Abstract Accretion rates ( M ̇ ) of young stars show a strong correlation with object mass ( M ); however, extension of the M ̇ – M relation into the substellar regime is less certain. Here, we ...present the Comprehensive Archive of Substellar and Planetary Accretion Rates (CASPAR), the largest compilation to date of substellar accretion diagnostics. CASPAR includes: 658 stars, 130 brown dwarfs, and 10 bound planetary mass companions. In this work, we investigate the contribution of methodological systematics to scatter in the M ̇ – M relation and compare brown dwarfs to stars. In our analysis, we rederive all quantities using self-consistent models, distances, and empirical line flux to accretion luminosity scaling relations to reduce methodological systematics. This treatment decreases the original 1 σ scatter in the log M ̇ – log M relation by ∼17%, suggesting that it makes only a small contribution to the dispersion. The CASPAR rederived values are best fit by M ̇ ∝ M 2.02 ± 0.06 from 10 M J to 2 M ⊙ , confirming previous results. However, we argue that the brown-dwarf and stellar populations are better described separately and by accounting for both mass and age. Therefore, we derive separate age-dependent M ̇ – M relations for these regions and find a steepening in the brown-dwarf M ̇ – M slope with age. Within this mass regime, the scatter decreases from 1.36 dex to 0.94 dex, a change of ∼44%. This result highlights the significant role that evolution plays in the overall spread of accretion rates, and suggests that brown dwarfs evolve faster than stars, potentially as a result of different accretion mechanisms.
Eurofer97 steel, a candidate structural material for future fusion reactors, was examined following 1.9 MeV proton-irradiation up to 0.91(5) dpa at 450 ∘C with and without a prior post-weld ...heat-treatment at 760 ∘C for 4 hours in a laser-welded state. A nanoindentation study found a pile-up-corrected nanohardness of 4.0(4) GPa in the as-welded fusion zone, decreasing to 2.1(3) GPa in the parent material. Irradiation temperature and post-weld heat treatment were both found to have a recovery effect on weld hardness, with the latter being entire. Proton-irradiation damage was not found to contribute to nanohardness at the temperature investigated. X-ray diffraction analysis found increased 1-dimensional dislocation density in the as-welded fusion zone, diminishing to 3(2) – 19.2(1.4)×1014 cm−2 in the parent material, dependent on irradiation and heat-treatment. Transient grating spectroscopy of Eurofer97 was attempted, finding a systematic underestimation of thermal diffusivity of average 15.6% from room-temperature to 600 ∘C when compared to laser flash analysis. Transient grating spectroscopy was, nevertheless, applied determining a room-temperature thermal diffusivity of 7.8(3) mm2 s−1 in the parent material and 6.7(4) mm2 s−1 in the as-welded fusion zone. Irradiation at 450 ∘C alleviated this difference in thermal diffusivity; recovery of weld-induced changes was observed up to 20% in the fusion zone due to irradiation conditions, distinct from temperature effects alone. Such results bode well for Eurofer97's application in fusion reactors, where welding will be essential. Thermal diffusivity has also been mapped at a fine scale across a heterogeneous structure, a technique applicable widely outside the realm of radiation materials science.
The natural history of great toe amputations Murdoch, Doug P.; Armstrong, David G.; Dacus, Joel B. ...
The Journal of foot and ankle surgery,
1997 May-Jun, Letnik:
36, Številka:
3
Journal Article
Recenzirano
The purpose of this study is to report the prevalence of reamputation following resection of the great toe and first ray in adults with diabetes. We abstracted the medical records of 90 diabetic ...great-toe and first-ray amputees admitted between 1981 and 1991. The most common etiologies of initial amputations were ulcer with son tissue infection (39%), ulcer with osteomyelitis (32%), and puncture wounds (12%). Sixty percent of all patients had a second amputation, 21% had a third, and 7% had a fourth. Fifteen percent of the patients who had a second amputation had it contralaterally. Seventeen percent subsequently underwent a below-knee amputation and 11% had a Transmetatarsal amputation on the same extremity, 3% had a below-knee amputation, and 2% a transmetatarsal amputation contralaterally. The mean time from the first to the second amputation was approximately 10 months.
The results of this study suggest that a large proportion of patients undergoing an amputation at the level of the great toe or first ray have subsequent amputations in the first year following the initial procedure. Additionally, it appears that the contralateral foot may be at significant risk for distal amputation following resection of the hallux or first ray.
Accretion rates (\(\dot{M}\)) of young stars show a strong correlation with object mass (\(M\)); however, extension of the \(\dot{M}-M\) relation into the substellar regime is less certain. Here, we ...present the Comprehensive Archive of Substellar and Planetary Accretion Rates (CASPAR), the largest to-date compilation of substellar accretion diagnostics. CASPAR includes: 658 stars, 130 brown dwarfs, and 10 bound planetary mass companions. In this work, we investigate the contribution of methodological systematics to scatter in the \(\dot{M}-M\) relation, and compare brown dwarfs to stars. In our analysis, we rederive all quantities using self-consistent models, distances, and empirical line flux to accretion luminosity scaling relations to reduce methodological systematics. This treatment decreases the original \(1\sigma\) scatter in the \(\log \dot{M}-\log M\) relation by \(\sim17\)%, suggesting that it makes only a small contribution to the dispersion. CASPAR rederived values are best fit by \(\dot{M}\propto M^{2.02\pm0.06}\) from 10~\(M_\mathrm{J}\) to 2~\(M_\odot\), confirming previous results. However, we argue that the brown dwarf and stellar populations are better described separately and by accounting for both mass and age. Therefore, we derive separate age-dependent \(\dot{M}-M\) relations for these regions, and find a steepening in the brown dwarf \(\dot{M}-M\) slope with age. Within this mass regime, the scatter decreases from 1.36 dex to 0.94 dex, a change of \(\sim\)44%. This result highlights the significant role that evolution plays in the overall spread of accretion rates, and suggests that brown dwarfs evolve faster than stars, potentially as a result of different accretion mechanisms.
The authors discuss the use of computers in medicine. A patient presenting with a condition requiring surgery is represented by a data file in a computer program. The user obtains data from the file ...by selecting items from a menu. Data are presented on the screen in pop-up windows. By examining the data and making judgments, the user may determine the pathology and make first a provisional and then a definitive diagnosis.
Looping: Moving Up with the Class Little, Thomas S; Dacus, Nannette B
Educational Leadership,
09/1999, Letnik:
57, Številka:
1
Magazine Article, Trade Publication Article
A Tennessee elementary school's adoption of a looping program, allowing teachers to stay with their classes for two years, resulted in improved student confidence and teacher/parent relationships. ...Looping places less pressure on young students to learn all curriculum objectives in one year. Lessons and benefits are summarized. (MLH)
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Selection in male cervids should optimize allocation of nutritional resources to the competing demands of body growth versus weapon development. We investigated allocation decisions of growing and ...mature male white-tailed deer (Odocoileus virginianus (Zimmerman, 1780)) from three regions of low, moderate, and high diet quality. We tested (i) if deer under greater nutritional limitations would allocate proportionally less to antler growth, (ii) if antler and body mass became less variable with age, and (iii) if antler size consistently exhibited positive allometry with body mass across age classes and nutritional planes. Greater nutrition increased antler allocation in 2.5 to 4.5 year olds but not in yearlings or prime-aged males. Variability of antler mass decreased with age and was generally less in more fertile regions, but body mass was equally variable across all ages and regions. Antler mass was positively allometric with body mass for all combinations of age class and region but exhibited age- and region-related differences. Our results suggest that accruing body mass is more important to lifetime reproductive success than increasing weapon size. Reduced allometric coefficients in older males likely stem from increasing use of skeletal mineral reserves, selective pressures favoring greater body mass, and possible selection for optimal weapon strength and structure.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Artificial antigen‐presenting cells (aAPCs) are currently used to manufacture T cells for adoptive therapy in cancer treatment, but a readily tunable and modular system can enable both rapid T cell ...expansion and control over T cell phenotype. Here, it is shown that microgels with tailored surface biochemical properties can serve as aAPCs to mediate T cell activation and expansion. Surface functionalization of microgels is achieved via layer‐by‐layer coating using oppositely charged polymers, forming a thin but dense polymer layer on the surface. This facile and versatile approach is compatible with a variety of coating polymers and allows efficient and flexible surface‐specific conjugation of defined peptides or proteins. The authors demonstrate that tethering appropriate stimulatory ligands on the microgel surface efficiently activates T cells for polyclonal and antigen‐specific expansion. The expansion, phenotype, and functional outcome of primary mouse and human T cells can be regulated by modulating the concentration, ratio, and distribution of stimulatory ligands presented on microgel surfaces as well as the stiffness and viscoelasticity of the microgels.
Microgels are fabricated as artificial antigen‐presenting cells (aAPCs) to present stimulatory ligands specifically on the surface. Surface‐specific functionalization is achieved via layer‐by‐layer coatings, forming a thin but dense polymer layer on the surface. Microgels modified with appropriate ligands promote polyclonal and antigen‐specific T cell expansion and regulate T cell phenotype and function.
Four field flow modeling of forced convective boiling Strayer, T.D.; Burdick, G.M.; Dacus, R.W. ...
Nuclear engineering and design,
October 2020, 2020-10-00, 20201001, 2020-10-01, Letnik:
367, Številka:
C
Journal Article
Recenzirano
Odprti dostop
•A four field multiphase computational fluid dynamics method is demonstrated.•Four field multiphase simulations can predict data for a variety of test section parameters.•Four field multiphase ...simulations allow flow regimes to transition smoothly.•Regimes include subcooled nucleate boiling, transition flow, and annular flow.•Extensive closure relationships are required for four field multiphase simulations.
A two-phase, four-field computational fluid dynamics (CFD) model was implemented in ANSYS CFX and subsequent three-dimensional calculations were compared with experimental data collected from an R134a experimental test facility. These calculations considered the following four fields for mass, momentum, and energy continuity – continuous liquid, dispersed vapor (bubbles), continuous vapor, and dispersed liquid (droplets). This four-field approach enabled CFD calculations to transition smoothly between the flow regimes present in heated, multiphase flows without the use of a-priori heuristics or flow-regime mapping. Such flow regimes included subcooled nucleate boiling, transition flow, annular flow, and dryout in three dimensions. This two-fluid, four-field model and related closure relationships predicted a variety of experimental data for multiple combinations of inlet temperatures, pressures, test section powers, and inlet velocities in a vertically oriented R134a flow loop.
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