Effective Volume Research Articles

Relationship between regional volume changes and water diffusion in fixed marmoset brains: an in vivo and ex vivo comparison.

Ex vivo studies of the brain are often employed as experimental systems in neuroscience. In general, brains for ex vivo MRI studies are usually fixed with paraformaldehyde to preserve molecular structure and prevent tissue destruction during long-term storage. As a result, fixing brain tissue causes microstructural changes and a decrease in brain volume. Therefore, the purpose of this study was to investigate the regional effect of brain volume and microstructural changes on the restricted diffusion of water molecules in the common marmoset brain using in vivo and ex vivo brains from the same individual. We used 9.4T magnetic resonance imaging and also compared the T2-weighted images and diffusion-weighted imaging (DWI) data between in vivo and ex vivo brains to investigate changes in brain volume and diffusion of water molecules in 12 common marmosets. We compared fractional anisotropy, mean diffusivity, AD (axial diffusivity), and radial diffusivity values in white matter and gray matter between in vivo and ex vivo brains. We observed that AD showed the strongest correlation with regional volume changes in gray matter. The results showed a strong correlation between AD and changes in brain volume. By comparing the in vivo and ex vivo brains of the same individual, we identified significant correlations between the local effects of perfusion fixation on microstructural and volumetric changes of the brain and alterations in the restricted diffusion of water molecules within the brain. These findings provide valuable insights into the complex relationships between tissue fixation, brain structure, and water diffusion properties in the marmoset brain.

Does Trauma Center Volume Matter? An Analysis of Trauma Center Volume on Outcome Using the TQIP/NTDB Database

Background: Increasing trauma center admission volume is said to decrease mortality. Evidence supporting this position is dependent upon patient groups and the time period studied, and gaps remain. We evaluated the effect of annual volume of critically injured patients on hospital mortality, comparing two time periods. The effect of critically injured patient volume on risk-adjusted mortality was hypothesized to decrease over time. Methods: This was a retrospective cohort study comparing data from an early group (2007–2011) and late group (2017–2021) of the National Trauma Data Bank. Critically injured adults (ISS > 15) admitted to the intensive care unit (ICU) or operating room from the emergency department at Level I and II trauma centers were included. The outcome of interest was risk-adjusted mortality across quintiles of patient admission volume, modeled using mixed-effects generalized linear models. Results: In total, 802,824 patients were included, 321,209 and 481,615 in the early and late groups, respectively. In the early group, increased patient volume was associated with a decreased risk-adjusted odds of mortality. This association was not seen in the late group. The overall odds of mortality in the late group demonstrated decreased mortality over time (OR 0.84, p < 0.001). Conclusions: The annual volume of critically injured patients was associated with decreased odds of hospital mortality during 2007–2011, though this effect was no longer present in the 2017–2021 sample. The continued dissemination of the best practices is warranted to decrease mortality, regardless of the admission volume of critically injured patients.

Larger versus smaller red blood cell volume per transfusion in hospitalized adults, children, and preterm neonates.

This is a protocol for a Cochrane Review (intervention). The objectives are as follows: The objective of this review is to compare the effectiveness and safety of larger versus smaller RBC volume per transfusion for anemia in hospitalized adults, children, and preterm neonates.

Development of quantitative PET/MR imaging for measurements of hepatic portal vein input function: a phantom study

BackgroundAccurate pharmacokinetic modelling in PET necessitates measurements of an input function, which ideally is acquired non-invasively from image data. For hepatic pharmacokinetic modelling two input functions need to be considered, to account for the blood supply from the hepatic artery and portal vein. Image-derived measurements at the portal vein are challenging due to its small size and image artifacts caused by respiratory motion. In this work we seek to demonstrate, using phantom experiments, how a dedicated PET/MR protocol can tackle these challenges and potentially provide input function measurements of the portal vein in a clinical setup.MethodsA custom 3D printed PET/MR phantom was constructed to mimic the liver and portal vein. PET/MR acquisitions were made with emulated respiratory motion. The PET/MR imaging protocol consisted of high-resolution anatomical MR imaging of the portal vein, followed by a PET acquisition in parallel to a dedicated motion-tracking MR sequence. Motion tracking and deformation information were extracted from PET data and subsequently used in PET reconstruction to produce dynamic series of motion-free PET images. Anatomical MR images were used post PET reconstruction for partial volume correction of the input function measurements.ResultsReconstruction of dynamic PET data with motion-compensation provided nearly motion-free series of PET frame data, suitable for image derived input function measurements of the portal vein. After partial volume correction, the individual input function measurements were within a 16.1% error range from the true activity in the portal vein compartment at the time of PET acquisition.ConclusionThe proposed protocol demonstrates clinically feasible PET/MR imaging of the liver for pharmacokinetic studies with accurate quantification of the portal vein input function, including correction for respiratory motion and partial volume effects.

Charge State of Weak Polyelectrolyte Brushes Determines Salt-Dependent Swelling and Hysteretic Behavior.

We investigate the combined effects of ionizable monomer fraction f, pH, and monovalent salt concentration Cs on the swelling of weak polyelectrolyte brushes (PEBs) by using in situ ellipsometry. Our system consists of random copolymers of basic (2-(dimethylamino)ethyl acrylate, DMAEA) and neutral (2-hydroxyethyl acrylate, HEA) monomers at varying fractions of ionizable monomer. Swelling of the brushes qualitatively follows the trends predicted by scaling laws for PEBs under different charge states but quantitatively deviates at specific ionic strengths and pH values. We posit these deviations stem from the lack of excluded volume effects and assumptions of strong chain stretching in current theoretical models. Most notably, we uncover a salt-dependent, nonmonotonic hysteretic behavior as weak PEB brushes are cycled from protonated to deprotonated and back. The nonmonotonic trend of hysteresis with salt can be explained by an interplay between the protonation facilitating effects of salt in the osmotic regime and the charge screening effects in the salted regime, which make charge distribution along weak PEBs more uniform. Our results provide insight into the mechanisms that determine whether polyelectrolytes exhibit weak versus strong polyelectrolyte behavior in various environmental conditions.

The critical role of size effect on internal damage and mechanical properties of flax fiber reinforced composites

The effect of the size on the strength of laminated artificial fiber reinforced composites has been extensive discussed during the design of large composites structure. With the trial as the structures in aerospace, civil engineering, automobile industry, the scaling of the properties of plant fiber reinforced composite should be studied. In this paper, the size effect and failure mechanism of tensile and impact properties of flax fiber reinforced composites were valuated. The effects of different area, thickness and volume on the tensile properties of composites were explored. Additionally, the failure mechanism of size effect on tensile specimens was proposed through the damage morphologies of composites. It is found that the twist of fiber bundle plays an important role in the size effect of composite thickness. Besides, the relationship between impact properties and size effect of composites was conducted, including the size of hammer, different impact energy and sample size. The curves of different types of impact samples were normalized to verify the linear rule in response stage. The crack length after impact was measured and the size effect of crack length was discussed. The size effect of crack area was studied by calculating the crack area with ultrasonic C-scan. Different “size effects” between flax fibers and artificial fibers were explored. The results are expected to provide a theoretical basis for the structural design of plant fiber reinforced composites.

The Effects of money supply on Economic Growth of Laos

This research aims to analyze the effect of money supply volume on the economic growth of Lao PDR. Using secondary data annually from 2012–2022. which uses the multiple regression equation (multiple regression) with the method of least squares (OLS) to estimate the coefficients of dependent variables and independent variables, starting from checking the properties of the unit root data using the Augmented Dick Fuller test statistic method to test the data. Through checking the properties of the model of external factors that affect the amount of money supply (M2), it was found that the coefficient of decision Adjusted R Square = 0.9931, which means that the independent variables Gross National Income (GNI), Exchange Rate (Exr), and Consumer Price Index (CPI) can explain the variable according to the amount of money (M2) determined up to 99.31%; the rest depends on other factors that are not included in the study. Therefore, the model of external factors that affect the amount of money M2 can be used and depends on at least one factor identified. Also, by bringing the data to test the effect of the independent variable on the dependent variable in the long term and in the short term, ECM(-1) found that the model that simulates the effect of the amount of money M2 on the economic growth of the Lao PDR in the long-term equilibrium state (co-integration) and in the short-term equilibrium state (Error Correction Model: ECM) is not applicable and does not depend on the identified factors. But it will have a long-term effect, which, through checking the properties of the model from a long-term perspective, found that the coefficient of decision Adjusted R Square = 0.6877, which means that the independent variable M2 money can explain the variable according to the economic growth rate determined in the long term up to 68.77%. The change in the money M2 in the short term does not affect the economic growth rate of the Lao PDR, but the change in the money M2 in the long term will definitely affect the economic growth rate.

The Effect Of Surgeon Volume On Outcomes Following Total Shoulder Arthroplasty: A Nationwide Assessment

The Effect Of Surgeon Volume On Outcomes Following Total Shoulder Arthroplasty: A Nationwide Assessment

Economic impact case study of a wearable medical device for the diagnosis of obstructive sleep apnoea

BackgroundAcuPebble SA100 (‘AcuPebble’) is a novel wearable medical device to diagnose obstructive sleep apnoea (OSA). This paper investigates the potential economic impact of the technology in the UK through cost savings analysis, and the redirection of savings into further diagnoses.MethodsA cost comparison study was conducted, comparing AcuPebble to the standard diagnostic approach of home respiratory polygraphy (HRP) and in-clinic polysomnography (PSG), estimating the net benefit value (NBV) and return on investment (ROI). Cohort size was varied to model the effects of volume discounted pricing and staff training costs. To demonstrate the potential for cost savings, data on the healthcare costs of undiagnosed OSA patients were used to quantify the benefit of increased OSA diagnosis rates, as facilitated by AcuPebble.ResultsFor 500 uses of AcuPebble, the NBV in the diagnostic pathway over one year would be in excess of £101,169, increasing to £341,665 for 1,500 uses, £1,263,993 for 5,000 uses, and to £2,628,198 for 10,000 uses, with ROIs of 2.02, 3.03, 5.05, and 6.56, respectively. Given an initial cohort of 1,500 patients, 4,555 extra AcuPebble studies could be completed by redirecting resources from HRP/PSG. Direct cost savings to the NHS from resultant lower undiagnosed rates could be between £24,147 and £4,707,810, based on the cost per use and the percentage of tests that result in a positive diagnosis (varied from 25 to 75% positives).ConclusionsAcuPebble presents an opportunity for substantial healthcare savings, enabling an increase in the number of people tested, diagnosed and treated for OSA.

The GREENWATER study: patients' green sensitivity and potential recovery of injected contrast agents.

The environmental footprint of iodinated contrast agents (ICAs) and gadolinium-based contrast agents (GBCAs) is noteworthy. This study assesses: (1) patients' "green sensitivity" as measured by their acceptance in a sustainability study and (2) the resulting potential reduction of contrast residuals in wastewater. After ethical approval, participants scheduled for administration of ICAs or GBCAs for diagnostic purposes were enrolled in this prospective observational study from July 2022 to October 2023. They were asked to prolong their hospital stay by up to 60 min to collect their first urine in dedicated canisters, thereby measuring the recovery rates of ICAs and GBCAs as found/theoretical ratio of concentrations. Mann-Whitney U, χ2 tests, and multivariable regression analysis were used. Patients scheduled for contrast-enhanced CT or MRI (n = 455) were screened; 422 (92.7%) accepted to participate. We enrolled 212 patients administered with ICAs and 210 administered with GBCAs. The median recovery rate was 51.2% (interquartile range 29.2-77.9%) for ICAs and 12.9% (9.0-19.3%) for GBCAs. At multivariable analysis, a significant effect of patient age (ICAs, p = 0.001; GBCAs, p = 0.014), urine volume (p < 0.001 for both), and time interval from contrast administration to urine collection (p < 0.001 for both) on recovery rates was found for both contrast agents; injected contrast volume (p = 0.046) and saline flushing usage (p = 0.008) showed asignificant effect only for ICAs. The high patient enrollment compliance (93%) and potential recovery rates of 51% (ICAs) and 13% (GBCAs) play in favor of sustainable practices in reducing the environmental footprint of contrast agents. Question How many patients are willing to extend their stay in radiology by up to 60 min to help reduce the environmental impact of contrast agents? Findings Over 90% of screened patients agreed to extend their stay by up to 60 min and collect their urine in dedicated containers. Clinical relevance Patients demonstrated a high willingness to cooperate in reducing the environmental impact of contrast agents, allowing for a potential recovery of approximately 51% for iodinated and 13% for gadolinium-based contrast agents.

Radioresistance and brain metastases: a review of the literature and applied perspective

Intracranial metastatic disease is a serious complication of cancer, treated through surgery, radiation, and targeted therapies. The central role of radiation therapy makes understanding the radioresistance of metastases a priori a key interest for prognostication and therapeutic development. Although historically defined clinic-radiographically according to tumour response, developments in new techniques for delivering radiation treatment and understanding of radioprotective mechanisms led to a need to revisit the definition of radioresistance in the modern era. Factors influencing radioresistance include tumour-related factors (hypoxia, cancer stem cells, tumour kinetics, tumour microenvironment, metabolic alterations, tumour heterogeneity DNA damage repair, non-coding RNA, exosomes, methylomes, and autophagy), host-related factors (volume effect &amp;amp; dose-limiting non-cancerous tissue, pathophysiology, and exosomes), technical factors, and probabilistic factors (cell cycle and random gravity of DNA damage). Influences on radioresistance are introduced and discussed in the context of brain metastases.

Highly Conducting and Ultra-Stretchable Wearable Ionic Liquid-Free Transducer for Wireless Monitoring of Physical Motions.

Wearable strain transducers are poised to transform the field of healthcare owing to the promise of personalized devices capable of real-time collection of human physiological health indicators. For instance, monitoring patients' progress following injury and/or surgery during physiotherapy is crucial but rarely performed outside clinics. Herein, multifunctional liquid-free ionic elastomers are designed through the volume effect and the formation of dynamic hydrogen bond networks between polyvinyl alcohol (PVA) and weak acids (phosphoric acid, phytic acid, formic acid, citric acid). An ultra-stretchable (4600% strain), highly conducting (10 mScm-1), self-repairable (77% of initial strain), and adhesive ionic elastomer is obtained at high loadings of phytic acid (4:1 weight to PVA). Moreover, the elastomer displayed durable performances, with intact mechanical properties after a year of storage. The elastomer is used as a transducer to monitor human motions in a device comprising an ESP32-based development board. The device detected walking and/or running biomechanics and communicated motion-sensing data (i.e., amplitude, frequency) wirelessly. The reported technology can also be applied to other body parts to monitor recovery after injury and/or surgery and inform practitioners of motion biomechanics remotely and in real time to increase convalescence effectiveness, reduce clinic appointments, and prevent injuries.

Investor attention and market activity: evidence from green cryptocurrencies

Purpose This paper aims to investigate the relationship between investor attention and market activity (return, volatility and volume) using a sample of 14 clean energy cryptocurrencies (hereafter green cryptocurrency), namely, Chia, Cardano, Stellar, Tron, Ripple, Nano, IOTA, EOS, Bitcoin Green, Alogrand, Hedara, Polkadot, FLOW and Tezos. Design/methodology/approach This paper use 26040 crypto-day observations and a range of econometric techniques, including Dynamic Granger causality, Panel vector autoregression (VAR), Impulse response function and the decomposition of forecast error variance. Findings Based on 26040 crypto-day observations, this paper finds a bidirectional Granger causal relationship between investor attention and all measures of market activity, namely, return, absolute volatility, squared volatility and volume. The panel VAR and impulse response function demonstrate that market activity in the green crypto ecosystem, especially volatility and volume, is considerably responsive to changes in investor attention proxied by Google search volume (hereafter Google search volume (GSV)). The findings also demonstrate a significant asymmetric effect of return and volume on investor attention since past negative shocks “or bad news” in return and volume are more likely to grab the investor’s attention. All in all, our study emphasizes the crucial role of investor attention in the green crypto ecosystem. Originality/value (i) The research is the first to shed light on investor attention in the green cryptocurrency market. (ii) The paper uses a wide range of green cryptocurrencies to offer a comprehensive picture of the green cryptocurrency ecosystem. (iii) This paper is the first to use the panel Granger causality to investigate investor attention in the cryptocurrency market which provides several advantages over the conventional Granger causality approach. (iv) This paper is the first to provide novel empirical evidence on the prevalent influence of investor attention in the green crypto market.

Cardiac magnetic resonance characteristics of the athlete's heart: deeper insights into cardiac remodelling

Abstract Cardiac magnetic resonance (CMR) offers precise quantification for myocardial parameters. Understanding the effects of different training volumes on the athlete’s heart could be the key to distinguishing between cardiac conditions. This study aims to investigate CMR parameters including T1- and T2 mapping in healthy athletes and less active individuals and explore their relationship with training volumes in both sexes. We included healthy athletes (weekly training hours &amp;gt;7) and less active age- and sex-matched control individuals (weekly training hours ≤6), and performed CMR examinations. We assessed ventricular volumes, masses, and function, and conducted T1- and T2-mapping on non-contrast short-axis images. A total of 270 CMR examinations were conducted, comprising 185 athletes (119 males, mean age 22±6 years, weekly training hours: 19±7) and 85 controls (50 males, mean age 26±3 years, weekly training hours: 3±2). In male athletes compared to less active individuals, we observed pronounced signs of sports-related cardiac remodeling, including increased end-diastolic volume and mass index (Left ventricular end-diastolic volume index (LVEDVi): 120±16 vs 97±12 ml/m2, p&amp;lt;0.001; left ventricular mass index (LVMi): 70±14 vs 53±9 g/m2, p&amp;lt;0.001). Similarly, female athletes exhibited significant sports adaptations compared to controls (LVEDVi: 103±12 vs 86±11 ml/m2, p&amp;lt;0.001; LVMi: 54±9 vs 39±5 g/m2, p&amp;lt;0.001). T1-mapping values in athletes were lower than in the control group for both sexes (males: 939±25 vs 961±20 p&amp;lt;0.001, females: 966±21 vs 985±17, p&amp;lt;0.001). T1 values showed negative correlations with training hours (r=-0.362, p&amp;lt;0.001), LVEDVi (r=-0.411, p&amp;lt;0.001), and LVMi (r=-0.546, p&amp;lt;0.001). A significant association between T1 values and training hours persisted across various models. In the raw model, every additional training hour correlated with a T1 reduction of 0.946 ms (p&amp;lt;0.001). Adjusting for age, sex, and heart rate (HR) in model 2, the association remained significant, with each additional training hour corresponding to a T1 reduction of 0.825 ms (p&amp;lt;0.001). Further adjustments for LVMi in model 3 revealed a significant association, with a decrease of 0.565 ms in T1 values for each additional training hour (p=0.002). Among athletes, training years associated with decreased T1 and increased ventricular end-diastolic volumes and myocardial mass indices (LVEDVi: r=0,232, p=0,002; p&amp;lt;0,001; LVMi: r=0,279, p&amp;lt;0,001; T1-mapping: r=-0,169; p=0,026). Examining the differences between sexes we found that female athletes respond slightly less to a unit of exercise compared to males. Our findings underscore that different training hours and invested years have a meaningful impact on physiological adaptation. Female athletes’ heart responds slightly less to these effects. But in both sexes, higher training hours resulted in lower T1 and this relationship persisted independent of the influences of age, HR, and LVMi.

Physicochemical analysis on molecular interactions in binary liquid mixtures at various temperatures and correlation with the Jouyban–Acree model (3-pentanol with allyl amine, allyl alcohol, and allyl chloride)

ABSTRACT This study investigates the molecular interactions in binary mixtures of 3-pentanol with three allyl compounds (allyl amine, allyl alcohol, and allyl chloride) at various temperatures. The excess molar volume, excess isentropic compressibility, deviation in viscosity, and excess Gibbs free energy of activation of viscous flow were determined from measured values of densities, speeds of sound, and viscosities. The data were analysed to determine excess properties and deviations from ideal behaviour, highlighting the predominance of molecular interactions such as geometrical packing effects and free volume effects. The experimental results were correlated with the Jouyban−Acree model, which effectively relates the observed thermodynamic properties to the composition of the mixtures. This correlation allows for a deeper understanding of molecular interactions that influence the properties of these binary mixtures across different temperatures.

Effect of pre-chamber volume and nozzle number on turbulent jet combustion characteristics of GDI engines

There are few studies on the effect of turbulent jets on the combustion characteristics of passive pre-chamber (PC) gasoline engines, and their mechanism needs to be elucidated. Therefore, a 3-D simulation was performed using CONVERGE software. The results reveal that a modest expansion in the PC volume contributes to combustion due to the increased jet energy, but when it is too large, the above effect is weakened. In this study, at a smaller 0.8 ml volume, the combustion is still similar to traditional spark plug ignition. At middle 1.6 ml volume, the mixture concentration in the PC increases and the uniformity is better, resulting in the highest jet velocity and shortest jet duration, thus achieving the fastest flame propagation and the highest heat release rate (HRR). However, at a larger 1.8–2.0 ml volume, the mixture concentration near the spark-plug is sharply reduced, thus the reduced combustion rate in the PC leads to insufficient jet energy in the subsequent jets and resulting deterioration in combustion. An appropriate increase in nozzle number also improves combustion by introducing more ignition sources. But more nozzles not always improving the combustion. In the eight-nozzle case, three nozzles are close to the exhaust valve so that the intake is inhibited, resulting in a worsening of the ignition. The combustion under six-nozzle shows the highest HRR and shortest combustion duration. However, the combustion deteriorates at eight-nozzle, since the increase in the ignition point is not enough to compensate for the negative impact of the reduced jet intensity on combustion.

Optimal fluid resuscitation targets in septic patients with acutely decompensated heart failure

BackgroundTo determine the optimal fluid resuscitation volume in septic patients with acutely decompensated heart failure (ADHF).MethodsSeptic patients with ADHF were identified from a tertiary urban medical center. The generalized additive models were used to explore the association between fluid resuscitation volume and endpoints, and the initial 3 h fluid resuscitation volume was divided into four groups according to this model: < 10 mL/kg group, ≥ 10 to ≤ 15 mL/kg group, > 15 to ≤ 20 mL/kg group, and > 20 mL/kg group. Logistic and Cox regression models were employed to explore the association between resuscitation volume and primary endpoint, in-hospital mortality, as well as secondary endpoints including 30-day mortality, 1-year mortality, invasive ventilation, and ICU admission.ResultsA total of 598 septic patients with a well-documented history of HF were enrolled in the study; 405 patients (68.8%) had sepsis-induced hypoperfusion. Patients with NYHA functional class III and IV were 494 (83.9%) and 22 (3.74%), respectively. Resuscitation volumes above 20 mL/kg (OR 3.19, 95% CI 1.31–8.15) or below 10 mL/kg (OR 2.33, 95% CI 1.14–5.20) significantly increased the risk of in-hospital mortality in septic patients, while resuscitation volumes between 15 and 20 mL/kg were not associated with the risk of in-hospital death in septic patients (OR 1.79, 95% CI 0.68–4.81). In the multivariable Cox models, the effect of resuscitation volume on 30-day and 1-year mortality in septic patients was similar to the effect on in-hospital mortality. Resuscitation volume exceeds 15 mL/kg significantly increased the risk of tracheal intubation, while fluid resuscitation volume was not associated with ICU admission in the septic patients. In septic patients with hypoperfusion, these fluid resuscitation volumes have similar effects on patient outcomes. This association was consistent across the three subgroups with worsened cardiac function, as well as in sensitivity analyses.ConclusionsOur study observed that an initial fluid resuscitation volume of 10–15 mL/kg in the first 3 h was optimal for early resuscitation in septic patients with ADHF, particularly those with worsened cardiac function. These results need to be confirmed in randomized controlled trials with larger sample sizes.

Scale-Dependent Effects of Urban Canopy Cover, Canopy Volume, and Impervious Surfaces on Near-Surface Air Temperature in a Mid-Sized City

Cities are significantly warmer than their surrounding rural environments. Known as the ‘urban heat island effect’, it can affect the health of urban residents and lead to increased energy use, public health impacts, and damage to infrastructure. Although this effect is extensively researched, less is known about how landscape characteristics within cities affect local temperature variation. This study examined how tree canopy cover, canopy volume, and impervious surface cover affect daytime near-surface air temperature, and how these effects vary between different scales of analysis (10, 30, 60, 90 m radii), ranging from approximate street corridor to city block size. Temperature data were obtained from a car-mounted sensor, with traverse data points recorded during morning, afternoon, and evening times, plotted throughout the city of Portland, OR. The variability in near-surface air temperature was over 10° F during each traverse period. The results indicate that near-surface air temperature increased linearly with impervious surface cover and decreased linearly with tree canopy cover, with canopy volume reducing the temperature by 1° F for every 500 cubic feet of canopy volume for evening temperatures. The magnitude of the effect of tree canopy increased with spatial scale, with 60 and 90 m scales having the greatest measurable effect. Canopy volume had a positive relationship on presumed nighttime and early-morning temperatures at 60 and 90 m scales, potentially due to the impacts of wind fluctuation and air roughness. Canopy cover still contributed the largest overall decrease in street-scale temperatures. Increasing tree canopy cover and volume effectively explained the lower daytime and evening temperatures, while reducing impervious surface cover remains critical for reducing morning and presumed nighttime urban heat. The results may inform strategies for urban foresters and planners in managing urban land cover and tree planting patterns to build increased resiliency towards moderating urban temperature under warming climate conditions.

A Relaxation Scheme for the Simulation of Two‐Phase Flows With Inaccessible Pore Volume in Polymer Flooding

ABSTRACTThe simulation of polymer injection in a reservoir is of paramount importance in enhanced oil recovery. Despite decades of research, the computation of polymer flows in porous media remains a challenging task. The main difficulty lies in the necessity to take into account the effect of inaccessible pore volumes (IPV), for which standard closure laws give rise to a weakly hyperbolic or even non‐hyperbolic system. In the latter case, exponential instabilities may appear at the continuous level, which must be addressed at the discrete level so as to prevent a premature stop of the numerical simulations. The notion of IPV was introduced by engineers in order to account for the following observation: when a polymer solution is injected into an initial core saturated with water, the breakthrough of the polymer at the exit occurs before that of the water in which it is injected. It seems that due to their large size, the polymer molecules cannot insinuate themselves into all pores as well as water. Having less volume to flood, the polymer molecules see their speed increased, hence the ad hoc acceleration factor associated with the polymer. In this work, we propose a relaxation method that guarantees some practical robustness for all IPV laws. This is achieved by replacing the original system by a relaxation model which is always hyperbolic. The designed relaxation model involves two parameters which enable us not only to adjust the correct amount of numerical dissipation, but also to ensure positivity for some critical quantities such as water saturation and polymer concentration. Extensive numerical tests are performed in order to compare the relaxation scheme to the more classical upwind scheme for several IPV laws.

Genomic analysis of intracranial and subcortical brain volumes yields polygenic scores accounting for variation across ancestries.

Subcortical brain structures are involved in developmental, psychiatric and neurological disorders. Here we performed genome-wide association studies meta-analyses of intracranial and nine subcortical brain volumes (brainstem, caudate nucleus, putamen, hippocampus, globus pallidus, thalamus, nucleus accumbens, amygdala and the ventral diencephalon) in 74,898 participants of European ancestry. We identified 254 independent loci associated with these brain volumes, explaining up to 35% of phenotypic variance. We observed gene expression in specific neural cell types across differentiation time points, including genes involved in intracellular signaling and brain aging-related processes. Polygenic scores for brain volumes showed predictive ability when applied to individuals of diverse ancestries. We observed causal genetic effects of brain volumes with Parkinson's disease and attention-deficit/hyperactivity disorder. Findings implicate specific gene expression patterns in brain development and genetic variants in comorbid neuropsychiatric disorders, which could point to a brain substrate and region of action for risk genes implicated in brain diseases.