626 research outputs found
Multiparticle states in braided lightlike -Minkowski noncommutative QFT
In this study, we construct a 1+1-dimensional, relativistic, free, complex
scalar Quantum Field Theory on the noncommutative spacetime known as lightlike
-Minkowski. The associated -Poincar\'e quantum group of
isometries is triangular, and its quantum R matrix enables the definition of a
braided algebra of N points that retains -Poincar\'e invariance.
Leveraging our recent findings, we can now represent the generators of the
deformed oscillator algebra as nonlinear redefinitions of undeformed
oscillators, which are nonlocal in momentum space. The deformations manifest at
the multiparticle level, as the one-particle states are identical to the
undeformed ones. We successfully introduce a covariant and involutive deformed
flip operator using the R matrix. The corresponding deformed
(anti-)symmetrization operators are covariant and idempotent, allowing for a
well-posed definition of multiparticle states, a result long sought in Quantum
Field Theory on -Minkowski. We find that P and T are not symmetries of
the theory, although PT (and hence CPT) is. We conclude by noticing that
identical particles appear distinguishable in the new theory, and discuss the
fate of the Pauli exclusion principle in this setting.Comment: 29 pages, 2 figure
The fate of Galilean relativity in minimal-length theories
A number of arguments at the interplay of general relativity and quantum
theory suggest an operational limit to spatial resolution, conventionally
modelled as a generalized uncertainty principle (GUP). Recently, it has been
demonstrated that the dynamics postulated as a part of these models are only
loosely related to the existence of the minimal-length scale. In this paper, we
intend to make a more informed choice on the Hamiltonian by demanding, among
other properties, that the model be invariant under (possibly) deformed
Galilean transformations in one dimension. In this vein, we study a
two-particle system with general interaction potential under the condition that
the composition as well as the action of Galilean boosts on wave numbers be
deformed so as to comply with the cut-off. We find that the customary
GUP-Hamiltonian does not allow for invariance under (any kind of) generalised
Galilean transformations. Those Hamiltonians which allow for a deformed
relativity principle have to be related to the ordinary Galilean ones by virtue
of a momentum-space diffeomorphism, i.e. a canonical transformation. Far from
being trivial, the resulting dynamics is deformed, as we show at the example of
the harmonic interaction.Comment: 21 pages, 2 figures, 1 appendi
Olbia greca: il contesto di via Cavour
Le vicende storiche della fase fenicia (metà VIII sec. a.C.-630 circa) e greca (630 circa-fine VI sec.) di Olbia erano state desunte fino al 2006 dai materiali archeologici fuori contesto. Si pubblica qui integralmente l’unico contesto arcaico finora rinvenuto (marzo 2006): il riempimento di una fossa sulla roccia che contiene materiale solo greco databile tra 630 circa e primi VI sec. Esso definitivamente conferma l’esistenza della fase greca di Olbia e la sua attribuzione ad un momento di espansione insediativa di Focea in Occidente più precoce di quanto finora noto, precedente di circa un trentennio la fondazione di Massalia del 600 a.C.  The history of Phoenician (middle VIII cent. B.C.-around 630) and Greek (around 630 B.C.-late VI cent.) Olbia was based, till 2006, on the archaeological finds coming out of context. We entirely publish here the only archaic context founded till now (march 2006): the filling of a grave excavated on the bedrock that contains only Greek pottery dated around 630 and the early VI cent. This excavation definitely proves the existence of a Greek phase in Olbia and its attribution to the expansion of Greek Phokaia to the West Mediterranean in a earlier period than known, 30 years before the foundation of Massalia in 600 B.C.
Metabolomics: moving towards personalized medicine
In many fields of medicine there is a growing interest in characterizing diseases at molecular level with a view to developing an individually tailored therapeutic approach. Metabolomics is a novel area that promises to contribute significantly to the characterization of various disease phenotypes and to the identification of personal metabolic features that can predict response to therapies. Based on analytical platforms such as mass spectrometry or NMR-based spectroscopy, the metabolomic approach enables a comprehensive overview of the metabolites, leading to the characterization of the metabolic fingerprint of a given sample. These metabolic fingerprints can then be used to distinguish between different disease phenotypes and to predict a drug's effectiveness and/or toxicity
Corrigendum to a new neurocognitive interpretation of shoulder position sense during reaching:unexpected competence in the measurement of extracorporeal space
[This corrects the article DOI: 10.1155/2016/9065495.
A new neurocognitive interpretation of shoulder position sense during reaching: unexpected competence in the measurement of extracorporeal space
Background.The position sense of the shoulder joint is important during reaching. Objective. To examine the existence of additional
competence of the shoulder with regard to the ability to measure extracorporeal space, through a novel approach, using the shoulder
proprioceptive rehabilitation tool (SPRT), during reaching. Design. Observational case-control study. Methods. We examined 50
subjects: 25 healthy and 25 with impingement syndrome with a mean age [years] of 64.52 +/− 6.98 and 68.36 +/− 6.54, respectively.
Two parameters were evaluated using the SPRT: the integration of visual information and the proprioceptive afferents of the
shoulder (Test 1) and the discriminative proprioceptive capacity of the shoulder, with the subject blindfolded (Test 2). These tasks
assessed the spatial error (in centimeters) by the shoulder joint in reaching movements on the sagittal plane. Results. The shoulder
had proprioceptive features that allowed it to memorize a reaching position and reproduce it (error of 1.22 cm to 1.55 cm in healthy
subjects). This ability was lower in the impingement group, with a statistically significant difference compared to the healthy group
( < 0.05 by Mann–Whitney test). Conclusions. The shoulder has specific expertise in the measurement of the extracorporeal space
during reaching movements that gradually decreases in impingement syndrome
Quantum Euler angles and agency-dependent spacetime
Quantum gravity is expected to introduce quantum aspects into the description
of reference frames. Here we set the stage for exploring how quantum gravity
induced deformations of classical symmetries could modify the transformation
laws among reference frames in an effective regime. We invoke the quantum group
as a description of deformed spatial rotations and interpret states
of a representation of its algebra as describing the relative orientation
between two reference frames. This leads to a quantization of one of the Euler
angles and to the new paradigm of agency-dependence: space is reconstructed as
a collection of fuzzy points, exclusive to each agent, which depends on their
choice of reference frame. Each agent can choose only one direction in which
points can be sharp, while points in all other directions become fuzzy in a way
that depends on this choice. Two agents making different choices will thus
observe the same points with different degrees of fuzziness.Comment: 9 pages, 3 figures, 4 appendice
The effect of postmastectomy radiation therapy on breast implants. Material analysis on silicone and polyurethane prosthesis
The pathogenic mechanism underlying capsular contracture is still unknown. It is certainly a multifactorial process, resulting from human body reaction, biofilm activation, bacteremic seeding, or silicone exposure. The scope of the present article is to investigate the effect of hypofractionated radiotherapy protocol (2.66 Gy × 16 sessions) both on silicone and polyurethane breast implants.Silicone implants and polyurethane underwent irradiation according to a hypofractionated radiotherapy protocol for the treatment of breast cancer. After irradiation implant shells underwent mechanical, chemical, and microstructural evaluation by means of tensile testing, infrared spectra in attenuated total reflectance mode, nuclear magnetic resonance, and field emission scanning electron microscopy.At superficial analysis, irradiated silicone samples show several visible secondary and tertiary blebs. Polyurethane implants showed an open cell structure, which closely resembles a sponge. Morphological observation of struts from treated polyurethane sample shows a more compact structure, with significantly shorter and thicker struts compared with untreated sample. The infrared spectra in attenuated total reflectance mode spectra of irradiated and control samples were compared either for silicon and polyurethane samples. In the case of silicone-based membranes, treated and control specimens showed similar bands, with little differences in the treated one. Nuclear magnetic resonance spectra on the fraction soluble in CDCl3 support these observations. Tensile tests on silicone samples showed a softer behavior of the treated ones. Tensile tests on Polyurethane samples showed no significant differences.Polyurethane implants seem to be more resistant to radiotherapy damage, whereas silicone prosthesis showed more structural, mechanical, and chemical modifications
The Effect of Mechanical Thrombectomy on the Incidence of Poststroke Cognitive Impairment: A Systematic Review of Inhomogeneous Literature
Introduction: The aim of this study was to evaluate the effect of mechanical thrombectomy (MT) on the incidence of poststroke cognitive impairment (PSCI) in anterior circulation stroke. Methods: Literature research was performed on PubMed/OVID/Cochrane CENTRAL for studies published in 2015-2022. A review of the references of the included papers was performed for further eligible articles. Clinical characteristics, NIHSS, dementia tests, and outcomes were recorded. The exclusion criteria were nonhuman and non-English. Studies qualities were assessed with MINORS/RoB2 and GRADE. A meta-analysis was performed using the standardized mean difference (Cohen's d) to measure effect size. Results: Four studies were included in the systematic review after screening 749 articles. No significant differences were found for age and gender (years: 66.70 +/- 11.14 vs. 67.59 +/- 10.11, p = 0.37; male 53.8% vs. 56.4%, p = 0.57). MT patients had a more severe stroke than that of the control group (NIHSS: 14.70 +/- 4.31 vs. 11.17 +/- 4.12; p < 0.0001). The control group consisted of medical therapy-alone patients in all studies. I-2 was 76.95%, and Q was 43.4%. MT patients have better performance in overall cognition (d = 0.33 [0.074-0.58]) and in several cognitive domains than in the control group (TMT-A, d = 0.37 [0.04-0.70]; TMT-B, d = 0.35 [0.12-0.58]; digit span test [backward], d = 0.61 [0.18-1.06]; colored progressive matrices, d = 0.48 [0.05-0.91]; Stroop test [word reading], d = 0.60 [0.17-1.03]; color naming, d = 0.51 [0.08-0.94]; Rey-Osterrieth Complex Figure [immediate recall], d = 0.79 [0.35-1.23]; Rey Auditory Verbal Learning Test [immediate recall], d = 0.79 [0.36-1.23]; delayed recall, d = 0.46 [0.035-0.89]; and MOCA, d = 0.46 [-0.04 to 0.96]). Medical therapy patients had a higher score in coping strategy than MT patients (COPE-28 acceptance, d = -1.00 [-1.53 to -0.48]). Conclusions: The incidence of PSCI is lower in MT patients than in the control group. (c) 2023 S. Karger AG, Base
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