395 research outputs found
A sufficient condition for confinement in QCD
This letter is about confinement in QCD. At the moment we have pictures of
confinement to complete our understanding of the physics of strongly
interacting particles, interaction which asks for confinement.As it is said in
[1] : " In principle it should be possible to derive the confinement hypothesis
from the QCD Lagrangian. At this time, no rigorous derivation exists, so it is
not absolutely clear that the confinement hypothesis is a bone fide prediction
of QCD" . In this letter we show that a sufficient (of course not necessary)
condition for confinement is that topological structure of vacuum in Nature
does not correspond to the -vacuum. Therefore, if different vacua with
nontrivial winding number cannot be connected by tunneling, we obtain
confinement as a consequence.Comment: 10 page
Effective nonlinear Ehrenfest hybrid quantum-classical dynamics
The definition of a consistent evolution equation for statistical hybrid
quantum-classical systems is still an open problem. In this paper we analyze
the case of Ehrenfest dynamics on systems defined by a probability density and
identify the relations of the non-linearity of the dynamics with the
obstructions to define a consistent dynamics for the first quantum moment of
the distribution. This first quantum moment represents the physical states as a
family of classically-parametrized density matrices , for
a classical point; and it is the most common representation of hybrid systems
in the literature. Due to this obstruction, we consider higher order quantum
moments, and argue that only a finite number of them are physically measurable.
Because of this, we propose an effective solution for the hybrid dynamics
problem based on approximating the distribution by those moments and
representing the states by them.Comment: 21 pages. Minor correction in the list of affiliation
GPUs, a new tool of acceleration in CFD: efficiency and reliability on smoothed particle hydrodynamics methods
Smoothed Particle Hydrodynamics (SPH) is a numerical method commonly used in Computational Fluid Dynamics (CFD) to simulate complex free-surface flows. Simulations with this mesh-free particle method far exceed the capacity of a single processor. In this paper, as part of a dual-functioning code for either central processing units (CPUs) or Graphics Processor Units (GPUs), a parallelisation using GPUs is presented. The GPU parallelisation technique uses the Compute Unified Device Architecture (CUDA) of nVidia devices. Simulations with more than one million particles on a single GPU card exhibit speedups of up to two orders of magnitude over using a single-core CPU. It is demonstrated that the code achieves different speedups with different CUDA-enabled GPUs. The numerical behaviour of the SPH code is validated with a standard benchmark test case of dam break flow impacting on an obstacle where good agreement with the experimental results is observed. Both the achieved speed-ups and the quantitative agreement with experiments suggest that CUDA-based GPU programming can be used in SPH methods with efficiency and reliability
Stereospecific generation of homochiral helices in coordination polymers built from enantiopure binaphthyl-based ligands
The novel enantiopure spacer 2,2′-dimethoxy-1,1′-binaphthyl-3,3′-bis(4-pyridyl-amido) has been designed to prepare helical coordination polymers here investigated by means of experimental and theoretical data
Prognostic stratification of adult primary glioblastoma multiforme patients based on their tumor gene amplification profiles
Several classification systems have been proposed to address genomic heterogeneity of glioblastoma multiforme, but they either showed limited prognostic value and/or are difficult to implement in routine diagnostics. Here we propose a prognostic stratification model for these primary tumors based on tumor gene amplification profiles, that might be easily implemented in routine diagnostics, and potentially improve the patients management. Gene amplification profiles were prospectively evaluated in 80 primary glioblastoma multiforme tumors using single-nucleotide polymorphism arrays and the results obtained validated in publicly available data from 267/347 cases. Gene amplification was detected in 45% of patients, and chromosome 7p11.2 including the EGFR gene, was the most frequently amplified chromosomal region – either alone (18%) or in combination with amplification of DNA sequences in other chromosomal regions (10% of cases). Other frequently amplified DNA sequences included regions in chromosomes 12q(10%), 4q12(7%) and 1q32.1(4%). Based on their gene amplification profiles, glioblastomas were subdivided into: i) tumors with no gene amplification (55%); ii) tumors with chromosome 7p/EGFR gene amplification (with or without amplification of other chromosomal regions) (38%); and iii) glioblastoma multiforme with a single (11%) or multiple (6%) amplified DNA sequences in chromosomal regions other than chromosome 7p. From the prognostic point of view, these amplification profiles showed a significant impact on overall survival of glioblastoma multiforme patients (p>0.001). Based on these gene amplification profiles, a risk-stratification scoring system was built for prognostic stratification of glioblastoma which might be easily implemented in routine diagnostics, and potentially contribute to improved patient management.This work was supported by RETICC RD06/0020/0035, RD06/0020/0059 and RD12/0036/0048 grants from Red Temática de Investigación Cooperativa en Cáncer (RTICC), Instituto de Salud Carlos III, Ministerio de Economía y Competitividad, (Madrid, Spain and FONDOS FEDER), AES PI16/000476 (Instituto de Salud Carlos III, Madrid, Spain and FONDOS FEDER), GRS909A14 (JCYL) and CB16/12/00400 grant (CIBERONC, Instituto de Salud Carlos III, Ministerio de Economía y Competitividad, Madrid, Spain and FONDOS FEDER)
Beneficial Effect of Ursodeoxycholic Acid in Patients with ACOX2 Deficiency-Associated Hypertransaminasemia
Background: A variant (p.Arg225Trp) of peroxisomal acyl-CoA oxidase 2 (ACOX2), involved in bile acid (BA) side-chain shortening, has been associated with unexplained persistent hypertransaminasemia and accumulation of C27-BAs, mainly trihydroxycholestanoic acid (THCA).
Aims: To investigate the prevalence of ACOX2 deficiency-associated hypertransaminasemia (ADAH), its response to ursodeoxycholic acid (UDCA), elucidate its pathophysiological mechanism and identify other inborn errors that could cause this alteration.
Methods & results: Among 33 patients with unexplained hypertransaminasemia from 11 hospitals, and 13 of their relatives, 7 individuals with abnormally high C27-BA levels (>50% of total BAs) were identified by HPLC-MS/MS. The p.Arg225Trp variant was found in homozygosity (exon amplification/sequencing) in 2 patients and 3 family members. Two additional non-related patients were heterozygous carriers of different alleles: c.673C>T (p.Arg225Trp) and c.456_459del (p.Thr154fs). In ADAH patients, impaired liver expression of ACOX2, but not ACOX3, was found (immunohistochemistry). Treatment with UDCA normalized transaminases levels. Incubation of HuH-7 liver cells with THCA, which was efficiently taken up, but not through BA transporters, increased ROS production (flow cytometry), ER stress biomarkers (GRP78, CHOP and XBP1-S/XBP1-U ratio), and BAX¿ expression (RT-qPCR and immunoblot), whereas cell viability was decreased (MTT). THCA-induced cell toxicity was higher than that of major C24-BAs and was not prevented by UDCA. Fourteen predicted ACOX2 variants were generated (site-directed mutagenesis) and expressed in HuH-7 cells. Functional tests to determine their ability to metabolize THCA identified six with the potential to cause ADAH.
Conclusion: Dysfunctional ACOX2 has been found in several patients with unexplained hypertransaminasemia. This condition can be accurately identified by a non-invasive diagnostic strategy based on plasma BA profiling and ACOX2 sequencing. Moreover, UDCA treatment can efficiently attenuate liver damage in these patients.This study was supported by the following
grants: CIBERehd (EHD15PI05/2016);
Fondo de Investigaciones Sanitarias,
Instituto de Salud Carlos III, Spain
(PI19/00819 and PI20/00189), co-funded
by European Regional Development
Fund/European Social Fund, “Investing
in your future”; “Junta de Castilla y León”
(SA074P20); Fundació Marato TV3
(201916–31);
AECC Scientific Foundation
(2017/2020), Spain; and “Centro
Internacional sobre el Envejecimiento”
(OLD-HEPAMARKER,
0348_CIE_6_E),
Spain. We also acknowledge support
from grants PID2019-111669RBI-
100,
PID2020-115055RB-
I00
from Plan
Nacional de I+D funded by the “Agencia
Estatal de Investigación” (AEI) and the
center grant P50AA011999 Southern
California Research Center for ALPD
and Cirrhosis funded by NIAAA/NIH,
as well as support from AGAUR of
the “Generalitat de Catalunya” SGR-2017-
1112,
European Cooperation in
Science & Technology (COST) ACTION
CA17112 Prospective European Drug-Induced
Liver Injury Network. Marta
Alonso-Peña
was the recipient of a
predoctoral fellowship from “Ministerio de
Educación, Cultura y Deporte” (BOE-A-
2015-
9456;
FPU-14/
00214) and a Mobility
Grant for Short Stays from “Ministerio
de Ciencia, Innovación y Universidades”
(EST17/00186). Ricardo Espinosa-Escudero
is the recipient of a predoctoral
fellowship from “Junta de Castilla y
León” and “Fondo Social Europeo”
(EDU/574/2018). The funding sources
were not involved in the research design
or preparation of the articl
Nanoinformatics: developing new computing applications for nanomedicine
Nanoinformatics has recently emerged to address the need of computing applications at the nano level. In this regard, the authors have participated in various initiatives to identify its concepts, foundations and challenges. While nanomaterials open up the possibility for developing new devices in many industrial and scientific areas, they also offer breakthrough perspectives for the prevention, diagnosis and treatment of diseases. In this paper, we analyze the different aspects of nanoinformatics and suggest five research topics to help catalyze new research and development in the area, particularly focused on nanomedicine. We also encompass the use of informatics to further the biological and clinical applications of basic research in nanoscience and nanotechnology, and the related concept of an extended ?nanotype? to coalesce information related to nanoparticles. We suggest how nanoinformatics could accelerate developments in nanomedicine, similarly to what happened with the Human Genome and other -omics projects, on issues like exchanging modeling and simulation methods and tools, linking toxicity information to clinical and personal databases or developing new approaches for scientific ontologies, among many others
Physical structure of the envelopes of intermediate-mass protostars
Context: Intermediate mass protostars provide a bridge between low- and
high-mass protostars. Furthermore, they are an important component of the UV
interstellar radiation field. Despite their relevance, little is known about
their formation process. Aims: We present a systematic study of the physical
structure of five intermediate mass, candidate Class 0 protostars. Our two
goals are to shed light on the first phase of intermediate mass star formation
and to compare these protostars with low- and high-mass sources. Methods: We
derived the dust and gas temperature and density profiles of the sample. We
analysed all existing continuum data on each source and modelled the resulting
SED with the 1D radiative transfer code DUSTY. The gas temperature was then
predicted by means of a modified version of the code CHT96. Results: We found
that the density profiles of five out of six studied intermediate mass
envelopes are consistent with the predictions of the "inside-out" collapse
theory.We compared several physical parameters, like the power law index of the
density profile, the size, the mass, the average density, the density at 1000
AU and the density at 10 K of the envelopes of low-, intermediate, and
high-mass protostars. When considering these various physical parameters, the
transition between the three groups appears smooth, suggesting that the
formation processes and triggers do not substantially differ
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