Brown Meets Green: Light and Nutrients Alter Detritivore Assimilation of Microbial Nutrients From Leaf Litter

In aquatic detrital-based food webs, research suggests that autotroph-heterotroph microbial interactions exert bottom-up controls on energy and nutrient transfer. To address this emerging topic, we investigated microbial responses to nutrient and light treatments during Liriodendron tulipifera litter decomposition and fed litter to the caddisfly larvae Pycnopsyche sp. We measured litter-associated algal, fungal, and bacterial biomass and production. Microbes were also labeled with 14C and 33P to trace distinct microbial carbon (C) and phosphorus (P) supporting Pycnopsyche assimilation and incorporation (growth). Litter-associated algal and fungal production rates additively increased with higher nutrient and light availability. Incorporation of microbial P did not differ across diets, except for higher incorporation efficiency of slower-turnover P on low-nutrient, shaded litter. On average, Pycnopsyche assimilated fungal C more efficiently than bacterial or algal C, and Pycnopsyche incorporated bacterial C more efficiently than algal or fungal C. Due to high litter fungal biomass, fungi supported 89.6–93.1% of Pycnopsyche C growth, compared to 0.2% to 3.6% supported by bacteria or algae. Overall, Pycnopsyche incorporated the most C in high nutrient and shaded litter. Our findings affirm others\u27 regarding autotroph-heterotroph microbial interactions and extend into the trophic transfer of microbial energy and nutrients through detrital food webs

Osteomalacia as a Late Metabolic Complication of Ifosfamide Chemotherapy in Young Adults: Illustrative Cases and Review of the Literature

Purpose. Ifosfamide is a drug commonly used in the management of sarcomas and other solid tumours. One potential toxicity of its use is renal tubular damage, which can lead to skeletal abnormalities; rickets in children and osteomalacia in adults. We aimed to characterise this rare complication in adults. Patients. Three illustrative patient cases treated in our institution are presented. All were treated for sarcoma, and received varying doses of ifosfamide during their therapy. Methods. We performed a review of the literature on the renal tubular and skeletal complications of ifosfamide in adults. Papers were identified by searches of PubMed using the terms “osteomalacia,” “nephrotoxicity,” “Fanconi syndrome,” “ifosfamide,” and “chemotherapy” for articles published between 1970 and 2006. Additional papers were identified from review of references of relevant articles. Results. There are only four case reports of skeletal toxicity secondary to ifosfamide in adults; the majority of data refer to children. Risk factors for development of renal tubular dysfunction and osteodystrophy include platinum chemotherapy, increasing cumulative ifosfamide dose, and reduced nephron mass. The natural history of ifosfamide-induced renal damage is variable, dysfunction may not become apparent until some months after treatment, and may improve or worsen with time. Discussion. Ifosfamide-induced osteomalacia is seldom described in adults. Clinicians should be vigilant for its development, as timely intervention may minimise complications

Diffusion measurements to understand dynamics and structuring in solutions involving a homologous series of ionic liquids

The self-diffusion coefficients of each of the components in mixtures containing pyridine and each of the homologous series 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imides in acetonitrile were determined using NMR diffusometry (i. e., Pulsed Gradient Spin Echo). The nature of solvation was found to change significantly with the proportion of salt in the mixtures. Increased diffusion coefficients (when corrected for viscosity) for the molecular components were observed with increasing proportion of ionic liquid and with increasing alkyl chain length on the cation. Comparison of the molecular solvents suggests increased interactions in solution of the pyridine with other components of the mixture, consistent with the proposed interactions shown previously to drive changes in reaction kinetics. Discontinuities were seen in the diffusion data for each species in solution across different ionic liquids between the hexyl and octyl derivatives, suggesting a change in the structuring in solution as the alkyl chain on the cation changes and demonstrating the importance of such when considering homologous series

3D Simulations of Betelgeuse's Bow Shock

Betelgeuse, the bright, cool red supergiant in Orion, is moving supersonically relative to the local interstellar medium. The star emits a powerful stellar wind which collides with this medium, forming a cometary structure, a bow shock, pointing in the direction of motion. We present the first 3D hydrodynamic simulations of the formation and evolution of Betelgeuse's bow shock. The models include realistic low temperature cooling and cover a range of plausible interstellar medium densities and stellar velocities between 0.3 - 1.9 cm-3 and 28 - 73 km/s. We show that the flow dynamics and morphology of the bow shock differ substantially due to the preferential growth of Rayleigh-Taylor or Kelvin-Helmholtz instabilities in the models. The former dominate the models with slow stellar velocities resulting in a clumpy bow shock sub-structure, whereas the latter produce a smoother, more layered sub-structure in the fast models. If the mass in the bow shock shell is low, as seems to be implied by the AKARI luminosities (~0.003 Msun), then Betelgeuse's bow shock is very young and is unlikely to have reached a steady state. The circular nature of the bow shock shell is consistent with this conclusion. Thus, our results suggest that Betelgeuse entered the red supergiant phase only recently.Comment: Minor revisions, replaced Fig. 1, 15, and 16, added movies. For a pdf version with higher resolution, see A&A: Forthcomin

Liver regeneration in dogs: Morphologic and chemical changes

Forty-four percent and 72% hepatectomy were carried out in dogs and the animals were sacrificed for biochemical and pathologic studies from 0.5 to 6 days later. Compensatory hypertrophy and hyperplasia ("regeneration") were evident within 1 day, reached a maximum in 3 days, and were almost complete by 6 days. Coincident with the histologic events of regeneration were decreases in responsiveness of receptor adenyl cyclase to glucagon stimulation, increases of cyclic AMP, inconsistent changes in plasma insulin, and increases in plasma glucagon. These studies have standardized hepatic resection in dogs and they have focused attention upon some possible mechanisms that will require further study. © 1978 Academic Press, Inc. All rights of reserved

Allergic Contact Dermatitis to Mastisol Adhesive Used for Skin Closure in Orthopedic Surgery: A Case Report

We report on a rare case of allergic contact dermatitis (ACD) from Mastisol liquid adhesive. We are aware of a few reports in the medical literature, but none describes an allergic reaction during the third exposure to the offending agent. Our patient was a 20-year-old Caucasian man with a history of cerebral palsy spastic hemiplegia who underwent single-event multilevel soft-tissue surgery to optimize function of his left upper extremity. He developed a severe cutaneous allergic reaction after his third exposure to Mastisol. He was subsequently admitted to the inpatient service and managed without further complications by a multidisciplinary team comprising orthopedics, pediatrics, and dermatology. We discuss the etiology, clinical features, diagnosis, and treatment of this entity, and we also review relevant available literature on the subject. We aim at creating further awareness of allergic reactions because of exposure to available skin-prepping and wound-dressing agents.Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Exploring 4D Quantum Hall Physics with a 2D Topological Charge Pump

The discovery of topological states of matter has profoundly augmented our understanding of phase transitions in physical systems. Instead of local order parameters, topological phases are described by global topological invariants and are therefore robust against perturbations. A prominent example thereof is the two-dimensional integer quantum Hall effect. It is characterized by the first Chern number which manifests in the quantized Hall response induced by an external electric field. Generalizing the quantum Hall effect to four-dimensional systems leads to the appearance of a novel non-linear Hall response that is quantized as well, but described by a 4D topological invariant - the second Chern number. Here, we report on the first observation of a bulk response with intrinsic 4D topology and the measurement of the associated second Chern number. By implementing a 2D topological charge pump with ultracold bosonic atoms in an angled optical superlattice, we realize a dynamical version of the 4D integer quantum Hall effect. Using a small atom cloud as a local probe, we fully characterize the non-linear response of the system by in-situ imaging and site-resolved band mapping. Our findings pave the way to experimentally probe higher-dimensional quantum Hall systems, where new topological phases with exotic excitations are predicted

Massive Star Forming Regions in the Galaxy using the Spitzer GLIMPSE Survey

We examine the thirteen most luminous sources in the WMAP free-free map using the Spitzer GLIMPSE and MSX surveys to identify massive star formation regions, emitting one-third of the Galactic free-free luminosity. We identify star forming regions by a combination of bubble morphology in 8 \micronm (PAH) emission and radio recombination line radial velocities. We find 40 star forming regions associated with our WMAP sources, and determine unique distances to 31. We interpret the bubbles as evidence for radial expansion. The radial velocity distribution for each source allows us to measure the intrinsic speed of a region's expansion. This speed is consistent with the size and age of the bubbles. The high free-free luminosities, combined with negligible synchrotron emission, demonstrate that the bubbles are not driven by supernovae. The kinetic energy of the largest bubbles is a substantial fraction of that measured in the older superbubbles found by Heiles. We find that the energy injected into the ISM by our bubbles is similar to that required to maintain the turbulent motion in the gas disk inside 8 kpc. We report a number of new star forming regions powered by massive (\textrm{M}_{*} > 10^4 \textrm{M}_\sun) star clusters. We measure the scale height of the Galactic O stars to be h_{\textrm{*}} = 35 \pm 5 \pc. We determine an empirical relationship between the PAH and free-free emission of the form $F_{\textrm{PAH}} \propto F^2_{\textrm{ff}}$. Finally, we find that the bubble geometry is more consistent with a spherical shell rather than a flattened disk.Comment: Submitted to ApJ; 29 Pages, 17 Figures, 5 Table

The Structure of the Interstellar Medium of Star Forming Galaxies

We present numerical methods for including stellar feedback in galaxy-scale simulations. We include heating by SNe (I & II), gas recycling and shock-heating from O-star & AGB winds, HII photoionization, and radiation pressure from stellar photons. The energetics and time-dependence are taken directly from stellar evolution models. We implement these in simulations with pc-scale resolution, modeling galaxies from SMC-like dwarfs and MW analogues to massive z~2 starburst disks. Absent feedback, gas cools and collapses without limit. With feedback, the ISM reaches a multi-phase steady state in which GMCs continuously form, disperse, and re-form. Our primary results include: (1) Star forming galaxies generically self-regulate at Toomre Q~1. Most of the volume is in diffuse hot gas with most of the mass in dense GMC complexes. The phase structure and gas mass at high densities are much more sensitive probes of stellar feedback physics than integrated quantities (Toomre Q or gas velocity dispersion). (2) Different feedback mechanisms act on different scales: radiation & HII pressure are critical to prevent runaway collapse of dense gas in GMCs. SNe and stellar winds dominate the dynamics of volume-filling hot gas; however this primarily vents out of the disk. (3) The galaxy-averaged SFR is determined by feedback. For given feedback efficiency, restricting star formation to molecular gas or modifying the cooling function has little effect; but changing feedback mechanisms directly translates to shifts off the Kennicutt-Schmidt relation. (4) Self-gravity leads to marginally-bound GMCs with an ~M^-2 mass function with a cutoff at the Jeans mass; they live a few dynamical times before being disrupted by stellar feedback and turn ~1-10% of their mass into stars (increasing from dwarfs through starburst galaxies). Low-mass GMCs are preferentially unbound.Comment: 34 pages, 24 figures, accepted to MNRAS (matches accepted version). Movies of the simulations are available at https://www.cfa.harvard.edu/~phopkins/Site/Movies_sbw.htm