277 research outputs found
Multiple algebraisations of an elliptic Calogero-Sutherland model
Recently, Gomez-Ullate et al. (1) have studied a particular N-particle
quantum problem with an elliptic function potential supplemented by an external
field. They have shown that the Hamiltonian operator preserves a finite
dimensional space of functions and as such is quasi exactly solvable (QES). In
this paper we show that other types of invariant function spaces exist, which
are in close relation to the algebraic properties of the elliptic functions.
Accordingly, series of new algebraic eigenfunctions can be constructed.Comment: 9 Revtex pages, 3 PS-figures; Summary, abstract and conclusions
extende
FRCM retrofitting techniques for masonry walls: a literature review and some laboratory tests
The experimental characterisation of externally bonded composite materials as strengthening solutions for masonry structures, such as basalt textile reinforced mortar (BTRM) or fiber reinforced concrete (FRC), has been receiving increasing attention due to their outstanding mechanical performance. Several studies have been demonstrated the efficiency of this retrofitting solution for increasing the mechanical strength and the displacement capacity of masonry material. In this paper the state-of-art of the most relevant achievements in the experimental investigations and numerical analysis of retrofitted masonry wall have been critically reviewed. Firstly, a detailed collection of several experimental tests using different textile reinforced mortar and/or fiber reinforced mortar has been conducted. Special focus has been given to the test set-up and load configuration type adopted for experiments. Subsequently, several modelling techniques have been treated in order to detect the best approach simulating the interaction between reinforcement system and masonry ranging from macro and micro modelling, concentrated and diffused plasticity model and diverse constitutive laws. Finally, an overview of some original experimental outcomes from laboratory tests is presented. This results will play a major role in for the validation of the numerical models for the prediction of the shear strength and the ductile behavior of reinforced masonry that will be developed in a further step of this research
Phase transitions in higher derivative gravity and gauge theory: R-charged black holes
This is a continuation of our earlier work where we constructed a
phenomenologically motivated effective action of the boundary gauge theory at
finite temperature and finite gauge coupling on . In this
paper, we argue that this effective action qualitatively reproduces the gauge
theory representing various bulk phases of R-charged black hole with
Gauss-Bonnet correction. We analyze the system both in canonical and grand
canonical ensemble.Comment: 36 pages, 16 figures; v2: typos corrected, references adde
Semi-annual seasonal pattern of serum thyrotropin in adults
Circannual rhythmicity in thyroid-stimulating hormone (TSH) secretion is proposed, whereas evidences on seasonal peripheral thyroid hormones' fluctuation are contradictory. This study was designed to evaluate hypothalamic-pituitary-thyroid (HPT) seasonal secretion pattern using a big data approach. An observational, retrospective, big data trial was carried out, including all TSH measurements performed in a single laboratory between January 2010 and December 2017. A large dataset was created matching TSH data with patients' age, gender, environmental temperature exposure, and free triiodothyronine (fT3) and free thyroxine (fT4) when available. The trend and seasonal distributions were analysed using autoregressive integrated moving average models. A total of 1,506,495 data were included in the final database with patients mean age of 59.00 +/- 18.44 years. The mean TSH serum levels were 2.08 +/- 1.57 microIU/mL, showing a seasonal distribution with higher levels in summer and winter seasons, independently from age, gender and environmental temperatures. Neither fT3 nor fT4 showed a seasonal trend. TSH seasonal changes occurred independently from peripheral thyroid hormone variations, gender, age and environmental temperatures. Although seasonal TSH fluctuation could represent a residual ancestral mechanism to maintain HPT homeostasis, the underlying physiological mechanism remains unclear and specific studies are needed to clarify its impacting role in humans
Horizons and the Thermal Harmonic Oscillator
We show that two-dimensional anti-de Sitter spacetime (AdS_2) can be put in
correspondence, holographically, both with the harmonic oscillator and the free
particle. When AdS_2 has an horizon the corresponding mechanical system is a
thermal harmonic oscillator at temperature given by the Hawking temperature of
the horizon.Comment: Content changed, title slightly modifie
Hematoma esofágico como manifestación atípica de Vasculitis ANCA asociada: reporte de un caso
Las Vasculitis ANCA pueden causar lesiones diversas a lo largo del tracto gastrointestinal pero la afectación esofágica es infrecuente. Dentro del espectro de lesiones que pueden aparecer un hematoma esofágico no es una mención habitual en la bibliografía. Presentamos el caso de una mujer de 67 años con diagnóstico de vasculitis ANCA asociada (VAA) y hematemesis. Consideramos que el hematoma esofágico es una manifestación atípica de una enfermedad infrecuente. La prevalencia real de este tipo de manifestaciones atípicas es des-conocida ya sea por su carácter infrecuente o por la baja tasa de reportes, por lo que creemos es de utilidad la publicación de este tipo de manifestaciones
The “hitchhiker’s guide to the galaxy” of endothelial dysfunction markers in human fertility
Endothelial dysfunction is an early event in the pathogenesis of atherosclerosis and represents the first step in the pathogenesis of cardiovascular diseases. The evaluation of endothelial health is fundamental in clinical practice and several direct and indirect markers have been suggested so far to identify any alterations in endothelial homeostasis. Alongside the known endothelial role on vascular health, several pieces of evidence have demonstrated that proper endothelial functioning plays a key role in human fertility and reproduction. Therefore, this stateof‐the‐art review updates the endothelial health markers discriminating between those available for clinical practice or for research purposes and their application in human fertility. Moreover, new molecules potentially helpful to clarify the link between endothelial and reproductive health are evaluated herein
Causality in AdS/CFT and Lovelock theory
We explore the constraints imposed on higher curvature corrections of the
Lovelock type due to causality restrictions in the boundary of asymptotically
AdS space-time. In the framework of AdS/CFT, this is related to positivity of
the energy constraints that arise in conformal collider physics. We present
explicit analytic results that fully address these issues for cubic Lovelock
gravity in arbitrary dimensions and give the formal analytic results that
comprehend general Lovelock theory. The computations can be performed in two
ways, both by considering a thermal setup in a black hole background and by
studying the scattering of gravitons with a shock wave in AdS. We show that
both computations coincide in Lovelock theory. The different helicities, as
expected, provide the boundaries defining the region of allowed couplings. We
generalize these results to arbitrary higher dimensions and discuss their
consequences on the shear viscosity to energy density ratio of CFT plasmas, the
possible existence of Boulware-Deser instabilities in Lovelock theory and the
extent to which the AdS/CFT correspondence might be valid for arbitrary
dimensions.Comment: 35 pages, 20 figures; v2: minor amendments and clarifications
include
Causality constraints in AdS/CFT from conformal collider physics and Gauss-Bonnet gravity
We explore the relation between positivity of the energy constraints in
conformal field theories and causality in their dual gravity description. Our
discussion involves CFTs with different central charges whose description, in
the gravity side, requires the inclusion of quadratic curvature corrections. It
is enough, indeed, to consider the Gauss-Bonnet term. We find that both sides
of the AdS/CFT correspondence impose a restriction on the Gauss-Bonnet
coupling. In the case of 6d supersymmetric CFTs, we show the full matching of
these restrictions. We perform this computation in two ways. First by
considering a thermal setup in a black hole background. Second by scrutinizing
the scattering of gravitons with a shock wave in AdS. The different helicities
provide the corresponding lower and upper bounds. We generalize these results
to arbitrary higher dimensions and comment on some hints and puzzles they
prompt regarding the possible existence of higher dimensional CFTs and the
extent to which the AdS/CFT correspondence would be valid for them.Comment: 31 pages, 5 figures; v2: typos fixed, cosmetic amendments and
references adde
Intracellular cGMP increase is not involved in thyroid cancer cell death
Introduction: Type 5 phosphodiesterase (PDE5) inhibitors (PDE5i) lead to intracellular cyclic-guanosine monophosphate (cGMP) increase and are used for clinical treatment of erectile dysfunction. Studies found that cGMP may up/downregulate the growth of certain endocrine tumor cells, suggesting that PDE5i could impact cancer risk. Aim: We evaluated if PDE5i may modulate thyroid cancer cell growth in vitro. Materials and methods: We used malignant (K1) and benign (Nthy-ori 3-1) thyroid cell lines, as well as the COS7 cells as a reference model. Cells were treated 0-24 h with the PDE5i vardenafil or the cGMP analog 8-br-cGMP (nM-μM range). cGMP levels and caspase 3 cleavage were evaluated by BRET, in cGMP or caspase 3 biosensor-expressing cells. Phosphorylation of the proliferation-associated extracellularly-regulated kinases 1 and 2 (ERK1/2) was evaluated by Western blotting, while nuclear fragmentation by DAPI staining. Cell viability was investigated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Results: Both vardenafil and 8-br-cGMP effectively induced dose-dependent cGMP BRET signals (p≤0.05) in all the cell lines. However, no differences in caspase 3 activation occurred comparing PDE5i-treated vs untreated cells, at all concentrations and time-points tested (p>0.05). These results match those obtained upon cell treatment with 8-br-cGMP, which failed in inducing caspase 3 cleavage in all the cell lines (p>0.05). Moreover, they reflect the lack of nuclear fragmentation. Interestingly, the modulation of intracellular cGMP levels with vardenafil or the analog did not impact cell viability of both malignant and benign thyroid tumor cell lines, nor the phosphorylation of ERK1/2 (p>0.05). Conclusions: This study demonstrates that increased cGMP levels are not linked to cell viability or death in K1 and Nthy-ori 3-1 cell lines, suggesting that PDE5i do not impact the growth of thyroid cancer cells. Since different results were previously published, further investigations are recommended to clarify the impact of PDE5i on thyroid cancer cells
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