833 research outputs found
Modelling the deceleration of COVID-19 spreading
No full textBy characterizing the time evolution of COVID-19 in term of its 'velocity' (log of the new cases per day) and its rate of variation, or 'acceleration', we show that in many countries there has been a deceleration even before lockdowns were issued. This feature, possibly due to the increase of social awareness, can be rationalized by a susceptible-hidden-infected-recovered model introduced by Barnes, in which a hidden (isolated from the virus) compartment H is gradually populated by susceptible people, thus reducing the effectiveness of the virus spreading. By introducing a partial hiding mechanism, for instance due to the impossibility for a fraction of the population to enter the hidden state, we obtain a model that, although still sufficiently simple, faithfully reproduces the different deceleration trends observed in several major countries
Co-existence of distinct supramolecular assemblies in solution and in the solid state
No full textThe formation of distinct supramolecular assemblies, including a metastable species, is revealed for a lipophilic guanosine (G) derivative in solution and in the solid state. Structurally different G-quartet based assemblies are formed in chloroform depending on the nature of the cation, anion and salt concentration, as characterized by circular dichroism and time course diffusion-ordered NMR spectroscopy data. Intriguingly, even the presence of potassium ions that stabilize G-quartets in chloroform was insufficient to exclusively retain such assemblies in the solid state, leading to the formation of mixed quartet and ribbon-like assemblies as revealed by fast magic-angle spinning (MAS) NMR spectroscopy. Distinct N-H∙∙∙N and N-H∙∙∙O intermolecular hydrogen bonding interactions drive quartet and ribbon-like self-assembly resulting in markedly different 2D 1H solid-state NMR spectra, thus facilitating a direct identification of mixed assemblies. A dissolution NMR experiment confirmed that the quartet and ribbon interconversion is reversible - further demonstrating the changes that occur in the self-assembly process of a lipophilic nucleoside upon a solid-state to solution-state transition and vice versa. A systematic study for complexation with different cations (K+, Sr2+) and anions (picrate, ethanoate and iodide) emphasises that the existence of a stable solution or solid-state structure may not reflect the stability of the same supramolecular entity in another phase
Toward universal models for collective interactions in biomolecular condensates
No full textA wide range of higher-order structures, including dense, liquid-like assemblies, serve as key components of cellular matter. The molecular language of how protein sequences encode the formation and biophysical properties of biomolecular condensates, however, is not completely understood. Recent notion on the scale invariance of the cluster sizes below the critical concentration for phase separation suggests a universal mechanism, which can operate from oligomers to non-stoichiometric assemblies. Here, we propose a model for collective interactions in condensates, based on context-dependent variable interactions. We provide the mathematical formalism, which is capable of describing growing dynamic clusters as well as changes in their material properties. Furthermore, we discuss the consequences of the model to maximize sensitivity to the environmental signals and to increase correlation lengths
Mass attenuation coefficient and its photon interaction derivables of some skeletal muscle relaxants
No full textContext: The study of photon interactions with biological materials is essential in radiation medicine and biology, nuclear technology and space research, since radioactive sources are used.
Aims: A study of mass attenuation coefficient, effective atomic numbers (Zeff) and electron density of some commonly used skeletal muscle relaxants.
Materials and Methods: We have measured the mass attenuation some commonly used skeletal muscle relaxants such as tubocurarine chloride, gallamine triethiodide, pancuronium bromide, suxamethonium bromide and mephenesin for various gamma sources of energy ranging from 84keV to 1330 keV (170Tm, 57Co, 141Ce, 203Hg, 51Cr, 113Sn, 22Na, 137Cs, 60Co, 22Na and 60Co). The measured values agree with the theoretical values. The effective atomic numbers (Zeff) and electron density (Ne) of commonly used skeletal muscle relaxants for total and coherent, incoherent, photoelectric absorption, pair production in atomic and nuclear field photon interaction have been computed in the wide region 1keV to 100GeV using an accurate database of photon-interaction cross sections and the WinXCom program.
Results: The significant variation of Zeff and Nel is due to the variations in the dominance of different interaction process in different energy regions. A comparison is also made with the single values of the Zeff and Nel provided by the program XMuDat. We have also calculated CT numbers, kerma values relative to air and dose rate for relaxants which are also not remaining constant with energy.
Conclusions: The computed data of mass attenuation coefficient, effective atomic numbers (Zeff) and electron density and CT numbers in the low energy region helps in visualizing the image of the biological samples and precise accuracy in treating the inhomogenity of them in medical radiology. The calculated kerma values relative to air and dose rate for relaxants are useful in radiation medicine
A study of photon interaction parameters in lung tissue substitutes
No full textThe study of photon interaction with different composite materials has become a topic of prime importance for radiation physicists. Some parameters of dosimetric interest are the mass attenuation coefficient, effective atomic number, and electron density; these help in the basic understanding of photon interactions with composite materials. The photon interaction parameters such as mass attenuation coefficient (μ/ρ), effective atomic number (Z eff ), and effective electron density (N el ) must be identical for the phantom material and their tissue. In the present study, we have evaluated the photon interaction parameters such as (μ/ρ), Z eff and N el of 13 lung tissue substitutes. The variations of these parameters of lung tissue substitutes with photon energy are graphically represented. The photon interaction parameters of lung tissue substitutes are compared with that of lung tissue. The variation of photon interaction parameters of the studied lung tissue substitutes is similar that of the lung. Logically, it can be shown that Alderson lung is good substitute for lung than the other substitutes
Inhibition of ERK and proliferation in NK cell lines by soluble HLA-E released from Japanese encephalitis virus infected cells
No full textProductive infection of human endothelial cells with Japanese encephalitis virus (JEV), a single stranded RNA virus induces shedding of sHLA-E. We show here that sHLA-E that is released upon infection with this flavivirus can inhibit IL-2 and PMA mediated ERK 1/2 phosphorylation in two NK cell lines, Nishi and NKL. Virus infected or IFN-gamma treated cell culture supernatants containing sHLA-E were found to partially inhibit IL-2 mediated induction of CD25 molecules on NKL cells. It was also found that sHLA-E could inhibit IL-2 induced H-3]-thymidine incorporation suggesting that, similar to cell surface expressed HLA-E, sHLA-E could also inhibit NK cell responses. Hence JEV-induced shedding of sHLA-E needs further investigation to better understand immune responses in JEV infections since it may have a role in viral evasion of NK cell responses. (C) 2014 Elsevier B.V. All rights reserved
Pyrrolo[3,4-c]pyridine-1,3(2H)-diones: A new anti-mycobacterial class that targets mycobacterial energy metabolism
No full textPhenotypic whole-cell high throughput screening of a library of small polar molecules led to the identification of a phthalimide-containing ester hit compound (1), which was optimized for metabolic stability by replacing the ester moiety with a methyl oxadiazole bioisostere. A route utilizing polymer-supported reagents was designed and executed to explore structure activity relationships with respect to the N-benzyl substituent, leading to compounds with nanomolar activity against Mycobacterium tuberculosis. The frontrunner compound (5h) from these studies was well tolerated in mice. A M. tuberculosis cytochrome bd oxidase deletion mutant (∆cydKO) was hyper-susceptible to compounds from this series, and a strain carrying a single point mutation in qcrB, the gene encoding a subunit of the menaquinol cytochrome c oxidoreductase (bc1 complex), was resistant to compounds in this series. In combination, these observations indicate that this novel class of anti-mycobacterial compounds inhibits the cytochrome bc1 complex, a validated drug target in M. tuberculosis.
Author list: Renier van der Westhuyzen, Susan Winks, Colin R. Wilson, Grant A. Boyle, Richard K. Gessner, Candice Soares de Melo, Dale Taylor, Carmen de Kock, Mathew Njoroge, Christel Brunschwig, Nina Lawrence, Frik Sirgel, Paul van Helden, Ronnett Seldon, Atica Moosa, Digby Warner, Luca Arista, Srinivasa Rao, Ujjini H. Manjunatha, Paul W. Smith, Leslie J. Street, Kelly Chibal
Effect of blending and nanoparticles on the ionic conductivity of solid polymer electrolyte systems
No full textThe neuropsychiatric aspects of influenza/swine flu: A selective review
No full textThe world witnessed the influenza virus during the seasonal epidemics and pandemics. The current strain of H1N1 (swine flu) pandemic is believed to be the legacy of the influenza pandemic (1918-19). The influenza virus has been implicated in many neuropsychiatric disorders. In view of the recent pandemic, it would be interesting to review the neuropsychiatric aspects of influenza, specifically swine flu. Author used popular search engine ′PUBMED′ to search for published articles with different MeSH terms using Boolean operator (AND). Among these, a selective review of the published literature was done. Acute manifestations of swine flu varied from behavioral changes, fear of misdiagnosis during outbreak, neurological features like seizures, encephalopathy, encephalitis, transverse myelitis, aseptic meningitis, multiple sclerosis, and Guillian-Barre Syndrome. Among the chronic manifestations, schizophrenia, Parkinson′s disease, mood disorder, dementia, and mental retardation have been hypothesized. Further research is required to understand the etiological hypothesis of the chronic manifestations of influenza. The author urges neuroscientists around the world to make use of the current swine flu pandemic as an opportunity for further research
Investigation on surface roughness and MRR in WEDM of titanium grade 7 (Ti-0.15Pd) alloy using statistical techniques / H. R. Basavaraju, S. S. Manjunatha and R. Suresh
No full textWire Electric Discharge Machining (WEDM) of Titanium grade alloys with coated electrodes has several advantages over the traditional machining process such as increased productivity, reduction of processing cost, and improved material properties. The main objective is to create a relationship between WEDM parameters such as Pulse-on (TON), Pulse-off (TOFF), and Indicated Power (IP) with surface roughness (Ra) and Material Removal Rate (MRR). In the present work, the performance of zinc-coated brass electrodes for WEDM of Titanium Grade-7 alloy was assessed and optimized with statistical technique. ANOVA analysis is used to analysis of the MRR and Ra and validated with regression. The ANOVA analysis results indicated that TON is the highest statistically significant and followed by TOFF and IP on MRR and surface roughness. The optimum combination of higher IP(6 A) and TON time(60 µs) and lower TOFF time (12 µs) is lucrative for a higher MRR of 8.5682 mm3/min and lower surface roughness of 1.66 µm. The SEM images showed homogeneous solidification, columnar grain structure, recast layer surface, and minor surface crack density were noticed at higher cutting conditions. The predicted model and confirmation test results were close to each other with minimum error
- …
