3,233 research outputs found
Epidemiology and potential preventative measures for viral infections in children with malignancy and those undergoing hematopoietic cell transplantation.
In pediatric patients with malignancy and those receiving hematopoietic stem cell transplants, bacterial and fungal infections have been the focus of fever and neutropenia episodes for decades. However, improved diagnostic capabilities have revealed viral pathogens as a significant cause of morbidity and mortality. Because of limited effective antiviral therapies, prevention of viral infections is paramount. Pre-exposure and post-exposure prophylaxis and antiviral suppressive therapeutic approaches are reviewed. Additionally, infection control practices specific to this patient population are discussed. A comprehensive approach utilizing each of these can be effective at reducing the negative impact of viral infections
Sub-Alfvenic Non-Ideal MHD Turbulence Simulations with Ambipolar Diffusion: I. Turbulence Statistics
Most numerical investigations on the role of magnetic fields in turbulent
molecular clouds (MCs) are based on ideal magneto-hydrodynamics (MHD). However,
MCs are weakly ionized, so that the time scale required for the magnetic field
to diffuse through the neutral component of the plasma by ambipolar diffusion
(AD) can be comparable to the dynamical time scale. We have performed a series
of 256^3 and 512^3 simulations on supersonic but sub-Alfvenic turbulent systems
with AD using the Heavy-Ion Approximation developed in Li, McKee, & Klein
(2006). Our calculations are based on the assumption that the number of ions is
conserved, but we show that these results approximately apply to the case of
time-dependent ionization in molecular clouds as well. Convergence studies
allow us to determine the optimal value of the ionization mass fraction when
using the heavy-ion approximation for low Mach number, sub-Alfvenic turbulent
systems. We find that ambipolar diffusion steepens the velocity and magnetic
power spectra compared to the ideal MHD case. Changes in the density PDF, total
magnetic energy, and ionization fraction are determined as a function of the AD
Reynolds number. The power spectra for the neutral gas properties of a strongly
magnetized medium with a low AD Reynolds number are similar to those for a
weakly magnetized medium; in particular, the power spectrum of the neutral
velocity is close to that for Burgers turbulence.Comment: 37 pages, 11 figures, 4 table
A port by any other name: a preliminary spatial analysis of ancient infrastructural landscapes and settlement organization at Macurany, Brazil
Complex human-environmental processes form identifiable, lasting features on the landscape that can illuminate past human behavior and human-environment interactions. We examine the anthropogenic landscape of the ancient port of Macurany, located along the middle Amazon River in Parintins, Brazil, and identify four classes of anthropogenic landscape features at the site: wharfs, middens, terra preta (dark or black earths), and cultural forests. Middens, terra preta, and cultural forests have been found at archaeological sites in regions surrounding Macurany, but wharfs have not previously been reported in Amazonian contexts predating European contact. Taken together, these features are clearly the result of anthropogenesis and represent a range of subsistence, settlement, and infrastructure-building activities pointing to an ancient society that was actively engaged in modifying the surrounding landscape for purposes beyond settlement and subsistence. Evidence for a permanent, extensive, continuously settled society practicing intensive landscape engineering in this region of Amazonia reinforces findings of dense habitation, infrastructure, and early urbanization in Amazonia prior to European contact. This research helps expand our understanding of human-environment interactions, landscape formation processes, and settlement organization in ancient Amazonia.University of Louisville to Anna T. Browne Ribeiroinfo:eu-repo/semantics/publishedVersio
A new species of Eimeria Schneider, 1875 (Apicomplexa: Eimeriidae) from the Solomon ground skink, Sphenomorphus solomonis (Boulenger) (Sauria: Scincidae) from Papua New Guinea
Between September 1990 and November 1991, 19 Sphenomorphus spp. skinks, including nine S. jobiense, three S. simus, and seven Solomon ground skinks, S. solomonis (Boulenger), were collected from Madang and Morobe Provinces, Papua New Guinea (PNG), and examined for coccidia. A single S. solomonis was found to be infected with a new species of Eimeria Schneider, 1875. Oöcysts of Eimeria perkinsae n. sp. are ellipsoidal with a smooth, colourless, bi-layered wall, measure 18.6 × 14.7 μm, and have a length/width (L/W) ratio of 1.3; both micropyle and oöcyst residuum are absent, but a fragmented polar granule is present. Sporocysts are ovoidal, 8.9 × 6.4 μm, L/W 1.4; neither Stieda, sub-Stieda or para-Stieda bodies are present; a sporocyst residuum consisted of a loose cluster of granules dispersed between sporozoites. Sporozoites are comma-shaped with spheroidal anterior and posterior refractile bodies. This represents the first report of coccidia from this skink genus. © 2013 Springer Science+Business Media Dordrecht
Two new species of Eimeria (Apicomplexa, Eimeriidae) from tree skinks, Prasinohaema spp. (Sauria: Scincidae), from Papua New Guinea
Between September 1991 and June 1992, feces from 4 species of tree skinks, Prasinohaema spp. from Papua New Guinea, were collected and examined for coccidia. Two species, P. flavipes and P. prehensicauda were found to harbor eimerians which are described as new. Oocysts of Eimeria krausi sp. nov. from P. flavipes were ellipsoidal to subspheroidal with a smooth bilayered wall and measured (L × W) 19.2 × 16.9 μm, with a length/width (L/W) ratio of 1.1. Micropyle and oocyst residuum were absent but a fragmented polar granule was present. Sporocysts were ellipsoidal, 9.7 × 6.7 μm, L/W of 1.5. Stieda, subStieda and paraStieda bodies were absent. The sporocyst residuum was composed of many small granules in a compact mass between sporozoites. The sporozoites were sausage-shaped, 11.7 × 2.7 μm, in situ, with an ellipsoidal posterior refractile body and a spheroidal anterior refractile body. Oocysts of Eimeria greeri sp. nov. from P. prehensicauda were ellipsoidal with a smooth bilayered wall, (L × W) 23.0 × 18.3 μm, with a L/W of 1.3. Micropyle and oocyst residuum were absent but a fragmented polar granule was present. Sporocysts were ellipsoidal, 9.7 × 8.4 μm, with a L/W of 1.2. Stieda, subStieda and paraStieda bodies were absent. The sporocyst residuum was composed of many large granules in a compact mass between sporozoites. The sporozoites were sausage-shaped, with an ellipsoidal posterior refractile body and a spheroidal anterior refractile body. We document here the first report of coccidia from skinks of the genus Prasinohaema. © 2014 Versita Warsaw and Springer-Verlag Wien
Metabolic crosstalk: molecular links between glycogen and lipid metabolism in obesity.
Glycogen and lipids are major storage forms of energy that are tightly regulated by hormones and metabolic signals. We demonstrate that feeding mice a high-fat diet (HFD) increases hepatic glycogen due to increased expression of the glycogenic scaffolding protein PTG/R5. PTG promoter activity was increased and glycogen levels were augmented in mice and cells after activation of the mechanistic target of rapamycin complex 1 (mTORC1) and its downstream target SREBP1. Deletion of the PTG gene in mice prevented HFD-induced hepatic glycogen accumulation. Of note, PTG deletion also blocked hepatic steatosis in HFD-fed mice and reduced the expression of numerous lipogenic genes. Additionally, PTG deletion reduced fasting glucose and insulin levels in obese mice while improving insulin sensitivity, a result of reduced hepatic glucose output. This metabolic crosstalk was due to decreased mTORC1 and SREBP activity in PTG knockout mice or knockdown cells, suggesting a positive feedback loop in which once accumulated, glycogen stimulates the mTORC1/SREBP1 pathway to shift energy storage to lipogenesis. Together, these data reveal a previously unappreciated broad role for glycogen in the control of energy homeostasis
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