12,099 research outputs found
Evolutionarily Conserved Sequence Features Regulate the Formation of the FG Network at the Center of the Nuclear Pore Complex.
The nuclear pore complex (NPC) is the portal for bidirectional transportation of cargos between the nucleus and the cytoplasm. While most of the structural elements of the NPC, i.e. nucleoporins (Nups), are well characterized, the exact transport mechanism is still under much debate. Many of the functional Nups are rich in phenylalanine-glycine (FG) repeats and are believed to play the key role in nucleocytoplasmic transport. We present a bioinformatics study conducted on more than a thousand FG Nups across 252 species. Our results reveal the regulatory role of polar residues and specific sequences of charged residues, named 'like charge regions' (LCRs), in the formation of the FG network at the center of the NPC. Positively charged LCRs prepare the environment for negatively charged cargo complexes and regulate the size of the FG network. The low number density of charged residues in these regions prevents FG domains from forming a relaxed coil structure. Our results highlight the significant role of polar interactions in FG network formation at the center of the NPC and demonstrate that the specific localization of LCRs, FG motifs, charged, and polar residues regulate the formation of the FG network at the center of the NPC
Dataset concerning the analytical approximation of the Ae3 temperature.
In this paper we present a new polynomial function for calculating the local phase transformation temperature (Ae3 ) between the austenite+ferrite and the fully austenitic phase fields during heating and cooling of steel:[Formula: see text] The dataset includes the terms of the function and the values for the polynomial coefficients for major alloying elements in steel. A short description of the approximation method used to derive and validate the coefficients has also been included. For discussion and application of this model, please refer to the full length article entitled "The role of aluminium in chemical and phase segregation in a TRIP-assisted dual phase steel" 10.1016/j.actamat.2016.05.046 (Ennis et al., 2016) [1]
Recently published papers: Acute kidney injury â diagnosis and treatment
When faced with the management of the patient on intensive care with acute kidney injury, the clinician has various choices to consider. The conventional therapy, where appropriate, is renal replacement therapy. This technique used to be relatively straightforward but now a relative feast of alternatives is available, not least in choice of buffer and anticoagulant. Two recent studies add to the growing body of literature concerning alternative anticoagulant regimes, and one in particular should lead to a change in practice for many of us. We also review some new studies on biomarkers in the diagnosis of acute kidney injury as well as add yet another nail in the coffin for loop diuretics in the therapy of acute kidney injury
Structure and optical properties of Lu <inf>2</inf>SiO <inf>5</inf>:Ce phosphor thin films
Luminescent, cerium doped Lu 2SiO 5 thin films with C2/c symmetry have been prepared by pulsed laser deposition (PLD) at temperatures much lower than the crystallization temperature (2150°C) of the corresponding bulk crystals. The PLD grown films show the typical luminescence resulting from the Ce 3+ 5d-4f transition. Maximum luminescence efficiency was observed for films prepared at an oxygen partial pressure of 200 mTorr at 600°C. These conditions reflect a balance between Ce 4+/Ce 3+ interconversion and the crystalline quality of the films. The results indicate that PLD offers a low temperature deposition technique for complex oxide phosphor materials. © 2006 American Institute of Physics
Successful tactile based visual sensory substitution use functions independently of visual pathway integrity
Purpose: Neuronal reorganization after blindness is of critical interest because it has implications for the rational prescription of artificial vision devices. The purpose of this study was to distinguish the microstructural differences between perinatally blind (PB), acquired blind (AB), and normally sighted controls (SCs) and relate these differences to performance on functional tasks using a sensory substitution device (BrainPort). Methods: We enrolled 52 subjects (PB n = 11; AB n = 35; SC n = 6). All subjects spent 15 h undergoing BrainPort device training. Outcomes of light perception, motion, direction, temporal resolution, grating, and acuity were tested at baseline and after training. Twenty-six of the subjects were scanned with a three Tesla MRI scanner for diffusion tensor imaging (DTI), and with a positron emission tomography (PET) scanner for mapping regional brain glucose consumption during sensory substitution function. Non-parametric models were used to analyze fractional anisotropy (FA; a DTI measure of microstructural integrity) of the brain via region-of-interest (ROI) analysis and tract-based spatial statistics (TBSS). Results: At baseline, all subjects performed all tasks at chance level. After training, light perception, time resolution, location and grating acuity tasks improved significantly for all subject groups. ROI and TBSS analyses of FA maps show areas of statistically significant differences (p †0.025) in the bilateral optic radiations and some visual association connections between all three groups. No relationship was found between FA and functional performance with the BrainPort. Discussion: All subjects showed performance improvements using the BrainPort irrespective of nature and duration of blindness. Definite brain areas with significant microstructural integrity changes exist among PB, AB, and NC, and these variations are most pronounced in the visual pathways. However, the use of sensory substitution devices is feasible irrespective of microstructural integrity of the primary visual pathways between the eye and the brain. Therefore, tongue based devices devices may be usable for a broad array of non-sighted patients. © 2014 Lee, Nau, Laymon, Chan, Rosario and Fisher
Random Matrix Theory and Chiral Symmetry in QCD
Random matrix theory is a powerful way to describe universal correlations of
eigenvalues of complex systems. It also may serve as a schematic model for
disorder in quantum systems. In this review, we discuss both types of
applications of chiral random matrix theory to the QCD partition function. We
show that constraints imposed by chiral symmetry and its spontaneous breaking
determine the structure of low-energy effective partition functions for the
Dirac spectrum. We thus derive exact results for the low-lying eigenvalues of
the QCD Dirac operator. We argue that the statistical properties of these
eigenvalues are universal and can be described by a random matrix theory with
the global symmetries of the QCD partition function. The total number of such
eigenvalues increases with the square root of the Euclidean four-volume. The
spectral density for larger eigenvalues (but still well below a typical
hadronic mass scale) also follows from the same low-energy effective partition
function. The validity of the random matrix approach has been confirmed by many
lattice QCD simulations in a wide parameter range. Stimulated by the success of
the chiral random matrix theory in the description of universal properties of
the Dirac eigenvalues, the random matrix model is extended to nonzero
temperature and chemical potential. In this way we obtain qualitative results
for the QCD phase diagram and the spectrum of the QCD Dirac operator. We
discuss the nature of the quenched approximation and analyze quenched Dirac
spectra at nonzero baryon density in terms of an effective partition function.
Relations with other fields are also discussed.Comment: invited review article for Ann. Rev. Nucl. Part. Sci., 61 pages, 11
figures, uses ar.sty (included); references added and typos correcte
Sequestration of Martian CO2 by mineral carbonation
Carbonation is the water-mediated replacement of silicate minerals, such as olivine, by carbonate, and is commonplace in the Earthâs crust. This reaction can remove significant quantities of CO2 from the atmosphere and store it over geological timescales. Here we present the first direct evidence for CO2 sequestration and storage on Mars by mineral carbonation. Electron beam imaging and analysis show that olivine and a plagioclase feldspar-rich mesostasis in the Lafayette meteorite have been replaced by carbonate. The susceptibility of olivine to replacement was enhanced by the presence of smectite veins along which CO2-rich fluids gained access to grain interiors. Lafayette was partially carbonated during the Amazonian, when liquid water was available intermittently and atmospheric CO2 concentrations were close to their present-day values. Earlier in Marsâ history, when the planet had a much thicker atmosphere and an active hydrosphere, carbonation is likely to have been an effective mechanism for sequestration of CO2
Algebraic charge liquids
High temperature superconductivity emerges in the cuprate compounds upon
changing the electron density of an insulator in which the electron spins are
antiferromagnetically ordered. A key characteristic of the superconductor is
that electrons can be extracted from them at zero energy only if their momenta
take one of four specific values (the `nodal points'). A central enigma has
been the evolution of the zero energy electrons in the metallic state between
the antiferromagnet and the superconductor, and recent experiments yield
apparently contradictory results. The oscillation of the resistance in this
metal as a function of magnetic field indicate that the zero energy electrons
carry momenta which lie on elliptical `Fermi pockets', while ejection of
electrons by high intensity light indicates that the zero energy electrons have
momenta only along arc-like regions. We present a theory of new states of
matter, which we call `algebraic charge liquids', which arise naturally between
the antiferromagnet and the superconductor, and reconcile these observations.
Our theory also explains a puzzling dependence of the density of
superconducting electrons on the total electron density, and makes a number of
unique predictions for future experiments.Comment: 6+8 pages, 2 figures; (v2) Rewritten for broader accessibility; (v3)
corrected numerical error in Eq. (5
Age-related macular degeneration and smoking cessation advice by eye care providers: a pilot study
This is the final version of the article. Available from the publisher via the link in this record.Smoking is a modifiable risk factor for age-related macular degeneration (AMD), the leading cause of irreversible vision loss in the United States. We conducted a pilot study among eye care providers and AMD patients to assess smoking cessation preferences and cessation services offered at a large academic medical center. Most patients who smoke reported never being advised to quit smoking, although most eye care providers reported that they had advised smokers to quit. Two-thirds of providers expressed a desire for additional training and resources to support patient quit attempts, indicating the need for the integration of smoking cessation opportunities in the clinic setting.Support for this study was provided in part by a National Eye Institute grant (no. R21-EY019096)
The relationship between psychological states and health perception in individuals at risk for cardiovascular disease
© 2019 Lee et al. Backgrounds: Perceptions of health are important to motivate people to change behaviors. Non-adherence to healthy behaviors that prevent cardiovascular disease may result from inadequate health perceptions. However, there are few studies investigating relationships between health perceptions and psychological states. Objective: To determine whether psychological states (ie, depressive symptoms and anxi-ety) are associated with the congruency between health perception and estimated risk for cardiovascular disease in adults with 2 or more cardiovascular disease risk factors. Methods: Community dwellers at risk for cardiovascular disease were asked to complete the Patient Health Questionnaire-9 and the anxiety subscale of the Brief Symptom Inventory to measure depressive symptoms and anxiety, respectively. Participants rated their perceived health from excellent to poor. The estimated cardiovascular disease risks were measured with the 10-year cardiovascular disease Framingham risk scores. Participants were grouped into three health perception groups based on congruency between levels of health perception and cardiovascular disease risk. Multivariate multinomial logistic regression was done to examine the association between psychological states and health perception groups. Results: Of 828 participants 54.7%, 12.0%, and 33.3% had congruent, pessimistically biased, and optimistically biased health perception, respectively. Depressive symptoms were significantly associated with pessimistic bias (adjusted odds ratio: 1.070, 95% confidence interval 1.010â1.133), but not anxiety. Optimistic bias was not associated with either depressive symptoms or anxiety. Conclusions: A mismatch between individual health perceptions and cardiovascular disease risks was associated with depressive symptoms. As health perception is affected by depressive symptoms, clinicians should assess depressive symptoms when exploring health perceptions and engaging individuals in decision-making about a healthy lifestyle
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