Figuring Out Gas & Galaxies In Enzo (FOGGIE). V. The Virial Temperature Does Not Describe Gas in a Virialized Galaxy Halo

The classical definition of the virial temperature of a galaxy halo excludes a fundamental contribution to the energy partition of the halo: the kinetic energy of nonthermal gas motions. Using simulations of low-redshift, ∼L* galaxies from the Figuring Out Gas & Galaxies In Enzo (FOGGIE) project that are optimized to resolve low-density gas, we show that the kinetic energy of nonthermal motions is roughly equal to the energy of thermal motions. The simulated FOGGIE halos have ∼2× lower bulk temperatures than expected from a classical virial equilibrium, owing to significant nonthermal kinetic energy that is formally excluded from the definition of T vir. We explicitly derive a modified virial temperature including nonthermal gas motions that provides a more accurate description of gas temperatures for simulated halos in virial equilibrium. Strong bursts of stellar feedback drive the simulated FOGGIE halos out of virial equilibrium, but the halo gas cannot be accurately described by the standard virial temperature even when in virial equilibrium. Compared to the standard virial temperature, the cooler modified virial temperature implies other effects on halo gas: (i) the thermal gas pressure is lower, (ii) radiative cooling is more efficient, (iii) O vi absorbing gas that traces the virial temperature may be prevalent in halos of a higher mass than expected, (iv) gas mass estimates from X-ray surface brightness profiles may be incorrect, and (v) turbulent motions make an important contribution to the energy balance of a galaxy halo.

Complexes of Li, Na and Mg with 2D Allotropies of Second and Third Period. A Theoretical Study

Complexes of Li, Na and Mg with graphene, silicene, phosphorene nanoflakes (NFs) and their 2D allotropies have been studied at dispersion corrected TPSS/def-TZVP level of theory. The energy partition analysis of the complexes revealed that for most of the complexes exchange and correlation energies represent dominant contributions to the binding with strong charge transfer from metal atom to a NF. The exceptions are Mg complexes of graphene and phosphorene NFs where binding is due to dispersion and correlation terms. This difference is also reflected in large Mg-NF distances suggesting weak intermolecular interactions in these complexes. The calculated activation energies for metal hopping are easily achievable at room temperatures for carbon and silicon allotropies. However, they are significantly higher for phosphorus allotropies reaching almost 18 kcal/mol. There is a reasonably good correlation between the activation energies for hopping and binding energies for graphene, silicene and phosphorene NFs. Such correlation is not observed however for graphene, silicene and phosphorene 2D allotropies

Forces and Specific Energy of Polyamide Grinding

This work investigated the grinding process of reinforced and nonreinforced polyamide materials using an Al2O3 grinding wheel. Samples were ground using a custom-made setup of sensors to evaluate in-line temperature, forces, and power. The surface roughness and images were acquired to assess the quality of the final products. The novelty of the work is to correlate the energy evaluation with the process efficiency during processing. Grinding at high cutting depths achieves good surface quality indicators, such as Ra < 5 μm and Rz < 5 μm. Results also reveal that special attention should be given to the infeed speed when cutting unfilled materials to produce good results. With high values of energy partition, the specific grinding energy stabilizes around 60 J/mm³. Strains must be applied quickly because, to ensure the unfilled materials respond better at this cutting depth, the reinforced materials suffer a slight degradation of quality.

The Dynamical Structure of a Warm Core Ring as Inferred from Glider Observations and Along-Track Altimetry

This study investigates the vertical structure of the dynamical properties of a warm-core ring in the Gulf of Mexico (Loop Current ring) using glider observations. We introduce a new method to correct the glider’s along-track coordinate, which is, in general, biased by the unsteady relative movements of the glider and the eddy, yielding large errors on horizontal derivatives. Here, we take advantage of the synopticity of satellite along-track altimetry to apply corrections on the glider’s position by matching in situ steric height with satellite-measured sea surface height. This relocation method allows recovering the eddy’s azimuthal symmetry, precisely estimating the rotation axis position, and computing reliable horizontal derivatives. It is shown to be particularly appropriate to compute the eddy’s cyclo-geostrophic velocity, relative vorticity, and shear strain, which are otherwise out of reach when using the glider’s raw traveled distance as a horizontal coordinate. The Ertel potential vorticity (PV) structure of the warm core ring is studied in details, and we show that the PV anomaly is entirely controlled by vortex stretching. Sign reversal of the PV gradient across the water column suggests that the ring might be baroclinically unstable. The PV gradient is also largely controlled by gradients of the vortex stretching term. We also show that the ring’s total energy partition is strongly skewed, with available potential energy being 3 times larger than kinetic energy. The possible impact of this energy partition on the Loop Current rings longevity is also discussed.

Energy Absorption in Actual Tractor Rollovers with Different Tire Configurations

In order to better understand the complexities of modern tractor rollover, this paper investigates the energy absorbed by a Roll-Over Protective Structure (ROPS) cab during controlled lateral rollover testing carried out on a modern narrow-track tractor with a silent-block suspended ROPS cab. To investigate how different tractor set-ups may influence ROPS and energy partitioning, tests were conducted with two different wheel configurations, wide (equivalent to normal ‘open field’ operation) and narrow (equivalent to ‘orchard/vineyard’ operation), and refer to both the width of the tires and the corresponding track. Dynamic load cells and displacement transducers located at the ROPS-ground impact points provided a direct measurement of the energy absorbed by the ROPS cab frame. A trilateration method was developed and mounted onboard to measure load cell trajectory with respect to the cab floor in real-time. The associated video record of each rollover event provided further information and opportunity to explain the acquired data. The narrow tire configuration consistently subjected the ROPS cab frame to more energy than the wide tire arrangement. To better evaluate the influence of the ROPS cab silent-blocks in lateral rollover, static and dynamic tests were performed. The results confirm that tires influence the energy partition significantly and that further understanding of silent-blocks’ dynamic performance is warranted.

Associations of Nutrient Intakes in Childhood With Hepatic and Abdominal Fat in Adolescence: The EPOCH Study

Objectives Body fat distribution is a strong risk factor for metabolic dysfunction in childhood and may be a target for lifestyle interventions. Prospective studies linking childhood dietary intake and future body fat deposition are needed to develop optimal therapeutic strategies. Our objective was to examine associations of childhood nutrient intakes with hepatic fat (HF), abdominal visceral (VAT) and subcutaneous adipose tissue (SAT) in adolescence. Methods Data were from 302 participants in the Exploring Perinatal Outcomes among Children (EPOCH) study in Colorado. Visits were completed in childhood (T1, ∼10yrs) and adolescence (T2, ∼16yrs). Diet was assessed by Block Kids Food Questionnaire at T1. HF (%) and abdominal SAT and VAT (mm2) were assessed by magnetic resonance imaging at T1 (abdominal fats only) and T2. Two types of models (energy partition and isocaloric substitution) were constructed to examine associations of nutrient intakes at T1 with HF and abdominal VAT and SAT at T2. Results In energy partition models adjusted for other macronutrients and confounders (sex, age, race/ethnicity, puberty), higher starch and total fat intake at T1 were associated with higher log-HF and SAT, respectively, at T2 [β (95% CI) = 0.07 (0.01,0.14) for log-HF per 100 kcal/d starch, 17.0 mm2 (4.3,29.7) for SAT per 100 kcal/d fat]. In isocaloric substitution models holding total energy intake (TEI) constant, replacing protein with starch was marginally associated with log-HF at T2 [0.12 (−0.02,0.26) per 5% TEI/d starch at the expense of protein], and replacing carbohydrates (CHO) with total fat was associated with SAT at T2 [19.3 mm2 (3.1,35.5) per 5% TEI/d fat at the expense of CHO]. There were no associations of nutrient intakes with VAT at T2. Adjusting for abdominal SAT at T1 attenuated associations between fat intake at T1 and SAT at T2 to the null [4.6 mm2 (−3.7,12.9) in energy partition models; 10.5 mm2 (−0.01,21.0) in isocaloric substitution models with CHO]. Conclusions Our results suggest that higher starch intake in childhood, especially at the expense of protein, is associated with higher adolescent HF. We also found that higher fat intake in childhood, especially at the expense of CHO, was associated with higher adolescent abdominal SAT, and that this may reflect an association that was already present earlier in childhood. Funding Sources NIDDK; NIH/NCATS Colorado CTSA.