343 research outputs found
Studies on the Effects of Ammonium Phosphates on the Flammability Properties of Poly(Vinyl Alcohol) Films
Poly(vinyl alcohol) was solvent-cast from aqueous solution of n-hexane into 125 μm films. Three ammonium phosphates, (NH4)3PO4, NH4H2PO4 and (NH4)2HPO4, were then added to produce eight sample films. Burning time, flame spread, limiting oxygen index, ignition time, and afterglow time of the samples were evaluated to determine the flame retardant efficiency of the three fillers. From the results, burning time, flame spread, after-glow time, and ignition response indices of the filled samples were found to be lower than the control sample. However, limiting oxygen index of the filled samples was found to be higher than that of the control sample. The efficiency of the fillers in fireproofing the poly(vinyl alcohol) film was found to follow the order (NH4)3PO4 > NH4H2PO4 > (NH4)2HPO4. Additive effect was observed when the fillers are added in pairs with the fireproofing efficiency following the order (NH4)3PO4 + NH4H2PO4 > (NH4)3PO4 + (NH4)2HPO4 > (NH4)2HPO4 + NH4H2PO4. Antagonism in fireproofing efficiency was observed when all the three fillers were present in the poly(vinyl alcohol) film. The fireproofing efficiency of the ammonium salts is attributed to the quantity and the ease with which ammonia (NH3) gas is released when the filled poly(vinyl alcohol) films were heated
A Case of Bifid Mandibular Condyle
Bifid mandibular condyle is a rare anatomic anomaly that can result from congenital malformation, trauma, infection or tumor. We report a case of bifid mandibular condyle found after head injury. A bifid mandibular condyle was seen on the computed tomographic scan of a 41-year-old man after a car accident. The patient had asymmetry in the condylar angle and length of the condylar neck, and anomaly of occlusion resulting from many residual roots with deep caries. Mouth-opening and mandibular movements were normal, however, the presence of temporomandibular joint symptoms was unclear because of the patient’s unconsciousness at the time of the scan. The bifid mandibular condyle could have resulted from a bicycle accident when the patient was 7 years of age, based on information from the patient’s family.Isomura ET, Kobashi H, Tanaka S, Enomoto A, Kogo M (2017) A Case of Bifid Mandibular Condyle. OMICS J Radiol 6: 278. DOI: 10.4172/2167-7964.1000278
Reconstructing the Primordial Spectrum with CMB Temperature and Polarization
We develop a new method to reconstruct the power spectrum of primordial
curvature perturbations, , by using both the temperature and polarization
spectra of the cosmic microwave background (CMB). We test this method using
several mock primordial spectra having non-trivial features including the one
with an oscillatory component, and find that the spectrum can be reconstructed
with a few percent accuracy by an iterative procedure in an ideal situation in
which there is no observational error in the CMB data. In particular, although
the previous ``cosmic inversion'' method, which used only the temperature
fluctuations, suffered from large numerical errors around some specific values
of that correspond to nodes in a transfer function, these errors are found
to disappear almost completely in the new method.Comment: 18 pages, 17 figures, submitted to PR
Reconstructing the primordial power spectrum - a new algorithm
We propose an efficient and model independent method for reconstructing the
primordial power spectrum from Cosmic Microwave Background (CMB) and large
scale structure observations. The algorithm is based on a Monte Carlo principle
and therefore very simple to incorporate into existing codes such as Markov
Chain Monte Carlo. The algorithm has been used on present cosmological data to
test for features in the primordial power spectrum. No significant evidence for
features is found, although there is a slight preference for an overall bending
of the spectrum, as well as a decrease in power at very large scales. We have
also tested the algorithm on mock high precision CMB data, calculated from
models with non-scale invariant primordial spectra. The algorithm efficiently
extracts the underlying spectrum, as well as the other cosmological parameters
in each case. Finally we have used the algorithm on a model where an artificial
glitch in the CMB spectrum has been imposed, like the ones seen in the WMAP
data. In this case it is found that, although the underlying cosmological
parameters can be extracted, the recovered power spectrum can show significant
spurious features, such as bending, even if the true spectrum is scale
invariant.Comment: 22 pages, 12 figures, matches JCAP published versio
Cosmology with CMB anisotropy
Measurements of CMB anisotropy and, more recently, polarization have played a
very important role allowing precise determination of various parameters of the
`standard' cosmological model. The expectation of the paradigm of inflation and
the generic prediction of the simplest realization of inflationary scenario in
the early universe have also been established -- `acausally' correlated initial
perturbations in a flat, statistically isotropic universe, adiabatic nature of
primordial density perturbations. Direct evidence for gravitational instability
mechanism for structure formation from primordial perturbations has been
established. In the next decade, future experiments promise to strengthen these
deductions and uncover the remaining crucial signature of inflation -- the
primordial gravitational wave background.Comment: Plenary talk at the IXth. International Workshop on High Energy
Physics Phenomenology (WHEPP-9), Institute of Physics, Bhubaneshwar, India.
Jan 3-14, 2006; To appear in the Proceedings to be published in Pramana; 12
pages, 2 figure
`Standard' Cosmological model & beyond with CMB
Observational Cosmology has indeed made very rapid progress in the past
decade. The ability to quantify the universe has largely improved due to
observational constraints coming from structure formation Measurements of CMB
anisotropy and, more recently, polarization have played a very important role.
Besides precise determination of various parameters of the `standard'
cosmological model, observations have also established some important basic
tenets that underlie models of cosmology and structure formation in the
universe -- `acausally' correlated initial perturbations in a flat,
statistically isotropic universe, adiabatic nature of primordial density
perturbations. These are consistent with the expectation of the paradigm of
inflation and the generic prediction of the simplest realization of
inflationary scenario in the early universe. Further, gravitational instability
is the established mechanism for structure formation from these initial
perturbations. The signature of primordial perturbations observed as the CMB
anisotropy and polarization is the most compelling evidence for new, possibly
fundamental, physics in the early universe. The community is now looking beyond
the estimation of parameters of a working `standard' model of cosmology for
subtle, characteristic signatures from early universe physics.Comment: 16 pages, 6 figures, Plenary talk, Proc. of GR-19, Mexico City,
Mexico (Jul 5-9, 2010). To appear in a special issue in Class. Q. Gra
The lncRNA HOTAIR transcription is controlled by HNF4α-induced chromatin topology modulation
The expression of the long noncoding RNA HOTAIR (HOX Transcript Antisense Intergenic RNA) is largely deregulated in epithelial cancers and positively correlates with poor prognosis and progression of hepatocellular carcinoma and gastrointestinal cancers. Furthermore, functional studies revealed a pivotal role for HOTAIR in the epithelial-to-mesenchymal transition, as this RNA is causal for the repressive activity of the master factor SNAIL on epithelial genes. Despite the proven oncogenic role of HOTAIR, its transcriptional regulation is still poorly understood. Here hepatocyte nuclear factor 4-α (HNF4α), as inducer of epithelial differentiation, was demonstrated to directly repress HOTAIR transcription in the mesenchymal-to epithelial transition. Mechanistically, HNF4α was found to cause the release of a chromatin loop on HOTAIR regulatory elements thus exerting an enhancer-blocking activity
The Snail repressor recruits EZH2 to specific genomic sites through the enrollment of the lncRNA HOTAIR in epithelial-to-mesenchymal transition
The transcription factor Snail is a master regulator of cellular identity and epithelial-to-mesenchymal transition (EMT) directly repressing a broad repertoire of epithelial genes. How chromatin modifiers instrumental to its activity are recruited to Snail-specific binding sites is unclear. Here we report that the long non-coding RNA (lncRNA) HOTAIR (for HOX Transcript Antisense Intergenic RNA) mediates a physical interaction between Snail and enhancer of zeste homolog 2 (EZH2), an enzymatic subunit of the polycomb-repressive complex 2 and the main writer of chromatin-repressive marks. The Snail-repressive activity, here monitored on genes with a pivotal function in epithelial and hepatic morphogenesis, differentiation and cell-type identity, depends on the formation of a tripartite Snail/HOTAIR/EZH2 complex. These results demonstrate an lncRNA-mediated mechanism by which a transcriptional factor conveys a general chromatin modifier to specific genes, thereby allowing the execution of hepatocyte transdifferentiation; moreover, they highlight HOTAIR as a crucial player in the Snail-mediated EMT.Oncogene advance online publication, 25 July 2016; doi:10.1038/onc.2016.260
Targeted deletion of the C-terminus of the mouse adenomatous polyposis coli tumor suppressor results in neurologic phenotypes related to schizophrenia
Background: Loss of adenomatous polyposis coli (APC) gene function results in constitutive activation of the canonical Wnt pathway and represents the main initiating and rate-limiting event in colorectal tumorigenesis. APC is likely to participate in a wide spectrum of biological functions via its different functional domains and is abundantly expressed in the brain as well as in peripheral tissues. However, the neuronal function of APC is poorly understood. To investigate the functional role of Apc in the central nervous system, we analyzed the neurological phenotypes of Apc 1638T/1638T mice, which carry a targeted deletion of the 3′ terminal third of Apc that does not affect Wnt signaling. Results: A series of behavioral tests revealed a working memory deficit, increased locomotor activity, reduced anxiety-related behavior, and mildly decreased social interaction in Apc 1638T/1638T mice. Apc 1638T/1638T mice showed abnormal morphology of the dendritic spines and impaired long-term potentiation of synaptic transmission in the hippocampal CA1 region. Moreover, Apc 1638T/1638T mice showed abnormal dopamine and serotonin distribution in the brain. Some of these behavioral and neuronal phenotypes are related to symptoms and endophenotypes of schizophrenia. Conclusions: Our results demonstrate that the C-terminus of the Apc tumor suppressor plays a critical role in cognitive and neuropsychiatric functioning. This finding suggests a potential functional link between the C-terminus of APC and pathologies of the central nervous system
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