Circularizing Planet Nine through dynamical friction with an extended, cold planetesimal belt

Unexpected clustering in the orbital elements of minor bodies beyond the Kuiper belt has led to speculations that our solar system actually hosts nine planets, the eight established plus a hypothetical "Planet Nine". Several recent studies have shown that a planet with a mass of about 10 Earth masses on a distant eccentric orbit with perihelion far beyond the Kuiper belt could create and maintain this clustering. The evolutionary path resulting in an orbit such as the one suggested for Planet Nine is nevertheless not easily explained. Here we investigate whether a planet scattered away from the giant-planet region could be lifted to an orbit similar to the one suggested for Planet Nine through dynamical friction with a cold, distant planetesimal belt. Recent simulations of planetesimal formation via the streaming instability suggest that planetesimals can readily form beyond 100au. We explore this circularisation by dynamical friction with a set of numerical simulations. We find that a planet that is scattered from the region close to Neptune onto an eccentric orbit has a 20-30% chance of obtaining an orbit similar to that of Planet Nine after 4.6Gyr. Our simulations also result in strong or partial clustering of the planetesimals; however, whether or not this clustering is observable depends on the location of the inner edge of the planetesimal belt. If the inner edge is located at 200au the degree of clustering amongst observable objects is significant.Comment: Accepted to MNRA

Drafting and Use of Opinion Letters of Counsel

This article outlines the kinds of opinions which counsel may render to a non-client via letter, the functions of such opinions in a transaction, and the preparation of opinion letters in view of the possibility of counsel\u27s liability thereon to a non-client party. Material for the article was obtained in part from interviews with a number of individuals familiar with transactions commonly involving opinion letters and more particularly transactions wherein opinion letters are transmitted to non-clients for their reliance

City of Trenton Natural Resource Inventory (NRI)

This publication documents the natural resources of the City of Trenton, Mercer County, New Jersey. There are descriptions, tables, and maps of: land use; soils; surface waters, including watersheds, streams, wetlands, and floodplains; land use/land cover and natural vegetation; threatened and endangered species; known contaminated sites; air quality; and climate

The Legacy of Geopolitics

In fact, we in America began to use the term ourselves and even now continue to use it to a considerable extent. It is of interest, therefore, to consider what, of all this business of geopolitics that was so ballyhooed by the Germans before and during World War II, remains to us today as something really valid that we, too, can properly use in carrying out our national strategy

Geometrically exact Cosserat rods with Kelvin–Voigt type viscous damping

We present the derivation of a simple viscous damping model of Kelvin–Voigt type for geometrically exact Cosserat rods from three-dimensional continuum theory. Assuming moderate curvature of the rod in its reference configuration, strains remaining small in its deformed configurations, strain rates that vary slowly compared to internal relaxation processes, and a homogeneous and isotropic material, we obtain explicit formulas for the damping parameters of the model in terms of the well known stiffness parameters of the rod and the retardation time constants defined as the ratios of bulk and shear viscosities to the respective elastic moduli. We briefly discuss the range of validity of the Kelvin–Voigt model and illustrate its behaviour for large bending deformations with a numerical example

Ovalbumin sensitization and challenge increases the number of lung cells possessing a mesenchymal stromal cell phenotype

Abstract Background Recent studies have indicated the presence of multipotent mesenchymal stromal cells (MSCs) in human lung diseases. Excess airway smooth muscle, myofibroblasts and activated fibroblasts have each been noted in asthma, suggesting that mesenchymal progenitor cells play a role in asthma pathogenesis. We therefore sought to determine whether MSCs are present in the lungs of ovalbumin (OVA)-sensitized and challenged mice, a model of allergic airways disease. Methods Balb/c mice were sensitized and challenged with PBS or OVA over a 25 day period. Flow cytometry as well as colony forming and differentiation potential were used to analyze the emergence of MSCs along with gene expression studies using immunochemical analyses, quantitative polymerase chain reaction (qPCR), and gene expression beadchips. Results A CD45-negative subset of cells expressed Stro-1, Sca-1, CD73 and CD105. Selection for these markers and negative selection against CD45 yielded a population of cells capable of adipogenic, osteogenic and chondrogenic differentiation. Lungs from OVA-treated mice demonstrated a greater average colony forming unit-fibroblast (CFU-F) than control mice. Sorted cells differed from unsorted lung adherent cells, exhibiting a pattern of gene expression nearly identical to bone marrow-derived sorted cells. Finally, cells isolated from the bronchoalveolar lavage of a human asthma patient showed identical patterns of cell surface markers and differentiation potential. Conclusions In summary, allergen sensitization and challenge is accompanied by an increase of MSCs resident in the lungs that may regulate inflammatory and fibrotic responses.http://deepblue.lib.umich.edu/bitstream/2027.42/78265/1/1465-9921-11-127.xmlhttp://deepblue.lib.umich.edu/bitstream/2027.42/78265/2/1465-9921-11-127.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/78265/3/1465-9921-11-127-S1.DOCPeer Reviewe

Prevention of Glaucoma-Induced Retinal Ganglion Cell Loss Using Alpha7 nAChR Agonists

In this study, the neuroprotective effect of various nicotinic alpha7 acetylcholine receptor agonists in an in-vivo model of glaucoma using adult Long Evans rats was analyzed. Glaucoma-like conditions were induced in the eyes of Long Evans rats after injection of hypertonic saline into episcleral veins to create scar tissue and increase the animal’s intraocular pressure. This procedure produced significant loss of retinal ganglion cells within one month and was associated with an increase of intraocular pressure. Using this model system, various alpha7 nicotinic acetylcholine receptor (a7 nAChR) agonists were applied at different doses as eye drops to the right eye of adult Long Evans rats while the left eye was left as an internal control. The a7 nAChR agonists used in this study prevented loss of RGCs in a dose dependent manner after the procedure to induce glaucoma-like conditions. PHA-543613 and PNU- 282987 provided the largest degree of RGC survival after inducing glaucomalike conditions, followed by nicotine, SEN 12333, tropisetron, 3-Bromocytisine and DMAB. To provide evidence that neuroprotection of RGCs was mediated through activation of a7 nAChR, in some studies different concentrations of the a7 nAChR antagonist, MLA, was intravitreally injected into experimentally treated eyes before initiation of eye drops and the procedure to induce glaucoma-like conditions. In the presence of MLA, RGC neuroprotection was blocked. Results from these studies suggest that selective a7 nAChR agonists may be used in future therapeutic treatments for glaucoma or other CNS diseases associated with a7 nAChRs