2,304 research outputs found
Semiclassical theory for small displacements
Characteristic functions contain complete information about all the moments
of a classical distribution and the same holds for the Fourier transform of the
Wigner function: a quantum characteristic function, or the chord function.
However, knowledge of a finite number of moments does not allow for accurate
determination of the chord function. For pure states this provides the overlap
of the state with all its possible rigid translations (or displacements). We
here present a semiclassical approximation of the chord function for large
Bohr-quantized states, which is accurate right up to a caustic, beyond which
the chord function becomes evanescent. It is verified to pick out blind spots,
which are displacements for zero overlaps. These occur even for translations
within a Planck area of the origin. We derive a simple approximation for the
closest blind spots, depending on the Schroedinger covariance matrix, which is
verified for Bohr-quantized states.Comment: 16 pages, 4 figures
Cluster Algorithm Renormalization Group Study of Universal Fluctuations in the 2D Ising Model
In this paper we propose a novel method to study critical systems numerically
by a combined collective-mode algorithm and Renormalization Group on the
lattice. This method is an improved version of MCRG in the sense that it has
all the advantages of cluster algorithms. As an application we considered the
2D Ising model and studied wether scale invariance or universality are possible
underlying mechanisms responsible for the approximate "universal fluctuations"
close to a so-called bulk temperature . "Universal fluctuations" was
first proposed in [1] and stated that the probability density function of a
global quantity for very dissimilar systems, like a confined turbulent flow and
a 2D magnetic system, properly normalized to the first two moments, becomes
similar to the "universal distribution", originally obtained for the
magnetization in the 2D XY model in the low temperature region. The results for
the critical exponents and the renormalization group flow of the probability
density function are very accurate and show no evidence to support that the
approximate common shape of the PDF should be related to both scale invariance
or universal behavior.Comment: 6 pages, 4 figures and 3 table
HUNK Phosphorylates Rubicon to Support Autophagy
Background: Autophagy is a catabolic cellular recycling pathway that is essential for maintaining intracellular homeostasis. Autophagosome formation is achieved via the coordination of the Beclin-1 protein complex. Rubicon is a Beclin-1 associated protein that suppresses autophagy by impairing the activity of the class III PI3K, Vps34. However, very little is known about the molecular mechanisms that regulate Rubicon function. Methods: In this study, co-immunoprecipitation and kinase assays were used to investigate the ability of Hormonally Upregulated Neu-associated Kinase (HUNK) to bind to and phosphorylate Rubicon. LC3B was monitored by immunofluorescence and immunoblotting to determine whether phosphorylation of Rubicon by HUNK controls the autophagy suppressive function of Rubicon. Results: Findings from this study identify Rubicon as a novel substrate of HUNK and show that phosphorylation of Rubicon inhibits its function, promoting autophagy
Serum creatine kinase isoenzymes in children with osteogenesis imperfecta
This study evaluates serum creatine kinase isoenzyme
activity in children with osteogenesis imperfecta to determine
its usefulness as a biochemical marker during treatment
with bisphosphonate. The changes of creatine kinase
(CK) isoenzyme activity during and after discontinuation therapy
were observed. These results could be useful in addressing
over-treatment risk prevention.
Introduction The brain isoenzyme of creatine kinase (CKbb)
is highly expressed in mature osteoclasts during osteoclastogenesis,
thus plays an important role in bone resorption. We
previously identified high serum CKbb levels in 18 children
with osteogenesis imperfect (OI) type 1 treated for 1 year with
bisphosphonate (neridronate). In the present study, serum CK
isoenzymes were evaluated in the same children with continuous
versus discontinued neridronate treatment over a further
2-year follow-up period.
Methods This study included 18 children with OI type 1, 12
with continued (group A) and 6 with ceased (group B)
neridronate treatment. Auxological data, serum biochemical
markers of bone metabolism, bone mineral density z-score,
and serum total CK and isoenzyme activities were determined
in both groups.
Results Serum CKbb was progressively and significantly increased
in group A (p < 0.004) but rapidly decreased to undetectable
levels in group B. In both groups, the cardiac muscle
creatine kinase isoenzyme (CKmb) showed a marked decrease,
while serum C-terminal telopeptide (CTx) levels were
almost unchanged.
Conclusions This study provides evidence of the cumulative
effect of neridronate administration in increasing serum CKbb
levels and the reversible effect after its discontinuation. This
approach could be employed for verifying the usefulness of
serum CKbb as a biochemical marker in patients receiving
prolonged bisphosphonate treatment. Moreover, the decreased
serum CKmb levels suggest a systemic effect of these drugs
The br2 – weighting Method for Estimating the Effects of Air Pollution on Population Health
Uncertainties, limitations and biases may impede the correct application of concentration-response linear functions to estimate the effects of air pollution exposure on population health. The reliability of a prediction depends largely on the strength of the linear correlation between the studied variables. This work proposes the joint use of the coefficient of determination, r2, with the regression slope, b, as an improved measure of the strength of the linear relation between air pollution and its effects on population health. The proposed br2‑weighting method offers more reliable inferences about the potential effects of air pollution on population health, and can be applied universally to other fields of research
Human genetics and genomics research in Ecuador: historical survey, current state, and future directions
Background: In South America, the history of human genetics is extensive and its beginnings go back to the onset of the twentieth century. In Ecuador, the historical record of human genetics and genomics research is limited. In this context, our work analyzes the current status and historical panorama of these fields, based on bibliographic searches in Scopus, Google Scholar, PubMed, and Web of Science.
Results: Our results determined that the oldest paper in human genetics coauthored by an Ecuadorian institution originates from the Central University of Ecuador in 1978. From a historical standpoint, the number of articles has increased since the 1990s. This growth has intensified and it is reflected in 137 manuscripts recorded from 2010 to 2019. Areas such as human population genetics, phylogeography, and forensic sciences are the core of genetics and genomics-associated research in Ecuador. Important advances have been made in the understanding of the bases of cancer, some genetic diseases, and congenital disorders. Fields such as pharmacogenetics and pharmacogenomics have begun to be explored during the last years.
Conclusions: This work paints a comprehensive picture and provides additional insights into the future panorama of human genetic and genomic research in Ecuador as an example of an emerging, resource-limited country with interesting phylogeographic characteristics and public health implications
Microstructural characterisation of Ti-Nb-(Fe-Cr) alloys obtained by powder metallurgy
[EN] beta alloys based on the Ti Nb alloy system are of growing interest to the biomaterial community. The addition of small amounts of Fe and Cr further increases beta-phase stability, improving the properties of Ti Nb alloy. However, PM materials sintered from elemental powders are inhomogeneous due to restricted solid state diffusion and mechanical alloying provides a route to enhance mixing and lemental diffusion. The microstructural characteristics and bend strength of Ti Nb (Fe Cr) alloys obtained from elemental powder mixture and mechanical alloyed powders are compared. Mechanical alloying gives more homogeneous compositions and particle morphology, characterised by rounded, significantly enlarged particles. In the sintered samples alpha and beta phase are observed. The alpha phase appears at the grain boundaries and in lamellae growing inward from the edge, and is depleted in Nb. The b phase is enriched with Nb, Fe and Cr. The addition of Fe and Cr significantly increases the mechanical properties of Ti Nb alloys, providing increased ductility.This paper is based on a presentation at Euro PM 2014, organised by EPMA in Salzburg, Austria on 21-24 September 2014. This work was funded by UPV by the Staff Training Program for Predoctoral Researchers dated 28 February 2014. The Ministry of Science and Innovation of Spain by project research MAT2011-28492-C03 and Generalitat Valenciana by ACOMP / 2014/151.Amigó Mata, A.; Zambrano, JC.; MartÃnez, S.; Amigó Borrás, V. (2014). Microstructural characterisation of Ti-Nb-(Fe-Cr) alloys obtained by powder metallurgy. Powder Metallurgy. 57(5):316-319. https://doi.org/10.1179/0032589914Z.000000000210S316319575Niinomi, M. (1998). Mechanical properties of biomedical titanium alloys. Materials Science and Engineering: A, 243(1-2), 231-236. doi:10.1016/s0921-5093(97)00806-xWen, M., Wen, C., Hodgson, P., & Li, Y. (2014). 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Materials Science and Engineering: A, 418(1-2), 25-35. doi:10.1016/j.msea.2005.10.057Bidaux, J.-E., Closuit, C., Rodriguez-Arbaizar, M., Zufferey, D., & Carreño-Morelli, E. (2013). Metal injection moulding of low modulus Ti–Nb alloys for biomedical applications. Powder Metallurgy, 56(4), 263-266. doi:10.1179/0032589913z.000000000118Zhao, D., Chang, K., Ebel, T., Qian, M., Willumeit, R., Yan, M., & Pyczak, F. (2014). Titanium carbide precipitation in Ti–22Nb alloy fabricated by metal injection moulding. Powder Metallurgy, 57(1), 2-4. doi:10.1179/0032589914z.000000000153Zou, L. M., Yang, C., Long, Y., Xiao, Z. Y., & Li, Y. Y. (2012). Fabrication of biomedical Ti–35Nb–7Zr–5Ta alloys by mechanical alloying and spark plasma sintering. Powder Metallurgy, 55(1), 65-70. doi:10.1179/1743290111y.0000000021Suryanarayana, C. (2001). Mechanical alloying and milling. Progress in Materials Science, 46(1-2), 1-184. doi:10.1016/s0079-6425(99)00010-9EN ISO-3325·2000: ‘Sintered metal materials, excluding hardmetals. Determination of transverse rupture strength’.Afonso, C. R. M., Aleixo, G. T., Ramirez, A. J., & Caram, R. (2007). Influence of cooling rate on microstructure of Ti–Nb alloy for orthopedic implants. Materials Science and Engineering: C, 27(4), 908-913. doi:10.1016/j.msec.2006.11.001Zhao, D., Chang, K., Ebel, T., Qian, M., Willumeit, R., Yan, M., & Pyczak, F. (2013). Microstructure and mechanical behavior of metal injection molded Ti–Nb binary alloys as biomedical material. Journal of the Mechanical Behavior of Biomedical Materials, 28, 171-182. doi:10.1016/j.jmbbm.2013.08.013Angelo PC and Subramanian R: ‘Powder metallurgy: science, technology and applications’, 1–5, 105–109, 132–133; 2009, New Delhi, PHI Learning.Lee, C. M., Ju, C. P., & Chern Lin, J. H. (2002). Structure-property relationship of cast Ti-Nb alloys. 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Clearing extracellular alpha-synuclein from cerebrospinal fluid: A new therapeutic strategy in parkinson’s disease
This concept article aims to show the rationale of targeting extracellular α-Synuclein (α-Syn) from cerebrospinal fluid (CSF) as a new strategy to remove this protein from the brain in Parkinson’s disease (PD). Misfolding and intracellular aggregation of α-synuclein into Lewy bodies are thought to be crucial in the pathogenesis of PD. Recent research has shown that small amounts of monomeric and oligomeric α-synuclein are released from neuronal cells by exocytosis and that this extracellular alpha-synuclein contributes to neurodegeneration, progressive spreading of alpha-synuclein pathology, and neuroinflammation. In PD, extracellular oligomeric-α-synuclein moves in constant equilibrium between the interstitial fluid (ISF) and the CSF. Thus, we expect that continuous depletion of oligomeric-α-synuclein in the CSF will produce a steady clearance of the protein in the ISF, preventing transmission and deposition in the brain
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