552 research outputs found
Evolution of E2 transition strength in deformed hafnium isotopes from new measurements on Hf, Hf, and Hf
The available data for E2 transition strengths in the region between
neutron-deficient Hf and Pt isotopes are far from complete. More and precise
data are needed to enhance the picture of structure evolution in this region
and to test state-of-the-art nuclear models. In a simple model, the maximum
collectivity is expected at the middle of the major shell. However, for actual
nuclei, this picture may no longer be the case, and one should use a more
realistic nuclear-structure model. We address this point by studying the
spectroscopy of Hf. We remeasure the 2^+_1 half-lives of 172,174,176Hf, for
which there is some disagreement in the literature. The main goal is to
measure, for the first time, the half-lives of higher-lying states of the
rotational band. The new results are compared to a theoretical calculation for
absolute transition strengths. The half-lives were measured using \gamma-\gamma
and conversion-electron-\gamma delayed coincidences with the fast timing
method. For the determination of half-lives in the picosecond region, the
generalized centroid difference method was applied. For the theoretical
calculation of the spectroscopic properties, the interacting boson model is
employed, whose Hamiltonian is determined based on microscopic energy-density
functional calculations. The measured 2^+_1 half-lives disagree with results
from earlier \gamma-\gamma fast timing measurements, but are in agreement with
data from Coulomb excitation experiments and other methods. Half-lives of the
4^+_1 and 6^+_1 states were measured, as well as a lower limit for the 8^+_1
states. We show the importance of the mass-dependence of effective boson charge
in the description of E2 transition rates in chains of nuclei. It encourages
further studies of the microscopic origin of this mass dependence. New data on
transition rates in nuclei from neighboring isotopic chains could support these
studies.Comment: 16 pages, 16 figures, 7 tables; Abstract shortened due to character
limi
Pulmonary intralobar sequestration
Two cases of pulmonary intralobar sequestration are presented, with aortography and selective arteriography. These examinations are prerequisites for the diagnosis and management of a patient with suspected sequestration. There should be a high degree of suspicion in a case of a persistent left lower-lobe tumour.S. Afr. Med. J., 48, 171 (1974)
Negative regulation of syntaxin4/SNAP-23/VAMP2-mediated membrane fusion by Munc18c <i>In Vitro</i>
Background: Translocation of the facilitative glucose transporter GLUT4 from an intracellular store to the plasma membrane is responsible for the increased rate of glucose transport into fat and muscle cells in response to insulin. This represents a specialised form of regulated membrane trafficking. Intracellular membrane traffic is subject to multiple levels of regulation by conserved families of proteins in all eukaryotic cells. Notably, all intracellular fusion events require SNARE proteins and Sec1p/Munc18 family members. Fusion of GLUT4-containing vesicles with the plasma membrane of insulin-sensitive cells involves the SM protein Munc18c, and is regulated by the formation of syntaxin 4/SNAP23/VAMP2 SNARE complexes. Methodology/Principal Findings Here we have used biochemical approaches to characterise the interaction(s) of Munc18c with its cognate SNARE proteins and to examine the role of Munc18c in regulating liposome fusion catalysed by syntaxin 4/SNAP23/VAMP2 SNARE complex formation. We demonstrate that Munc18c makes contacts with both t- and v-SNARE proteins of this complex, and directly inhibits bilayer fusion mediated by the syntaxin 4/SNAP23/VAMP2 SNARE complex. Conclusion/Significance Our reductionist approach has enabled us to ascertain a direct inhibitory role for Munc18c in regulating membrane fusion mediated by syntaxin 4/SNAP23/VAMP2 SNARE complex formation. It is important to note that two different SM proteins have recently been shown to stimulate liposome fusion mediated by their cognate SNARE complexes. Given the structural similarities between SM proteins, it seems unlikely that different members of this family perform opposing regulatory functions. Hence, our findings indicate that Munc18c requires a further level of regulation in order to stimulate SNARE-mediated membrane fusion
Online Music in China
Nowadays Internet technology allows for music that can either be listened to via streaming or via download on a mobile device. Online music in this report refers to music distributed via Internet or mobile communication. Online music can be divided into two types: the first is music digitalized from traditional albums which is made by professional album companies, and; the second is music directly made in digital form and spread through the Internet. It needs to be pointed out that the majority of Internet music that is listened to is still music made by traditional album companies, and that is also what most websites provide to users. Thus, in this music part, these two types of music will be addressed. From the musicians’ side, the discussion is more about original Internet music; from the users’ side, unless pointed out otherwise, the user experience focusses on both types
Online Film in China
The most recent major sale of a US film company was announced at the beginning of November 2016: “Wanda buys Dick Clark Productions”.1 Who would have predicted this announcement ten years ago? The Chinese Dalian Wanda Group is about to buy Dick Clark Productions for about one billion USD; and with it the broadcasting rights to television programs that attract tens of millions of viewers every year: The Golden Globe Awards, the Academy of Country Music Awards and the New Year countdown celebrations in New York. The latter, with an estimated reach of more than a billion, has become an iconic image of New Year’s Eve festiv- ities
Online literature in China
Online literature is very popular in China today. There, online literature can roughly be divided into two parts. First, there is the literature written by ordinary writers and posted directly on the Internet. Second, there are digitalized versions of existing literature, which are digitalized from traditionally published and printed books. Many books are made into PDF versions or other kinds of digital versions for mobile phones, Kindles, and other reading devices. Many people want to read digitalized copies of printed books simply because the storage devices are much smaller than paper books, and are much easier to be taken everywhere, or because they are more eco-friendly.
In this report, we will mainly discuss the first kind of literature, and call it “internet literature”. Internet literature works are published and printed as paper books after they become very popular, but in this report, we categorize all the works that are firstly re- leased on the Internet as “internet literature”
Structural Disorder Provides Increased Adaptability for Vesicle Trafficking Pathways
Vesicle trafficking systems play essential roles in the communication between the organelles of eukaryotic cells and also
between cells and their environment. Endocytosis and the late secretory route are mediated by clathrin-coated vesicles,
while the COat Protein I and II (COPI and COPII) routes stand for the bidirectional traffic between the ER and the Golgi
apparatus. Despite similar fundamental organizations, the molecular machinery, functions, and evolutionary characteristics
of the three systems are very different. In this work, we compiled the basic functional protein groups of the three main
routes for human and yeast and analyzed them from the structural disorder perspective. We found similar overall disorder
content in yeast and human proteins, confirming the well-conserved nature of these systems. Most functional groups
contain highly disordered proteins, supporting the general importance of structural disorder in these routes, although some
of them seem to heavily rely on disorder, while others do not. Interestingly, the clathrin system is significantly more
disordered (,23%) than the other two, COPI (,9%) and COPII (,8%). We show that this structural phenomenon enhances
the inherent plasticity and increased evolutionary adaptability of the clathrin system, which distinguishes it from the other
two routes. Since multi-functionality (moonlighting) is indicative of both plasticity and adaptability, we studied its
prevalence in vesicle trafficking proteins and correlated it with structural disorder. Clathrin adaptors have the highest
capability for moonlighting while also comprising the most highly disordered members. The ability to acquire tissue specific
functions was also used to approach adaptability: clathrin route genes have the most tissue specific exons encoding for
protein segments enriched in structural disorder and interaction sites. Overall, our results confirm the general importance of
structural disorder in vesicle trafficking and suggest major roles for this structural property in shaping the differences of
evolutionary adaptability in the three routes
DOC2B: A Novel Syntaxin-4 Binding Protein Mediating Insulin-Regulated GLUT4 Vesicle Fusion in Adipocytes
OBJECTIVE— Insulin stimulates glucose uptake in skeletal muscle and adipose tissues primarily by stimulating the translocation of vesicles containing a facilitative glucose transporter, GLUT4, from intracellular compartments to the plasma membrane. The formation of stable soluble N-ethyl-maleimide–sensitive fusion protein [NSF] attachment protein receptor (SNARE) complexes between vesicle-associated membrane protein-2 (VAMP-2) and syntaxin-4 initiates GLUT4 vesicle docking and fusion processes. Additional factors such as munc18c and tomosyn were reported to be negative regulators of the SNARE complex assembly involved in GLUT4 vesicle fusion. However, despite numerous investigations, the positive regulators have not been adequately clarified
Global analysis of contact-dependent human-to-mouse intercellular mRNA and lncRNA transfer in cell culture
Full-length mRNAs transfer between adjacent mammalian cells via direct cell-to-cell connections called tunneling nanotubes (TNTs). However, the extent of mRNA transfer at the transcriptome-wide level (the 'transferome') is unknown. Here, we analyzed the transferome in an human-mouse cell co-culture model using RNA-sequencing. We found that mRNA transfer is non-selective, prevalent across the human transcriptome, and that the amount of transfer to mouse embryonic fibroblasts (MEFs) strongly correlates with the endogenous level of gene expression in donor human breast cancer cells. Typically, <1% of endogenous mRNAs undergo transfer. Non-selective, expression-dependent RNA transfer was further validated using synthetic reporters. RNA transfer appears contact-dependent via TNTs, as exemplified for several mRNAs. Notably, significant differential changes in the native MEF transcriptome were observed in response to co-culture, including the upregulation of multiple cancer and cancer-associated fibroblast-related genes and pathways. Together, these results lead us to suggest that TNT-mediated RNA transfer could be a phenomenon of physiological importance under both normal and pathogenic conditions
Hearing shapes of drums - mathematical and physical aspects of isospectrality
In a celebrated paper '"Can one hear the shape of a drum?"' M. Kac [Amer.
Math. Monthly 73, 1 (1966)] asked his famous question about the existence of
nonisometric billiards having the same spectrum of the Laplacian. This question
was eventually answered positively in 1992 by the construction of noncongruent
planar isospectral pairs. This review highlights mathematical and physical
aspects of isospectrality.Comment: 42 pages, 60 figure
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