3,846 research outputs found
Experimental phase functions of mm-sized cosmic dust grains
We present experimental phase functions of three types of millimeter-sized
dust grains consisting of enstatite, quartz and volcanic material from Mount
Etna, respectively. The three grains present similar sizes but different
absorbing properties. The measurements are performed at 527 nm covering the
scattering angle range from 3 to 170 degrees. The measured phase functions show
two well defined regions i) soft forward peaks and ii) a continuous increase
with the scattering angle at side- and back-scattering regions. This behavior
at side- and back-scattering regions are in agreement with the observed phase
functions for the Fomalhaut and HR 4796A dust rings. Further computations and
measurements (including polarization) for millimeter sized-grains are needed to
draw some conclusions about the fluffy or compact structure of the dust grains
Enhanced transmission through arrays of subwavelength holes in gold films coated by a finite dielectric layer
Enhanced transmissions through a gold film with arrays of subwavelength holes
are theoretically studied, employing the rigid full vectorial three dimensional
finite difference time domain method. Influence of air-holes shape to the
transmission is firstly studied, which confirms two different resonances
attributing to the enhanced transmission: the localized waveguide resonance and
periodic surface plasmon resonances. For the film coated with dielectric
layers, calculated results show that in the wavelength region of interest the
localized waveguide resonant mode attributes to sensing rather than the
periodic gold-glass surface plasmon mode. Although the detected peak is fairly
broad and the shift is not too pronounced, we emphasize the contribution for
sensing from the localized waveguide resonant mode, which may opens up new ways
to design surface plasmon based sensors.Comment: 11 pages including 4 figures. Accepted for JEOS:R
The shape and composition of interstellar silicate grains
We investigate the composition and shape distribution of silicate dust grains
in the interstellar medium. The effect of the amount of magnesium in the
silicate lattice is studied. We fit the spectral shape of the interstellar 10
mu extinction feature as observed towards the galactic center. We use very
irregularly shaped coated and non-coated porous Gaussian Random Field particles
as well as a statistical approach to model shape effects. For the dust
materials we use amorphous and crystalline silicates with various composition
and SiC. The results of our analysis of the 10 mu feature are used to compute
the shape of the 20 mu silicate feature and to compare this with observations.
By using realistic particle shapes we are, for the first time, able to derive
the magnesium fraction in interstellar silicates. We find that the interstellar
silicates are highly magnesium rich (Mg/(Fe+Mg)>0.9) and that the stoichiometry
lies between pyroxene and olivine type silicates. This composition is not
consistent with that of the glassy material found in GEMS in interplanetary
dust particles indicating that these are, in general, not unprocessed remnants
from the interstellar medium. Also, we find a significant fraction of SiC
(~3%). We discuss the implications of our results for the formation and
evolutionary history of cometary and circumstellar dust. We argue that the fact
that crystalline silicates in cometary and circumstellar grains are almost
purely magnesium silicates is a natural consequence of our findings that the
amorphous silicates from which they were formed were already magnesium rich.Comment: Accepted for publication in A&
Distance Between External Cortical Bone and Mandibular Canal for Harvesting Ramus Graft: A Human Cadaver Study
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141448/1/jper0239.pd
Letter to the Editor: Authors’ Response
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141156/1/jper1104.pd
Active control of focal length and beam deflection in a metallic nano-slit array lens with multiple sources
We propose a surface plasmon-polariton based nano-rod array lens structure
that incorporates two additional lateral input channels, with the ability to
control the focal length and the deflection of the transmitted beam through the
lens actively by the intensity of the channel sources. We demonstrate by
numerical simulations that, applying the sources with the same intensity can
change the focal point and the beam waist, whereas unequal intensities generate
an asymmetric field profile in the nano-rod array inducing an off-axis beam
deflection.Comment: 4 pages, 5 figure
2-Isopropoxyphenyl N-methylcarbamate
In the title compound, C11H15NO3, the mean planes of the carboxamide and isopropyl groups are inclined at 109.9 (1) and 128.7 (2)°, respectively, to the mean plane of the phenoxy group. In the crystal structure, molecules are stacked along the b axis, without any π–π interactions. The stacked columns are linked together by intermolecular N—H⋯O hydrogen bonds, with an N⋯O distance of 2.842 (2) Å
Molecular basis for SMC rod formation and its dissolution upon DNA binding.
SMC condensin complexes are central modulators of chromosome superstructure in all branches of life. Their SMC subunits form a long intramolecular coiled coil, which connects a constitutive "hinge" dimerization domain with an ATP-regulated "head" dimerization module. Here, we address the structural arrangement of the long coiled coils in SMC complexes. We unequivocally show that prokaryotic Smc-ScpAB, eukaryotic condensin, and possibly also cohesin form rod-like structures, with their coiled coils being closely juxtaposed and accurately anchored to the hinge. Upon ATP-induced binding of DNA to the hinge, however, Smc switches to a more open configuration. Our data suggest that a long-distance structural transition is transmitted from the Smc head domains to regulate Smc-ScpAB's association with DNA. These findings uncover a conserved architectural theme in SMC complexes, provide a mechanistic basis for Smc's dynamic engagement with chromosomes, and offer a molecular explanation for defects in Cornelia de Lange syndrome
Lower urinary tract and bowel dysfunction in spinocerebellar ataxias
Background: Little information is available in spinocerebellar ataxias (SCAs)
regarding pelvic organ symptoms. The aim of this study was to characterize the
lower urinary tract (LUT) and bowel dysfunction in autosomal dominant
spinocerebellar ataxias. Methods: Patients with confirmed SCAs attending a tertiary care service were approached about LUT and bowel complaints, and completed validated questionnaires: urinary symptom profile (USP), QualiveenShort form, International Prostate Symptom Score, and Neurogenic Bowel Dysfunction Score. SCA3 and SCA7 patients with urological complaints additionally underwent urodynamic studies (UDS). Patients’ characterization included
demographic, clinical (Scale for the Assessment and Rating of Ataxia (SARA),
Inventory of Non-Ataxia Signs (INAS)), and genetic variables. Descriptive and
comparative analyses were performed. Results: Fifty-one patients participated:
SCA1 (n = 4), SCA2 (n = 11), SCA3 (n = 13), SCA6 (n = 17), and SCA7
(n = 6). The prevalence of self-reported LUT symptoms was 60.8% (n = 31),
whereas LUT symptoms was reported in 86.3%(n = 44) using the USP. Both
storage and voiding symptoms were reported, urinary frequency and urgency
being the most frequent (n = 34, 68%). Although LUT symptoms were most
often classed as mild (n = 27, 61.4%), they impacted QoL in 38 patients
(77.6%). Of these, 21 (55.3%) were not on pharmacological treatment for urinary dysfunction. Most common abnormalities in UDS (n = 14) were detrusor
overactivity (storage phase) and detrusor underactivity (voiding phase). Bowel
symptoms were less common (31.4%, n = 16) and of mild severity. Conclusion: LUT symptoms are prevalent in SCA patients and impact QoL, whereas
bowel symptoms tend to be mild. These symptoms are overlooked by patients
and physicians due to the complexity of neurological involvement in SCA, and
therefore a multidisciplinary management approach should be adopted
The sequence selectivity of KSRP explains its flexibility in the recognition of the RNA targets
K-homology (KH) splicing regulator protein (KSRP) is a multi-domain RNA-binding protein that regulates different steps of mRNA metabolism, from mRNA splicing to mRNA decay, interacting with a broad range of RNA sequences. To understand how KSRP recognizes its different RNA targets it is necessary to define the general rules of KSRP–RNA interaction. We describe here a complete scaffold-independent analysis of the RNA-binding potential of the four KH domains of KSRP. The analysis shows that KH3 binds to the RNA with a significantly higher affinity than the other domains and recognizes specifically a G-rich target. It also demonstrates that the other KH domains of KSRP display different sequence preferences explaining the broad range of targets recognized by the protein. Further, KSRP shows a strong negative selectivity for sequences containing several adjacent Cytosines limiting the target choice of KSRP within single-stranded RNA regions. The in-depth analysis of the RNA-binding potential of the KH domains of KSRP provides us with an understanding of the role of low sequence specificity domains in RNA recognition by multi-domain RNA-binding proteins
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