313 research outputs found
Soft Carrier Multiplications by Hot Electrons in Graphene
By using Boltzmann formalism, we show that carrier multiplication by impact
ionization can take place at relatively low electric fields during electronic
transport in graphene. Because of the absence of energy gap, this effect is not
characterized by a field threshold unlike in conventional semiconductors, but
is a quadratic function of the electric field. We also show that the resulting
current is an increasing function of the electronic temperature, but decreases
with increasing carrier concentration
Establishing the impact of luminous AGN with multi-wavelength observations and simulations
Cosmological simulations fail to reproduce realistic galaxy populations
without energy injection from active galactic nuclei (AGN) into the
interstellar medium (ISM) and circumgalactic medium (CGM); a process called
`AGN feedback'. Consequently, observational work searches for evidence that
luminous AGN impact their host galaxies. Here, we review some of this work.
Multi-phase AGN outflows are common, some with potential for significant
impact. Additionally, multiple feedback channels can be observed
simultaneously; e.g., radio jets from `radio quiet' quasars can inject
turbulence on ISM scales, and displace CGM-scale molecular gas. However,
caution must be taken comparing outflows to simulations (e.g., kinetic coupling
efficiencies) to infer feedback potential, due to a lack of comparable
predictions. Furthermore, some work claims limited evidence for feedback
because AGN live in gas-rich, star-forming galaxies. However, simulations do
not predict instantaneous, global impact on molecular gas or star formation.
The impact is expected to be cumulative, over multiple episodes.Comment: Accepted for publication in IAU Symposium 378 Conference Proceedings
"Black Hole Winds at all Scales
Improvement of Grazing Lands for Better Livestock Production--A Case Study from Chitradurga District in India
Chitradurga is a highly drought prone district in the central dry zone of Karnataka, India, with a normal rainfall of 530 mm per annum. Over 85 per cent of cultivable area is rainfed and the livestock plays a vital role in rural income generation in this district. Improper management and overgrazing have resulted in most of the grazing resources declining to a poor, degraded condition. Regeneration of pasture land was vital in the villages due to three reasons - a) people\u27s livelihood dependency on livestock was considerable b) small ruminants played a vital role for landless farmers and c) lack of adequate fodder was a prime factor for low livestock productivity. To improve the livelihood of livestock farmers, a few interventions were made under World Bank funded National Agricultural Innovation Project through consortium approach in 10 project villages. Frequent interactions were held with the local livestock farmers to discuss about the importance of increasing the fodder resources in the villages to improve the income and to sustain their livelihood. They realized the importance of fodder and came forward to take up cultivation of perennial fodders and also, for the revitalization of grazing lands, locally known as kavals. The primary survey in the villages indicated that about 90 to 96 per cent of the small ruminant holders are dependent on these common property grazing resources for the fodder needs. The High Level Panel of Experts on food security and nutrition, constituted by FAO, has emphasized the importance of extending appropriate technologies and inputs, providing the needed credit and ensuring assured and remunerative marketing opportunities to the smallholders (HLPE, 2013). Such measures are also essential for revitalizing the degraded grasslands in this region
Dissolution Potentials of Sodium & Potassium Chlorides, Bromides & Iodides & of Ammonium Halides
561-56
An acridine derivative, [4,5-bis{(N-carboxy methyl imidazolium)methyl}acridine] dibromide, shows anti-TDP-43 aggregation effect in ALS disease models
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease associated with aggregation of TAR DNA-binding protein-43 (TDP-43) in neuronal cells and manifests as motor neuron dysfunction & muscle atrophy. The carboxyl-terminal prion-like domain of TDP-43 can aggregate in vitro into toxic β-sheet rich amyloid-like structures. So far, treatment options for ALS are very limited and Riluzole, which targets glutamate receptors, is the only but highly ineffective drug. Therefore, great interest exists in developing molecules for ALS treatment. Here, we have examined certain derivatives of acridine containing same side chains at position 4 & 5, for inhibitory potential against TDP-43 aggregation. Among several acridine derivatives examined, AIM4, which contains polar carboxyl groups in the side arms, significantly reduces TDP-43-YFP aggregation in the powerful yeast model cell and also abolishes in vitro amyloid-like aggregation of carboxyl terminal domain of TDP-43, as observed by AFM imaging. Thus, AIM4 can be a lead molecule potentiating further therapeutic research for ALS
A Protocol of Using White/Red Color Assay to Measure Amyloid-induced Oxidative Stress in Saccharomyces cerevisiae
The yeast Saccharomyces cerevisiae (S. cerevisiae) harboring ade1 or ade2 mutations manifest red colony color phenotype on rich yeast medium YPD. In these mutants, intermediate metabolites of adenine biosynthesis pathway are accumulated. Accumulated intermediates, in the presence of reduced glutathione, are transported to the vacuoles, whereupon the development of the red color phenotype occurs. Here, we describe a method to score for presence of oxidative stress upon expression of amyloid-like proteins that would convert the red phenotype of ade1/ade2 mutant yeast to white. This assay could be a useful tool for screening for drugs with anti-amyloid aggregation or anti-oxidative stress potency
Learning Free-Form Deformations for 3D Object Reconstruction
Representing 3D shape in deep learning frameworks in an accurate, efficient
and compact manner still remains an open challenge. Most existing work
addresses this issue by employing voxel-based representations. While these
approaches benefit greatly from advances in computer vision by generalizing 2D
convolutions to the 3D setting, they also have several considerable drawbacks.
The computational complexity of voxel-encodings grows cubically with the
resolution thus limiting such representations to low-resolution 3D
reconstruction. In an attempt to solve this problem, point cloud
representations have been proposed. Although point clouds are more efficient
than voxel representations as they only cover surfaces rather than volumes,
they do not encode detailed geometric information about relationships between
points. In this paper we propose a method to learn free-form deformations (FFD)
for the task of 3D reconstruction from a single image. By learning to deform
points sampled from a high-quality mesh, our trained model can be used to
produce arbitrarily dense point clouds or meshes with fine-grained geometry. We
evaluate our proposed framework on both synthetic and real-world data and
achieve state-of-the-art results on point-cloud and volumetric metrics.
Additionally, we qualitatively demonstrate its applicability to label
transferring for 3D semantic segmentation.Comment: 16 pages, 7 figures, 3 table
Inspecting spectra with sound: proof-of-concept & extension to datacubes
We present a novel approach to inspecting galaxy spectra using sound, via
their direct audio representation ('spectral audification'). We discuss the
potential of this as a complement to (or stand-in for) visual approaches. We
surveyed 58 respondents who use the audio representation alone to rate 30
optical galaxy spectra with strong emission lines. Across three tests, each
focusing on different quantities measured from the spectra (signal-to-noise
ratio, emission-line width, & flux ratios), we find that user ratings are well
correlated with measured quantities. This demonstrates that physical
information can be independently gleaned from listening to spectral
audifications. We note the importance of context when rating these
sonifications, where the order examples are heard can influence responses.
Finally, we adapt the method used in this promising pilot study to spectral
datacubes. We suggest that audification allows efficient exploration of
complex, spatially-resolved spectral data.Comment: 6 pages, 3 figures, accepted for publication in RASTI. Supplementary
data (including animated figure) available at
https://doi.org/10.25405/data.ncl.2281644
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