4,397 research outputs found
Connecticut's Spending Cap: It's History and An Alternative Spending Growth Rule
State spending growth rules and an alternative for Connecticutstate tax policy, spending growth rules, tax and expenditure limits, TELs
A quantum mechanical analysis of the light-harvesting complex 2 from purple photosynthetic bacteria. Insights into the electrostatic effects of transmembrane helices
We perform a quantum mechanical study of the peptides that are part of the
LH2 complex from Rhodopseudomonas acidophila, a non-sulfur purple bacteria that
has the ability of producing chemical energy from photosynthesis. The
electronic structure calculations indicate that the transmembrane helices of
these peptides are characterized by dipole moments with a magnitude of ~150 D.
When the full nonamer assembly made of eighteen peptides is considered, then a
macrodipole of magnitude 704 D is built up from the vector sum of each monomer
dipole. The macrodipole is oriented normal to the membrane plane and with the
positive tip toward the cytoplasm thereby indicating that the electronic charge
of the protein scaffold is polarized toward the periplasm. The results obtained
here suggest that the asymmetric charge distribution of the protein scaffold
contributes an anisotropic electrostatic environment which differentiates the
absorption properties of the bacteriochlorophyll pigments, B800 and B850,
embedded in the LH2 complex.Comment: 14 pages, 7 figure
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
A Bifactor Model of the Polish Version of the Hare Self-Report Psychopathy Scale
The 64-item Hare Self-Report Psychopathy Scale was translated into Polish with the aim to test construct validity and dimensionality, incremental validity, and composite reliability of the measure in a sample of working adults (N = 319). Confirmatory factor analyses revealed that the best fitting model was the bifactor conceptualization containing six latent factors; two general factors of psychopathy and four grouping factors represented by interpersonal, affective, antisocial, and lifestyle latent variables (compared to a 2-factor, 4-factor, and 4-factor with 2 hierarchical factors). The scores of the Polish version of Hare SRP evidenced good composite reliability and incremental validity in terms of predicting scores on aggression scale. Implications for theory and future research are discussed
Evidence for surface defect passivation as the origin of the remarkable photostability of unencapsulated perovskite solar cells employing aminovaleric acid as a processing additive
This study addresses the cause of enhanced stability of methyl ammonium lead iodide when processed with aminovaleric acid additives (AVA-MAPbI3) in screen printed, hole transport layer free perovskite solar cells with carbon top electrodes (c-PSC). Employing AVA as an additive in the active layer caused a 40-fold increase in device lifetime measured under full sun illumination in ambient air (RH ∼ 15%). This stability improvement with AVA was also observed in optical photobleaching studies of planar films on glass, indicating this improvement is intrinsic to the perovskite film. Employing low-energy ion scattering spectroscopy, photoluminescence studies as a function of AVA and oxygen exposure, and a molecular probe for superoxide generation, we conclude that even though superoxide is generated in both AVA-MAPbI3 and MAPbI3 films, AVA located at grain boundaries is able to passivate surface defect sites, resulting in enhanced resistivity to oxygen induced degradation. These results are discussed in terms of their implications for the design of environmentally stable perovskite solar cells
Weakly acidic, but strongly irritating: TRPA1 and the activation of nociceptors by cytoplasmic acidification
On manifolds with nonhomogeneous factors
We present simple examples of finite-dimensional connected homogeneous spaces
(they are actually topological manifolds) with nonhomogeneous and nonrigid
factors. In particular, we give an elementary solution of an old problem in
general topology concerning homogeneous spaces
Trigeminal injury causes kappa opioid-dependent allodynic, glial and immune cell responses in mice
Abstract Background The dynorphin-kappa opioid receptor (KOR) system regulates glial proliferation after sciatic nerve injury. Here, we investigated its role in cell proliferation following partial ligation of infraorbital nerve (pIONL), a model for trigeminal neuropathic pain. Mechanical allodynia was enhanced in KOR gene deleted mice (KOR-/-) compared to wild type mice. Using bromodeoxyuridine (BrdU) as a mitotic marker, we assessed cell proliferation in three different areas of the trigeminal afferent pathway: trigeminal nucleus principalis (Vp), trigeminal root entry zone (TREZ), and trigeminal ganglion (TG). Results In KOR-/- mice or norBNI-treated mice, the number of proliferating cells in the Vp was significantly less than in WT mice, whereas cell proliferation was enhanced in TREZ and TG. The majority of the proliferating cells were nestin positive stem cells or CD11b positive microglia in the Vp and macrophages in the TG. GFAP-positive astrocytes made a clear borderline between the CNS and the PNS in TREZ, and phosphorylated KOR staining (KOR-p) was detectable only in the astrocytes in CNS in WT mice but not in KOR-/- or norBNI-treated mice. Conclusions These results show that kappa opioid receptor system has different effects after pIONL in CNS and PNS: KOR activation promotes CNS astrocytosis and microglial or stem cell proliferation but inhibits macrophage proliferation in PNS. The trigeminal central root has a key role in the etiology and treatment of trigeminal neuralgia, and these newly identified responses may provide new targets for developing pain therapies
Quantum phases in artificial molecules
The many-body state of carriers confined in a quantum dot is controlled by
the balance between their kinetic energy and their Coulomb correlation. In
coupled quantum dots, both can be tuned by varying the inter-dot tunneling and
interactions. Using a theoretical approach based on the diagonalization of the
exact Hamiltonian, we show that transitions between different quantum phases
can be induced through inter-dot coupling both for a system of few electrons
(or holes) and for aggregates of electrons and holes. We discuss their
manifestations in addition energy spectra (accessible through capacitance or
transport experiments) and optical spectra.Comment: 29 pages, 8 figures (ps and eps), LaTeX 2e, ELSART package. To appear
in Solid State Communications - Special Issue on Spin Effects in Mesoscopic
System
The K-theoretic Farrell-Jones Conjecture for hyperbolic groups
We prove the K-theoretic Farrell-Jones Conjecture for hyperbolic groups with
(twisted) coefficients in any associative ring with unit.Comment: 33 pages; final version; to appear in Invent. Mat
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