149 research outputs found
The Turbulence Power Spectrum in Optically Thick Interstellar Clouds
The Fourier power spectrum is one of the most widely used statistical tools
to analyze the nature of magnetohydrodynamic turbulence in the interstellar
medium. Lazarian & Pogosyan (2004) predicted that the spectral slope should
saturate to -3 for an optically thick medium and many observations exist in
support of their prediction. However, there have not been any numerical studies
to-date testing these results. We analyze the spatial power spectrum of MHD
simulations with a wide range of sonic and Alfv\'enic Mach numbers, which
include radiative transfer effects of the CO transition. We confirm
numerically the predictions of Lazarian & Pogosyan (2004) that the spectral
slope of line intensity maps of an optically thick medium saturates to -3.
Furthermore, for very optically thin supersonic CO gas, where the density or CO
abundance values are too low to excite emission in all but the densest shock
compressed gas, we find that the spectral slope is shallower than expected from
the column density. Finally, we find that mixed optically thin/thick CO gas,
which has average optical depths on order of unity, shows mixed behavior: for
super-Alfv\'enic turbulence, the integrated intensity power spectral slopes
generally follow the same trend with sonic Mach number as the true column
density power spectrum slopes. However, for sub-Alfv\'enic turbulence the
spectral slopes are steeper with values near -3 which are similar to the very
optically thick regime.Comment: accepted to Ap
Authors' Reply to Coste et al.: "Levothyrox® New and Old Formulations: Are they Switchable for Millions of Patients?"
"Authors'Reply to Coste et al"International audienc
In vivo and in vitro synthesis of CM-proteins (A-hordeins) from barley (Hordeum vulgare L.)
CM-proteins from barley endosperm (CMa, CMb, CMc, CMd), which are the main components of the A-hordein fraction, are synthesized most actively 10 to 30 d after anthesis (maximum at 15–20 d). They are synthesized by membranebound polysomes as precursors of higher apparent molecular weight (13,000–21,000) than the mature proteins (12,000–16,000). The largest in vitro product (21,000) is the putative precursor of protein CMd (16,000), as it is selected with anti-CMd monospecific IgG's, and is coded by an mRNA of greater sedimentation coefficient (9 S) than those encoding the other three proteins (7.5 S). CM-proteins always appear in the soluble fraction, following different homogenization and subcellular fractionation procedures, indicating that these proteins are transferred to the soluble fraction after processing
The Simons Observatory: Galactic Science Goals and Forecasts
Observing in six frequency bands from 27 to 280 GHz over a large sky area,
the Simons Observatory (SO) is poised to address many questions in Galactic
astrophysics in addition to its principal cosmological goals. In this work, we
provide quantitative forecasts on astrophysical parameters of interest for a
range of Galactic science cases. We find that SO can: constrain the frequency
spectrum of polarized dust emission at a level of
and thus test models of dust composition that predict that in
polarization differs from that measured in total intensity; measure the
correlation coefficient between polarized dust and synchrotron emission with a
factor of two greater precision than current constraints; exclude the
non-existence of exo-Oort clouds at roughly 2.9 if the true fraction is
similar to the detection rate of giant planets; map more than 850 molecular
clouds with at least 50 independent polarization measurements at 1 pc
resolution; detect or place upper limits on the polarization fractions of
CO(2-1) emission and anomalous microwave emission at the 0.1% level in select
regions; and measure the correlation coefficient between optical starlight
polarization and microwave polarized dust emission in patches for all
lines of sight with cm. The goals and
forecasts outlined here provide a roadmap for other microwave polarization
experiments to expand their scientific scope via Milky Way astrophysics.Comment: Submitted to AAS journals. 33 pages, 10 figure
Quantification of endogenous levels of IAA, IAAsp and IBA in micro-propagated shoots of hybrid chestnut pre-treated with IBA
Endogenous levels of indole-3-acetic acid (IAA),
indole-3-acetylaspartic acid (IAAsp) and indole-3-butyric
acid (IBA) were measured during the first 8 d of in vitro
rooting of rootstock from the chestnut ‘M3’ hybrid by high
performance liquid chromatography (HPLC). Rooting was
induced either by dipping the basal ends of the shoots into a
4.92-mM IBA solution for 1 min or by sub-culturing the
shoots on solid rooting medium supplemented with 14.8-
μM IBA for 5 d. For root development, the induced shoots
were transferred to auxin-free solid medium. Auxins were
measured in the apical and basal parts of the shoots by
means of HPLC. Endogenous levels of IAA and IAAsp
were found to be greater in IBA-treated shoots than in
control shoots. In extracts of the basal parts of the shoots,
the concentration of free IAA showed a significant peak 2 d
after either root inductive method and a subsequent gradual
decrease for the remainder of the time course. The
concentration of IAAsp peaked at day 6 in extracts of the
basal parts of shoots induced with 14.8-μM IBA for 5 d,
whereas shoots induced by dipping showed an initial
increase until day 2 and then remained stable. In extracts
from basal shoot portions induced by dipping, IBA
concentration showed a transient peak at day 1 and a plateau between day 2 and 4, in contrast to the profile of
shoots induced on auxin-containing medium, which
showed a significant reduction between 4 and 6 d after
transferred to auxin-free medium. All quantified auxins
remained at a relatively low level, virtually constant, in
extracts from apical shoot portions, as well as in extracts
from control non-rooting shoots. In conclusion, the natural
auxin IAA is the signal responsible for root induction,
although it is driven by exogenous IBA independently of
the adding conditions
Living on the edge: utilising lidar data to assess the importance of vegetation structure for avian diversity in fragmented woodlands and their edges
Context: In agricultural landscapes, small woodland patches can be important wildlife refuges. Their value in maintaining biodiversity may, however, be compromised by isolation, and so knowledge about the role of habitat structure is vital to understand the drivers of diversity. This study examined how avian diversity and abundance were related to habitat structure in four small woods in an agricultural landscape in eastern England. Objectives: The aims were to examine the edge effect on bird diversity and abundance, and the contributory role of vegetation structure. Specifically: what is the role of vegetation structure on edge effects, and which edge structures support the greatest bird diversity? Methods: Annual breeding bird census data for 28 species were combined with airborne lidar data in linear mixed models fitted separately at (i) the whole wood level, and (ii) for the woodland edges only. Results: Despite relatively small woodland areas (4.9–9.4 ha), bird diversity increased significantly towards the edges, being driven in part by vegetation structure. At the whole woods level, diversity was positively associated with increased vegetation above 0.5 m and especially with increasing vegetation density in the understorey layer, which was more abundant at the woodland edges. Diversity along the edges was largely driven by the density of vegetation below 4 m. Conclusions: The results demonstrate that bird diversity was maximised by a diverse vegetation structure across the wood and especially a dense understorey along the edge. These findings can assist bird conservation by guiding habitat management of remaining woodland patches
Lineage-specific evolution of the vertebrate Otopetrin gene family revealed by comparative genomic analyses
Background: Mutations in the Otopetrin 1 gene (Otop1) in mice and fish produce an unusual bilateral vestibular pathology that involves the absence of otoconia without hearing impairment. The encoded protein, Otop1, is the only functionally characterized member of the Otopetrin Domain Protein (ODP) family; the extended sequence and structural preservation of ODP proteins in metazoans suggest a conserved functional role. Here, we use the tools of sequence-and cytogenetic-based comparative genomics to study the Otop1 and the Otop2-Otop3 genes and to establish their genomic context in 25 vertebrates. We extend our evolutionary study to include the gene mutated in Usher syndrome (USH) subtype 1G (Ush1g), both because of the head-to-tail clustering of Ush1g with Otop2 and because Otop1 and Ush1g mutations result in inner ear phenotypes. Results: We established that OTOP1 is the boundary gene of an inversion polymorphism on human chromosome 4p16 that originated in the common human-chimpanzee lineage more than 6 million years ago. Other lineage-specific evolutionary events included a three-fold expansion of the Otop genes in Xenopus tropicalis and of Ush1g in teleostei fish. The tight physical linkage between Otop2 and Ush1g is conserved in all vertebrates. To further understand the functional organization of the Ushg1-Otop2 locus, we deduced a putative map of binding sites for CCCTC-binding factor (CTCF), a mammalian insulator transcription factor, from genome-wide chromatin immunoprecipitation-sequencing (ChIP-seq) data in mouse and human embryonic stem (ES) cells combined with detection of CTCF-binding motifs. Conclusions: The results presented here clarify the evolutionary history of the vertebrate Otop and Ush1g families, and establish a framework for studying the possible interaction(s) of Ush1g and Otop in developmental pathways
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