turbulence through theoretical arguments, and tested the assumptions and the accuracy of the two methods with numerical simulations. Methods. We used 26 magnetized, isothermal, ideal-MHD numerical simulations without self-gravity and with different types of forcing. The range of MA and sonic Mach numbers Ms explored are 0.1 ≤ MA ≤ 2.0 and 0.5 ≤ Ms ≤ 20. We created synthetic polarization maps and tested the assumptions and accuracy of the two methods. Results. The synthetic data have a remarkable consistency with the δθ ∝ MA2 scaling, which is inferred by ST, while the DCF scaling failed to follow the data. Similarly, the assumption of ST that the turbulent kinetic energy is comparable to the root-mean-square (rms) of the coupling term of the magnetic energy between the mean and fluctuating magnetic field is valid within a factor of two for all MA (with the exception of solenoidally driven simulations at high MA, where the assumption fails by a factor of 10). In contrast, the assumption of DCF that the turbulent kinetic energy is comparable to the rms of the second-order fluctuating magnetic field term fails by factors of several to hundreds for sub-Alfvénic simulations. The ST method shows an accuracy better than 50% over the entire range of MA explored; DCF performs adequately only in the range of MA for which it has been optimized through the use of a “fudge factor”. For low MA, it is inaccurate by factors of tens, since it omits the magnetic energy coupling term, which is of first order and corresponds to compressible modes. We found no dependence of the accuracy of the two methods on Ms. Conclusions. The assumptions of the ST method reflect better the physical reality in clouds with compressible and magnetized turbulence, and for this reason the method provides a much better estimate of the magnetic field strength over the DCF method. Even in super-Alfvénic cases where DCF might outperform ST, the ST method still provides an adequate estimate of the magnetic field strength, while the reverse is not true.

Unraveling the hysteretic behavior at double cations-double halides perovskite - electrode interfaces

Despite over a decade of research on metal halide perovskites (MHPs) in the context of photovoltaic applications, understanding the nature of electronic and ionic processes associated with current-voltage (I-V) hysteretic behavior has been limited. Here, we explore the hysteretic behavior in (FAPbI3)0.85(MAPbBr3)0.15 perovskite devices with lateral Cr electrodes by applying first order reversal curve (FORC) bias waveform in I-V, Kelvin probe force microscopy (KPFM) measurements, and in-situ chemical imaging by time-resolved time-of-flight secondary ion mass spectrometry (tr-ToF-SIMS). In dark, we reveal pronounced hysteretic behaviors of charge dynamics in the off-field by probing time-dependent current and contact potential difference (CPD). Under illumination, transient and hysteretic behaviors are significantly reduced. The tr-ToF-SIMS results reveal that the hysteretic behaviors are strongly associated with accumulation of Br- ions at the interfaces. In addition, the low mobility MA+ ions result in transient behavior and contribute to the hysteretic phenomena. It was shown that Pb2+ ions can be reduced at the interfaces due to electrochemical reactions with the electrode in the presence of charge injection and photogenerated charges. These hysteretic behaviors associated with charge dynamics, ion migration, and interfacial electrochemical reaction are critical to further improve the performance and stability of MHPs photovoltaics and optoelectronics.

The reliability of low-dose chest CT for the initial imaging of COVID-19: comparison of structured findings, categorical diagnoses and dose levels.

The widespread use of computed tomography (CT) in COVID-19 may cause adverse biological effects. Many recommend to minimize radiation dose while maintaining diagnostic quality. This study was designed to evaluate the difference between findings of COVID-19 pneumonia on standard and low-dose protocols to provide data on the utility of the latter during initial imaging of COVID-19. Patients suspected of having COVID-19 were scanned with a 128-slices scanner using two consecutive protocols in the same session (standard-dose scan: 120 kV and 300 mA; low-dose scan: 80 kV and 40 mA). Dose data acquisition and analysis was performed using an automated software. High and low-dose examinations were anonymized, shuffled and read by two radiologist with consensus according to a highly structured reporting format that was primarily based on the consensus statement of the RSNA. Accordingly, 8 typical, 2 indeterminate, and 7 atypical findings were investigated. Cases were then assigned to one of the categories: (i) Cov19Typ, typical COVID-19; (ii) Cov19Ind, indeterminate COVID-19; (iii) Cov19Aty, atypical COVID-19; (iv) Cov19Neg, not COVID-19. McNemar test was used to analyze the number of disagreements between standard and low-dose scans regarding paired proportions of structured findings. Inter- test reliability was tested using kappa coefficient. The study included 740 patients with a mean age of 44.05±16.59 years. The median (minimum-maximum) dose level for standard protocol was 189.98 mGy•cm (98.20-493.54 mGy•cm) and for low-dose protocol was 15.59 mGy•cm (11.59-32.37 mGy•cm) differing by -80 and -254 mGy•cm from pan-European diagnostic reference levels. Only two findings for typical, one finding for indeterminate, and three findings for atypical categories were statistically similar (p > 0.05). The difference in other categories resulted in significantly different final diagnosis for COVID-19 (p < 0.001). Overall, 626 patients received matching diagnoses with the two protocols. According to intertest reliability analysis, kappa value was found to be 0.669 (p < 0.001) to indicate substantial match. CT with standard-dose had a sensitivity of 94% and a specificity of 72%, while CT with low-dose had a sensitivity of 90% and a specificity of 81%. Low kV and mA scans, as used in this study according to scanner manufacturer's global recommendations, may significantly lower exposure levels. However, these scans are significantly inferior in the detection of several individual CT findings of COVID-19 pneumonia, particularly the ones with GGO. Therefore, they should not be used as the protocol of choice in the initial imaging of COVID-19 patients during which higher sensitivity is required.