1,112 research outputs found
Stratigraphy and Conodont Paleontology of the Salamonie Dolomite and Lee Creek Member of the Brassfield Limestone (Silurian) In Southeastern Indiana and Adjacent Kentucky
Indiana Geological Survey Bulletin 40Zonation established by study of the conodont faunas of the Lee Creek Member (new member) of the Brassfield Limestone and of the Salamonie Dolomite, both of Silurian age, from 42 sections in southeastern Indiana and north-central Kentucky differs from the conodont zonation established by O. H. Walliser in 1964 for the lower Silurian and lower part of the middle Silurian rocks of the Carnic Alps of Europe. Three conodont assemblage zones are named. In ascending order these are the Icriodina irregularis Assemblage Zone, the Neospathognathodus
celloni Assemblage Zone, and the Pterospathodus amorphognathoides-Spathognathodus ranuliformis Assemblage Zone. These zones correspond in general with the upper part of Walliser’s Bereich I and with his celloni-and amorphognathoides-Zones. The new name Lee Creek Member is applied to a thin dolomite unit at the top of the Brassfield Limestone.
Fifty-nine named species, 16 of them new, belonging to 22 genera, two of them new, were identified from about 8,900 specimens obtained in this study. The new taxa include the genera Diadelognathus and Neospathognathodus and the species Diadelognathus compressus, D. excertus, D. primus, Drepanodus aduncus, Ligonodina petila, Neospathognathodus bullatus, N. ceratoides, N. latus, Ozarkodina hanoverensis, 0. neogaertneri, Spathognathodus hadros, S. polinclinatus, Synprioniodina? variabilis, Trichonodella asymmetrica, T.? expansa, and T. papilio. Two species each of Diadelognathus and of Paltodus, and one each of Carniodus, Distacodus?, and Trichonodella are described but not named.Indiana Department of Natural Resource
Photo-Crosslinked Alginate Hydrogels Support Enhanced Matrix Accumulation by Nucleus Pulposus Cells in Vivo
Objective Intervertebral disc (IVD) degeneration is a major health concern in the United States. Replacement of the nucleus pulposus (NP) with injectable biomaterials represents a potential treatment strategy for IVD degeneration. The objective of this study was to characterize the extracellular matrix (ECM) assembly and functional properties of NP cell-encapsulated, photo-crosslinked alginate hydrogels in comparison to ionically crosslinked alginate constructs. Methods Methacrylated alginate was synthesized by esterification of hydroxyl groups with methacrylic anhydride. Bovine NP cells were encapsulated in alginate hydrogels by ionic crosslinking using CaCl2 or through photo-crosslinking upon exposure to long-wave UV light in the presence of a photoinitiator. The hydrogels were evaluated in vitro by gross and histological analysis and in vivo using a murine subcutaneous pouch model. In vivo samples were analyzed for gene expression, ECM localization and accumulation, and equilibrium mechanical properties. Results Ionically crosslinked hydrogels exhibited inferior proteoglycan accumulation in vitro and were unable to maintain structural integrity in vivo. In further studies, photo-crosslinked alginate hydrogels were implanted for up to 8 weeks to examine NP tissue formation. Photo-crosslinked hydrogels displayed temporal increases in gene expression and assembly of type II collagen and proteoglycans. Additionally, hydrogels remained intact over the duration of the study and the equilibrium Young\u27s modulus increased from 1.24 ± 0.09 kPa to 4.31 ± 1.39 kPa, indicating the formation of functional matrix with properties comparable to those of the native NP. Conclusions These findings support the use of photo-crosslinked alginate hydrogels as biomaterial scaffolds for NP replacement
Giant Stark effect in the emission of single semiconductor quantum dots
We study the quantum-confined Stark effect in single InAs/GaAs quantum dots
embedded within a AlGaAs/GaAs/AlGaAs quantum well. By significantly increasing
the barrier height we can observe emission from a dot at electric fields of
-500 kV/cm, leading to Stark shifts of up to 25 meV. Our results suggest this
technique may enable future applications that require self-assembled dots with
transitions at the same energy
Cell autonomous regulation of herpes and influenza virus infection by the circadian clock.
Viruses are intracellular pathogens that hijack host cell machinery and resources to replicate. Rather than being constant, host physiology is rhythmic, undergoing circadian (∼24 h) oscillations in many virus-relevant pathways, but whether daily rhythms impact on viral replication is unknown. We find that the time of day of host infection regulates virus progression in live mice and individual cells. Furthermore, we demonstrate that herpes and influenza A virus infections are enhanced when host circadian rhythms are abolished by disrupting the key clock gene transcription factor Bmal1. Intracellular trafficking, biosynthetic processes, protein synthesis, and chromatin assembly all contribute to circadian regulation of virus infection. Moreover, herpesviruses differentially target components of the molecular circadian clockwork. Our work demonstrates that viruses exploit the clockwork for their own gain and that the clock represents a novel target for modulating viral replication that extends beyond any single family of these ubiquitous pathogens.A.B.R. acknowledges funding from the Wellcome Trust (083643/Z/07/Z, 100333/Z/12/Z and 100574/Z/12/Z), the European Research Council (ERC Starting Grant No. 281348, MetaCLOCK), the EMBO Young Investigators Programme, the Lister Institute of Preventative Medicine and the Medical Research Council (MRC_MC_UU_12012/5). A.D.N acknowledges funding from the People Programme (Marie Curie Actions) of the European Union Seventh Framework Programme (FP7/2007-2013; REA grant agreement 627630). We thank L. Ansel-Bollepalli for assistance with animal breeding, I. Robinson for assistance with pilot animal experiments, A. Snijders and H. Flynn (Francis Crick Institute Proteomics Core) for help with proteomics work, Cambridge NIHR BRC Cell Phenotyping Hub for flow cytometry assistance, A. Miyawaki (RIKEN Brain Science Institute, Japan) for Fucci2 lentiviral vectors, and H. Coleman, J. May and M. Jain for helpful discussions. We thank Prof J. Bass (Northwestern University, USA) for Bmal-/- mouse embryonic fibroblasts used in preliminary experiments, and N. Heaton and P. Palese (Icahn School of Medicine at Mount Sinai, USA) for PB2::Gaussia luciferase IAV (PR8 PB2::GLUC).This is the author accepted manuscript. The final version is available from the National Academy of Sciences via http://dx.doi.org/10.1073/pnas.160189511
Flow Equations for U_k and Z_k
By considering the gradient expansion for the wilsonian effective action S_k
of a single component scalar field theory truncated to the first two terms, the
potential U_k and the kinetic term Z_k, I show that the recent claim that
different expansion of the fluctuation determinant give rise to different
renormalization group equations for Z_k is incorrect. The correct procedure to
derive this equation is presented and the set of coupled differential equations
for U_k and Z_k is definitely established.Comment: 5 page
Parallel pumping of electrons
We present simultaneous operation of ten single-electron turnstiles leading
to one order of magnitude increase in current level up to 100 pA. Our analysis
of device uniformity and background charge stability implies that the
parallelization can be made without compromising the strict requirements of
accuracy and current level set by quantum metrology. In addition, we discuss
how offset charge instability limits the integration scale of single-electron
turnstiles.Comment: 6 pages, 4 figures, 1 tabl
By design : negotiating flexible learning in the built environment discipline
The term ‘flexible education’ is now firmly entrenched within Australian higher education discourse, yet the term is a contested one imbued with a multiplicity of meanings. This paper describes a process designed to elucidate how the idea of flexible education can be translated into teaching models that are informed by the specific demands of disciplinary contexts. The process uses a flexible learning ‘matching’ tool to articulate the understandings and preferences of students and academics of the Built Environment to bridge the gap between student expectations of flexibility and their teacher’s willingness and ability to provide that flexibility within the limits of the pedagogical context and teaching resources. The findings suggest an informed starting point for educators in the Built Environment and other creative disciplines from which to traverse the complexities inherent in negotiating flexibility in an increasingly digital world
Tests of Statistical Methods for Estimating Galaxy Luminosity Function and Applications to the Hubble Deep Field
We studied the statistical methods for the estimation of the luminosity
function (LF) of galaxies. We focused on four nonparametric estimators:
estimator, maximum-likelihood estimator of Efstathiou et al.
(1988), Cho{\l}oniewski's estimator, and improved Lynden-Bell's estimator. The
performance of the estimator has been recently questioned,
especially for the faint-end estimation of the LF. We improved these estimators
for the studies of the distant Universe, and examined their performances for
various classes of functional forms by Monte Carlo simulations. We also applied
these estimation methods to the mock 2dF redshift survey catalog prepared by
Cole et al. (1998). We found that estimator yields a completely
unbiased result if there is no inhomogeneity, but is not robust against
clusters or voids. This is consistent with the well-known results, and we did
not confirm the bias trend of estimator claimed by Willmer
(1997) in the case of homogeneous sample. We also found that the other three
maximum-likelihood type estimators are quite robust and give consistent results
with each other. In practice we recommend Cho{\l}oniewski's estimator for two
reasons: 1. it simultaneously provides the shape and normalization of the LF;
2. it is the fastest among these four estimators, because of the algorithmic
simplicity. Then, we analyzed the photometric redshift data of the Hubble Deep
Field prepared by Fern\'{a}ndez-Soto et al. (1999) using the above four
methods. We also derived luminosity density at - and
-band. Our -band estimation is roughly consistent with that of Sawicki,
Lin, & Yee (1997), but a few times lower at . The evolution of
is found to be less prominent.Comment: To appear in ApJS July 2000 issue. 36 page
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