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Magnetized Accretion and Dead Zones in Protostellar Disks

The edges of magnetically-dead zones in protostellar disks have been proposed as locations where density bumps may arise, trapping planetesimals and helping form planets. Magneto-rotational turbulence in magnetically-active zones provides both accretion of gas on the star and transport of mass to the dead zone. We investigate the location of the magnetically-active regions in a protostellar disk around a solar-type star, varying the disk temperature, surface density profile, and dust-to-gas ratio. We also consider stellar masses between 0.4 and 2 $M_\odot$, with corresponding adjustments in the disk mass and temperature. The dead zone's size and shape are found using the Elsasser number criterion with conductivities including the contributions from ions, electrons, and charged fractal dust aggregates. The charged species' abundances are found using the approach proposed by S. Okuzumi. The dead zone is in most cases defined by the ambipolar diffusion. In our maps, the dead zone takes a variety of shapes, including a fish-tail pointing away from the star and islands located on and off the midplane. The corresponding accretion rates vary with radius, indicating locations where the surface density will increase over time, and others where it will decrease. We show that density bumps do not readily grow near the dead zone's outer edge, independently of the disk parameters and the dust properties. Instead, the accretion rate peaks at the radius where the gas-phase metals freeze out. This could lead to clearing a valley in the surface density, and to a trap for pebbles located just outside the metal freeze-out line.Comment: 58 pages, 25 figures, 2 tables, accepted to Ap

Surfactant protein genetics in community-acquired pneumonia: balancing the host inflammatory state

Community-acquired pneumonia is a common disease. Abnormalities in the first step of host defense may severely compromise subsequent steps of successfully combating infections. In the previous issue of Critical Care, García-Laorden and colleagues reported genetic associations between single-nucleotide polymorphisms and haplotypes of the surfactant proteins with susceptibility, severity, and outcome of community-acquired pneumonia. Although the limited information shows regulatory differences among variants, it is currently unknown how the difference in surfactant protein A genotypes in this and other studies affects the individual's phenotype. The lung is continually exposed to a host of irritants yet maintains health. It is plausible that, under physiologic conditions, surfactant protein A, in addition to having a dominant effect on anti-inflammatory processes, mediates a low level of proinflammatory processes that are essential for the health of the lung. Understanding the maintenance of the balance of the inflammatory state may be one of the keys to understanding pulmonary disease progression

Transport and digestive alteration of uniformly 13C-labeled diatoms in mudflat sediments

Uniformly 13C-labeled diatoms were used to elucidate the effect deposit feeders have on the distribution and composition of phytodetritus within the seabed. Mudflat infauna contained in microcosms reacted quickly to the emplacement of labeled diatoms onto the sediment-water interface by moving the phytodetritus nonlocally during feeding and hoeing activities. Although redistribution of tracer was rapid, not all infauna exposed to the tracer ingested it. Using four species of deposit-feeding annelids that had ingested the 13C-labeled phytodetritus during the microcosm experiment, molecular-level, digestive alterations of 13C-labeled diatoms were documented. Fecal material produced by the deposit feeders had 13C amino acid signatures distinctly different from that of the diatom. Alterations in the amino acid composition of the diatom were correlated to the gut morphology and digestive physiology of the polychaete taxa

Analysis of Laboratory Management Competencies in Nebraska Agricultural Education Programs

Laboratory learning has long been associated with the educational process. The use of school and community laboratories in which students “learn by doing” is an integral part of agricultural education programs (Sutphin, 1984). Effective scheduling and management of the agricultural mechanics laboratory is a must for carrying out an effective instructional program (Shinn, 1987; Bear & Hoemer, 1986). The ability to manage laboratory learning was rated as a highly important ability for agriculture teachers by first-year agriculture teachers (Barrick and Powell, 1986). Agriculture instructors must be prepared so they possess and practice laboratory management competencies in order to maximize the opportunity for student learning (Henderson, 1983). Johnson and Schumacher (1989) defied laboratory management competencies as those abilities needed by secondary agriculture teachers to direct, conduct, or administer an agricultural mechanics laboratory. Hoerner and Bekkum (1990) reported that agriculture instructors in seven selected states taught an average of two agricultural mechanics classes per semester. Schlautman and Foster (1991) indicated that secondary agricultural education teachers in Nebraska devoted 29.6 percent of their time to agricultural mechanics instruction. Many agriculture courses allot one-third to two-thirds of the total instructional time to individual and group laboratory activities (Shinn, 1987). The large percentage of instructional time spent in laboratory settings suggests the need for sound laboratory management practices. Johnson et. al. (1990) found that Missouri secondary agriculture teachers have in-service needs in the area of agricultural mechanics laboratory management. The greatest in-service needs were in the area of safety. Johnson et. al. suggested research be conducted to identify a core of common laboratory management competencies essential to all phases of laboratory instruction. Johnson and Schumacher (1989) surveyed post-secondary, college and university agricultural mechanics experts to identify and prioritize a list of 50 laboratory management competencies which the experts perceived as important in order to effectively manage a secondary school agriculture mechanics laboratory. The authors concluded that teacher educators should provide present and prospective agriculture teachers experiences designed to develop and enhance these skills. They also stated that further research should be conducted to determine the extent to which agriculture teachers possess and practice these laboratory management competencies. This study was conducted in response to their call for further research

Accuracy, Scalability, and Efficiency of Mixed-Element USM3D for Benchmark Three-Dimensional Flows

The unstructured, mixed-element, cell-centered, finite-volume flow solver USM3D is enhanced with new capabilities including parallelization, line generation for general unstructured grids, improved discretization scheme, and optimized iterative solver. The paper reports on the new developments to the flow solver and assesses the accuracy, scalability, and efficiency. The USM3D assessments are conducted using a baseline method and the recent hierarchical adaptive nonlinear iteration method framework. Two benchmark turbulent flows, namely, a subsonic separated flow around a three-dimensional hemisphere-cylinder configuration and a transonic flow around the ONERA M6 wing are considered

An unexpected diagnosis of methicillin-resistant Staphylococcus aureus septic arthritis

Hand infections can result in serious tissue damage and gross functional impairment. This is particularly true in the case of septic arthritis, the most destructive of all joint disease. We report the first case of methicillin-resistant Staphylococcus aureus septic arthritis of the distal interphalangeal joint to have occurred in a patient devoid of all risk factors traditionally associated with a hospital-associated infection (HA-MRSA). The afflicted patient's only exposure to the pathogen was during her role as a community carer for an asymptomatic carrier. Delayed treatment allowed the infection to rapidly destroy surrounding soft tissue and necessitate in the need for arthrodesis. It is, therefore imperative that clinicians maintain a low index of suspicion for methicillin-resistant Staphylococcus aureus as the causative pathogen in similar cases. Consequently, consideration of empirical antibiotic therapy for this patient subgroup is discussed

Cooperative heterometallic catalysts:balancing activity and control in PCL-block-PLA copolymer synthesis

Heterometallic cooperativity is gaining momentum in cyclic ester ring-opening polymerisation, yet remains surprisingly underexplored in their block copolymerisations. Here, we report the first homogeneous heterometallic “ate” catalysts for poly(ϵ-caprolactone)-poly(lactic acid) block copolymers, showcasing the substantial differences in the polymer structures observed upon exchanging Zn for Mg or Ca.</p

Superoxide dismutase 2 knockdown leads to defects in locomotor activity, sensitivity to paraquat, and increased cuticle pigmentation in Tribolium castaneum

Citation: Tabunoki, H., Gorman, M. J., Dittmer, N. T., & Kanost, M. R. (2016). Superoxide dismutase 2 knockdown leads to defects in locomotor activity, sensitivity to paraquat, and increased cuticle pigmentation in Tribolium castaneum. Scientific Reports, 6, 8. doi:10.1038/srep29583Insects can rapidly adapt to environmental changes through physiological responses. The red flour beetle Tribolium castaneum is widely used as a model insect species. However, the stress-response system of this species remains unclear. Superoxide dismutase 2 (SOD2) is a crucial antioxidative enzyme that is found in mitochondria. T. castaneum SOD2 (TcSOD2) is composed of 215 amino acids, and has an iron/manganese superoxide dismutase domain. qRT-PCR experiments revealed that TcSOD2 was present through all developmental stages. To evaluate TcSOD2 function in T. castaneum, we performed RNAi and also assessed the phenotype and antioxidative tolerance of the knockdown of TcSOD2 by exposing larvae to paraquat. The administration of paraquat resulted in significantly higher 24-h mortality in TcSOD2 knockdown larval groups than in the control groups. The TcSOD2 knockdown adults moved significantly more slowly, had lower ATP content, and exhibited a different body color from the control groups. We found that TcSOD2 dsRNA treatment in larvae resulted in increased expression of tyrosinase and laccase2 mRNA after 10 days. This is the first report showing that TcSOD2 has an antioxidative function and demonstrates that T. castaneum may use an alternative antioxidative system when the SOD2-based system fails