The Velocity Function of Galaxies

We present a galaxy circular velocity function, Psi(log v), derived from existing luminosity functions and luminosity-velocity relations. Such a velocity function is desirable for several reasons. First, it enables an objective comparison of luminosity functions obtained in different bands and for different galaxy morphologies, with a statistical correction for dust extinction. In addition, the velocity function simplifies comparison of observations with predictions from high-resolution cosmological N-body simulations. We derive velocity functions from five different data sets and find rough agreement among them, but about a factor of 2 variation in amplitude. These velocity functions are then compared with N-body simulations of a LCDM model (corrected for baryonic infall) in order to demonstrate both the utility and current limitations of this approach. The number density of dark matter halos and the slope of the velocity function near v_*, the circular velocity corresponding to an ~L_* spiral galaxy, are found to be comparable to that of observed galaxies. The primary sources of uncertainty in construction of Psi(log v) from observations and N-body simulations are discussed and explanations are suggected to account for these discrepancies.Comment: Latex. 28 pages, 4 figures. Accepted by Ap

Natural stimulus responsive scaffolds/cells for bone tissue engineering : influence of lysozyme upon scaffold degradation and osteogenic differentiation of cultured marrow stromal cells induced by CaP coatings

This work proposes the use of nonporous, smart, and stimulus responsive chitosan-based scaffolds for bone tissue engineering applications. The overall vision is to use biodegradable scaffolds based on chitosan and starch that present properties that will be regulated by bone regeneration, with the capability of gradual in situ pore formation. Biomimetic calcium phosphate (CaP) coatings were used as a strategy to incorporate lysozyme at the surface of chitosan-based materials with the main objective of controlling and tailoring their degradation profile as a function of immersion time. To confirm the concept, degradation tests with a lysozyme concentration similar to that incorporated into CaP chitosan-based scaffolds were used to study the degradation of the scaffolds and the formation of pores as a function of immersion time. Degradation studies with lysozyme (1.5 g=L) showed the formation of pores, indicating an increase of porosity (*5–55% up to 21 days) resulting in porous threedimensional structures with interconnected pores. Additional studies investigated the influence of a CaP biomimetic coating on osteogenic differentiation of rat marrow stromal cells (MSCs) and showed enhanced differentiation of rat MSCs seeded on the CaP-coated chitosan-based scaffolds with lysozyme incorporated. At all culture times, CaP-coated chitosan-based scaffolds with incorporated lysozyme demonstrated greater osteogenic differentiation of MSCs, bone matrix production, and mineralization as demonstrated by calcium deposition measurements, compared with controls (uncoated scaffolds). The ability of these CaP-coated chitosan-based scaffolds with incorporated lysozyme to create an interconnected pore network in situ coupled with the demonstrated positive effect of these scaffolds upon osteogenic differentiation of MSCs and mineralized matrix production illustrates the strong potential of these scaffolds for application in bone tissue engineering strategies.The authors would like to acknowledge Dr. Serena Danti. This work was supported by the European NoE EX-PERTISSUES (NMP3-CT-2004-500283), the European STREP HIPPOCRATES (NMP3-CT-2003-505758), and the Portuguese Foundation for Science and Technology (FCT) through POCTI and/or FEDER programs. This work was also supported by a grant from the National Institutes of Health (NIH; R01 DE15164) (A. G. M.) and a Bioengineering Research Partnership with the Baylor College of Medicine through the National Institute of Biomedical Imaging and Bioengineering (NIH Grant 5 R01 EB005173-02). F. K. K. is supported by a training fellowship from the Keck Center Nanobiology Training Program of the Gulf Coast Consortia (NIH Grant 5 T90 DK070121-03)

Accelerated Oxygen Atom Transfer and C−H Bond Oxygenation by Remote Redox Changes in Fe_3Mn-Iodosobenzene Adducts

We report the synthesis, characterization, and reactivity of [Lfe_3(PhPz)_3OMn(^sPhIO)][OTf]_x (3: x=2; 4: x=3), where 4 is one of very few examples of iodosobenzene–metal adducts characterized by X-ray crystallography. Access to these rare heterometallic clusters enabled differentiation of the metal centers involved in oxygen atom transfer (Mn) or redox modulation (Fe). Specifically, ^(57)Fe Mössbauer and X-ray absorption spectroscopy provided unique insights into how changes in oxidation state (Fe^(III)_2Fe^(II)Mn^(II) vs. Fe^(III)_3Mn^(II)) influence oxygen atom transfer in tetranuclear Fe_3Mn clusters. In particular, a one-electron redox change at a distal metal site leads to a change in oxygen atom transfer reactivity by ca. two orders of magnitude

Fabrication and characterization of multiscale electrospun scaffolds for cartilage regeneration

Recently, scaffolds for tissue regeneration purposes have been observed to utilize nanoscale features in an effort to reap the cellular benefits of scaffold features resembling extracellular matrix (ECM) components. However, one complication surrounding electrospun nanofibers is limited cellular infiltration. One method to ameliorate this negative effect is by incorporating nanofibers into microfibrous scaffolds. This study shows that it is feasible to fabricate electrospun scaffolds containing two differently scaled fibers interspersed evenly throughout the entire construct as well as scaffolds containing fibers composed of two discrete materials, specifically fibrin and poly(?-caprolactone). In order to accomplish this, multiscale fibrous scaffolds of different compositions were generated using a dual extrusion electrospinning setup with a rotating mandrel. These scaffolds were then characterized for fiber diameter, porosity and pore size and seeded with human mesenchymal stem cells to assess the influence of scaffold architecture and composition on cellular responses as determined by cellularity, histology and glycosaminoglycan (GAG) content. Analysis revealed that nanofibers within a microfiber mesh function to maintain scaffold cellularity under serum-free conditions as well as aid the deposition of GAGs. This supports the hypothesis that scaffolds with constituents more closely resembling native ECM components may be beneficial for cartilage regeneration

Fetal origins of malarial disease: cord blood cytokines as risk markers for pediatric severe malarial anemia.

BACKGROUND: Severe malarial anemia (SMA) remains a major cause of pediatric illness and mortality in Sub-Saharan Africa. Here we test the hypothesis that prenatal exposures, reflected by soluble inflammatory mediators in cord blood, can condition an individual's susceptibility to SMA. METHODS: In a Tanzanian birth cohort (n = 743), we measured cord blood concentrations of tumor necrosis factor (TNF), TNF receptors I and II (TNF-RI and TNF-RII), interleukin (IL)-1β, IL-4, IL-5, IL-6, IL-10, and interferon gamma (IFN-γ). After adjusting for conventional covariates, we calculated the hazard ratios (HR) for time to first SMA event with log(e) cytokine concentrations dichotomized at the median, by quartile, and per standard deviation (SD) increase. RESULTS: Low levels of TNF, TNF-RI, IL-1β, and IL-5 and high levels of TNF-RII were associated statistically significantly and respectively with approximately 3-fold, 2-fold, 8-fold, 4-fold, and 3-fold increased risks of SMA (Hb < 50 g/L). TNF, TNF-RI, and IL-1β concentrations were inversely and log-linearly associated with SMA risk; the HR (95% confidence interval [CI]) per 1-SD increase were respectively 0.81 (.65, 1.02), 0.76 (.62, .92), and 0.50 (.40, .62). CONCLUSIONS: These data suggest that proinflammatory cytokine levels at birth are inversely associated with SMA risk and support the hypothesis that pediatric malarial disease has fetal origins

Imaging of poly(α-hydroxy-ester) scaffolds with X-ray phase-contrast microcomputed tomography

Porous scaffolds based on poly(α-hydroxy-esters) are under investigation in many tissue engineering applications. A biological response to these materials is driven, in part, by their three-dimensional (3D) structure. The ability to evaluate quantitatively the material structure in tissue-engineering applications is important for the continued development of these polymer-based approaches. X-ray imaging techniques based on phase contrast (PC) have shown a tremendous promise for a number of biomedical applications owing to their ability to provide a contrast based on alternative X-ray properties (refraction and scatter) in addition to X-ray absorption. In this research, poly(α-hydroxy-ester) scaffolds were synthesized and imaged by X-ray PC microcomputed tomography. The 3D images depicting the X-ray attenuation and phase-shifting properties were reconstructed from the measurement data. The scaffold structure could be imaged by X-ray PC in both cell culture conditions and within the tissue. The 3D images allowed for quantification of scaffold properties and automatic segmentation of scaffolds from the surrounding hard and soft tissues. These results provide evidence of the significant potential of techniques based on X-ray PC for imaging polymer scaffolds

Quantification of Porosity and Sorptivity in Fiber-Reinforced 3D-Printed Mortar: Connecting Material Composition and Structural Performance

Existing literature suggests an important connection between porosity in 3D printed cementitious composites (3DPC) and mechanical behavior, including strength, anisotropy, and permeability. Much of the body of knowledge shows that the relationship is more pronounced in 3DPC than in cast concrete [1–9]. In this preliminary study, quantitative observations of material microstructure, obtained by computed microtomography performed before and after fluid ingress, are combined with measurements of bulk sorptivity to compare the porosity of printed and cast samples of the same mortar. Measurements are taken near the extruded specimen edge and in the bulk (i.e. internal) of printed and cast specimens made from a fiber-reinforced material

\u3ci\u3eThe Unfortunate Traveller\u3c/i\u3e and the Ramist Controversy: A Narrative Dilemma

The narrative and rhetorical structure of Thomas Nashe\u27s The Unfortunate Traveller has vexed its critics almost since its initial appearance in 1593. Most modern critics have followed a line something akin to that of G.R. Hibbard, who sees Nashe as a writer unable at times to distinguish his own voice from that of the narrator, Jack Wilton. Stephen Hilliard’s study of Nashe notes the critical tendency to see The Unfortunate Traveller as “a formless work, spun out by a careless author with no fixed purpose” and, though he chides such critics for ignoring its many virtues, grants that they likely “reflect a truth” about its composition. Even ardent admirers of the work, such as Nashe biographer Charles Nicholl, say it presents “a sense of life as a series of episodic fragments.