5,248 research outputs found
Geographic Variation of Cirques on Iceland: Factors Influencing Cirque Morphology
Cirques are one of the most common glacial landforms in alpine settings. They also provide important paleoclimate information (e.g. Meierding 1984; Evans 2006). The purpose of this study is to fill in gaps in the climate record of Iceland by conducting a quantitative analysis of cirques in three regions in Iceland: Tröllaskagi, the East Fjords, and VestfirĂ°ir. Iceland, located in the center of the North Atlantic Ocean, contains many small glaciers, in addition to large ice caps. The glaciers on Iceland are particularly sensitive to variations in oceanic and atmospheric circulation (Andresen et al. 2005; GeirsdĂłttir et al., 2009; ĂlafsdĂłttir et al. 2010). Iceland thus provides an excellent case study to examine factors influencing glacial landforms such as cirques. (excerpt
Civic Community Theory and Rates of Violence: A Review of Literature on an Emergent Theoretical Perspective
Civic community theory has emerged in the last 10 years as a middle range theory to explain community variation in rates of crime. It has proven to be particularly powerful for explaining variations in violent crime across rural communities in the U.S. This essay provides a review of the available published literature testing components of the theory. The three main conceptual dimensions of the civic community thesis are outlined, and the nature of the empirical evidence is evaluated. The essay concludes with several suggestions for future research
Stellar Populations and Star Cluster Formation in Interacting Galaxies with the Advanced Camera for Surveys
Pixel-by-pixel colour-magnitude and colour-colour diagrams - based on a
subset of the Hubble Space Telescope Advanced Camera for Surveys Early Release
Observations - provide a powerful technique to explore and deduce the star and
star cluster formation histories of the Mice and the Tadpole interacting
galaxies. In each interacting system we find some 40 bright young star clusters
(20 <= F606W (mag) <= 25, with a characteristic mass of ~3 x 10^6 Msun), which
are spatially coincident with blue regions of active star formation in their
tidal tails and spiral arms. We estimate that the main events triggering the
formation of these clusters occurred ~(1.5-2.0) x 10^8 yr ago. We show that
star cluster formation is a major mode of star formation in galaxy
interactions, with >= 35% of the active star formation in encounters occurring
in star clusters. This is the first time that young star clusters have been
detected along the tidal tails in interacting galaxies. The tidal tail of the
Tadpole system is dominated by blue star forming regions, which occupy some 60%
of the total area covered by the tail and contribute ~70% of the total flux in
the F475W filter (decreasing to ~40% in F814W). The remaining pixels in the
tail have colours consistent with those of the main disk. The tidally triggered
burst of star formation in the Mice is of similar strength in both interacting
galaxies, but it has affected only relatively small, spatially coherent areas.Comment: 23 pages in preprint form, 6 (encapsulated) postscript figures;
accepted for publication in New Astronomy; ALL figures (even the grey-scale
ones) need to be printed on a colour printer style files included; for
full-resolution paper, see http://www.ast.cam.ac.uk/STELLARPOPS/ACSpaper
A Millimeter-scale Single Charged Particle Dosimeter for Cancer Radiotherapy
This paper presents a millimeter-scale CMOS 6464 single charged
particle radiation detector system for external beam cancer radiotherapy. A
11 diode measures energy deposition by a single charged
particle in the depletion region, and the array design provides a large
detection area of 512512 . Instead of sensing the voltage drop
caused by radiation, the proposed system measures the pulse width, i.e., the
time it takes for the voltage to return to its baseline. This obviates the need
for using power-hungry and large analog-to-digital converters. A prototype ASIC
is fabricated in TSMC 65 nm LP CMOS process and consumes the average static
power of 0.535 mW under 1.2 V analog and digital power supply. The
functionality of the whole system is successfully verified in a clinical 67.5
MeV proton beam setting. To our' knowledge, this is the first work to
demonstrate single charged particle detection for implantable in-vivo
dosimetry
Interactions Between Spermine-Derivatized Tentacle Porphyrins And The Human Telomeric DNA G-Quadruplex
G-rich DNA sequences have the potential to fold into non-canonical G-Quadruplex (GQ) structures implicated in aging and human diseases, notably cancers. Because stabilization of GQs at telomeres and oncogene promoters may prevent cancer, there is an interest in developing small molecules that selectively target GQs. Herein, we investigate the interactions of meso-tetrakis-(4-carboxysperminephenyl)porphyrin (TCPPSpm4) and its Zn(II) derivative (ZnTCPPSpm4) with human telomeric DNA (Tel22) via UV-Vis, circular dichroism (CD), and fluorescence spectroscopies, resonance light scattering (RLS), and fluorescence resonance energy transfer (FRET) assays. UV-Vis titrations reveal binding constants of 4.7 Ă 10ⶠand 1.4 Ă 10â· Mâ»Âč and binding stoichiometry of 2â4:1 and 10â12:1 for TCPPSpm4 and ZnTCPPSpm4, respectively. High stoichiometry is supported by the Job plot data, CD titrations, and RLS data. FRET melting indicates that TCPPSpm4 stabilizes Tel22 by 36 ± 2 °C at 7.5 eq., and that ZnTCPPSpm4 stabilizes Tel22 by 33 ± 2 °C at ~20 eq.; at least 8 eq. of ZnTCPPSpm4 are required to achieve significant stabilization of Tel22, in agreement with its high binding stoichiometry. FRET competition studies show that both porphyrins are mildly selective for human telomeric GQ vs duplex DNA. Spectroscopic studies, combined, point to end-stacking and porphyrin self-association as major binding modes. This work advances our understanding of ligand interactions with GQ DNA
Type 1 diabetes in very young children: a model of parent and child influences on management and outcomes
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135479/1/pedi12351.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/135479/2/pedi12351_am.pd
Atomic arrangement and mechanical properties of chemical vapor deposited amorphous boron
Amorphous boron fiber has been widely used as a reinforcement filler in aerospace resin-matrix composites due to its high strength and high elastic modulus. However, its mechanical properties have not been measured accurately due to intrinsic issues during fabrication. Amorphous boron is most commonly produced in singlefilament reactors by chemical vapor deposition of boron on tungsten wire, and the final product is a core-shell wire with a tungsten boride core and amorphous boron shell. Traditionally, wire tension tests of the composite fiber or hollow amorphous boron fiber have been conducted but this method would underestimate the strength due to the greater probability of defects along the long wire. Micropillar compression and tension testing enable us to determine mechanical properties of small materials accurately. In addition, the local atomic arrangement in amorphous boron has not been clearly understood because of the complexity in its amorphous structure. Therefore, it is necessary to conduct advanced transmission electron microscopy (TEM) to analyze the local structure at atomic resolution.
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Genome editing for inborn errors of metabolism: advancing towards the clinic
Abstract
Inborn errors of metabolism (IEM) include many disorders for which current treatments aim to ameliorate disease manifestations, but are not curative. Advances in the field of genome editing have recently resulted in the in vivo correction of murine models of IEM. Site-specific endonucleases, such as zinc-finger nucleases and the CRISPR/Cas9 system, in combination with delivery vectors engineered to target disease tissue, have enabled correction of mutations in disease models of hemophilia B, hereditary tyrosinemia type I, ornithine transcarbamylase deficiency, and lysosomal storage disorders. These in vivo gene correction studies, as well as an overview of genome editing and future directions for the field, are reviewed and discussed herein
Individual and Collective Dimensions of Resilience within Political Violence
Research has documented a link between political violence and the functioning of individuals and communities. Yet, despite the hardships that political violence creates, evidence suggests remarkable fortitude and resilience within both individuals and communities. Individual characteristics that appear to build resilience against political violence include demographic factors such as gender and age, and internal resources such as hope, optimism, determination and religious convictions. Research has also documented the protective influence of individualsâ connection to community and their involvement in work, school or political action. Additionally, research on political violence and resilience has increasingly focused on communities themselves as a unit of analysis. Community resilience, like individual resilience, is a process supported by various traits, capacities, and emotional orientations towards hardship. This review addresses various findings related to both individual and community resilience within political violence and offers recommendations for research, practice, and policy
Individual and Collective Dimensions of Resilience within Political Violence
Research has documented a link between political violence and the functioning of individuals and communities. Yet, despite the hardships that political violence creates, evidence suggests remarkable fortitude and resilience within both individuals and communities. Individual characteristics that appear to build resilience against political violence include demographic factors such as gender and age, and internal resources such as hope, optimism, determination and religious convictions. Research has also documented the protective influence of individualsâ connection to community and their involvement in work, school or political action. Additionally, research on political violence and resilience has increasingly focused on communities themselves as a unit of analysis. Community resilience, like individual resilience, is a process supported by various traits, capacities, and emotional orientations towards hardship. This review addresses various findings related to both individual and community resilience within political violence and offers recommendations for research, practice, and policy
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