345 research outputs found

    Symmetric scalars

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    We provide a complete classification of Poincar\'e-invariant scalar field theories with an enlarged set of classical symmetries to leading order in derivatives, namely for the so-called P(X,ϕ)P(X,\phi) theories, in two or more spacetime dimensions. We find only three possibilities: Dirac-Born-Infeld, Cuscuton and Scaling theories. The latter two classes of actions involve an arbitrary function of the scalar field. As an application, we use the scaling symmetry to derive an infinite set of constraints on the Wilsonian coefficients of the low-energy Effective Field Theory. Furthermore, we study the extension of these results to cosmological (FLRW) and (Anti-)de Sitter spacetimes. We find in particular that the Cuscuton action has a generic set of symmetries around any background spacetime that possesses Killing vector fields, while the DBI actions have well-known analogues that we summarize explicitly

    A dynamic auto-adaptive predictive maintenance policy for degradation with unknown parameters

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    International audienceWith the development of monitoring equipment, research on condition-based maintenance (CBM) is rapidly growing. CBM optimization aims to find an optimal CBM policy which minimizes the average cost of the system over a specified duration of time. This paper proposes a dynamic auto-adaptive predictive maintenance policy for single-unit systems whose gradual deterioration is governed by an increasing stochastic process. The parameters of the degradation process are assumed to be unknown and Bayes' theorem is used to update the prior information. The time interval between two successive inspections is scheduled based on the remaining useful life (RUL) of the system and is updated along with the degradation parameters. A procedure is proposed to dynamically adapt the maintenance decision variables accordingly. Finally, different possible maintenance policies are considered and compared to illustrate their performance

    De novo atrial fibrillation as an independent prognostic marker after ST-segment elevation myocardial infarction: Results from the RIMA registry

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    BACKGROUND: Atrial fibrillation (AF) is common in ST-segment elevation myocardial infarction (STEMI), but its influence on prognosis remains controversial. AIM: We examined the 1-year prognostic value of AF in STEMI, distinguishing patients with prior AF from patients with de novo AF. METHODS: Between January 2004 and December 2015, 3173 STEMI patients were enrolled in the RIMA registry (Registre des Infarctus en Maine Anjou). They were divided into 3 groups: (1) AF-free patients; (2) patients with known prior AF; and (3) patients with de novo AF during hospitalization (including admission). We defined 3 primary outcomes at 1-year post-discharge: cardiovascular mortality, readmission for heart failure (HF), and stroke. Temporal onset of de novo AF was also studied. RESULTS: A total 158 patients (5%) had prior AF, and 278 (8.8%) presented de novo AF. Prior AF patients were significantly older [81 (73;86) years] with more comorbidities, but de novo AF patients presented with a greater creatine kinase peak and lower left ventricular ejection fraction [LVEF=44 (35;50)% for de novo AF vs 50 (40;55)% for prior AF, p<0.001]. At 1-year follow-up, cardiovascular mortality was higher in cases of AF (13.5% for prior AF vs 9.2% for de novo AF, compared with 2.4% for AF-free patients, p<0.001). After adjustments, only de novo AF was correlated with cardiovascular mortality (hazard ratio 2.49; 95% CI 1.32-4.67; p=0.004), but both types of AF were correlated with readmission for HF. There was no significant difference in respect of stroke between prior AF, de novo AF, and AF-free (2.2%, 0.5%, and 0.8%, respectively, p=0.327). Finally, outcomes did not differ between AF occurring <24h after admission (n=127) and de novo AF occurring within ≥24h (n=151). CONCLUSION: De novo AF was independently associated with 1-year cardiovascular mortality. It should not be considered as an intercurrent event of STEMI, but rather as a strong prognostic marker

    Moho depth and crustal thinning in the Marmara Sea region from gravity data inversion

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    The free‐air gravity in the Marmara Sea reveals that the low density of sedimentary basins is partly compensated in the lower crust. We compiled geophysical upper crust studies to determine the sediment basin geometries in and around the Marmara Sea and corrected the gravity signal from this upper crust geology with the Parker method. Then, assuming long wavelength anomalies in the residual gravity signal is caused by variations in the Moho topography, we inverted the residual to build the Moho topography. The result shows that the Moho is uplifted on an area greater than the Marmara Sea with a maximum crust thinning beneath the basins where the Moho is at about 25 km, 5 km above the reference depth. We then evaluated the Neogene extension by comparing the surface covered by our 3‐D thinned model with the surface covered by an unthinned model with same crustal volume. Comparing this surface with areal extension rate from GPS data, we found a good compatibility indicating that the extension rate averaged over the Sea of Marmara area probably remained close to its present‐day value during major changes of tectonic regime, as the incursion of the North Anatolian Fault system during the Pliocene leads to the establishment of the dominantly strike‐slip present‐day system. We also show that crustal extension is distributed over a wider domain in the lower crust than in the upper crust, and that this may be accounted for by a relatively minor component of lower crustal ductile flow

    Ric-8A, a Gα Protein Guanine Nucleotide Exchange Factor Potentiates Taste Receptor Signaling

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    Taste receptors for sweet, bitter and umami tastants are G-protein-coupled receptors (GPCRs). While much effort has been devoted to understanding G-protein-receptor interactions and identifying the components of the signalling cascade downstream of these receptors, at the level of the G-protein the modulation of receptor signal transduction remains relatively unexplored. In this regard a taste-specific regulator of G-protein signaling (RGS), RGS21, has recently been identified. To study whether guanine nucleotide exchange factors (GEFs) are involved in the transduction of the signal downstream of the taste GPCRs we investigated the expression of Ric-8A and Ric-8B in mouse taste cells and their interaction with G-protein subunits found in taste buds. Mammalian Ric-8 proteins were initially identified as potent GEFs for a range of Gα subunits and Ric-8B has recently been shown to amplify olfactory signal transduction. We find that both Ric-8A and Ric-8B are expressed in a large portion of taste bud cells and that most of these cells contain IP3R-3 a marker for sweet, umami and bitter taste receptor cells. Ric-8A interacts with Gα-gustducin and Gαi2 through which it amplifies the signal transduction of hTas2R16, a receptor for bitter compounds. Overall, these findings are consistent with a role for Ric-8 in mammalian taste signal transduction

    Proteomic Identification of Interleukin-2 Therapy Response in Metastatic Renal Cell Cancer

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    Introduction—To detect a predictive protein profile that distinguishes between IL-2 therapy responders and non-responders among metastatic RCC patients we used surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI TOF-MS). Materials and Methods—Protein extracts of 56 metastatic clear cell RCC patients obtained from radical nephrectomy specimens and prior to IL-2 therapy were applied to protein chip arrays of different chromatographic properties and analyzed using SELDI TOF-MS. A class prediction algorithm was applied to identify a subset of protein peaks whose expression values were associated with IL-2 response status. Multivariate analysis was performed to assess the association between the proteomic profile and the IL-2 response status controlling for the effect of lymphadenopathy. Results—From a total of 513 protein peaks we discovered a predictor set of 11 peaks that performed optimally for predicting IL-2 response status (86 % accuracy, Fisher’s p\u3c0.004, permutation p\u3c0.01). The results were validated on an independent data set with an overall accuracy of 72% (p \u3c 0.05, permutation p\u3c0.01). On multivariate analysis the proteomic profile was significantly associated with IL-2 response when corrected for lymph node status (p\u3c 0.04). Conclusions—We have identified and validated a proteomic pattern that is an independent predictor of IL-2 response. The ability to predict the probability of IL-2 response could permit targeted selection of patients most likely to respond to IL-2, while avoiding unwanted toxicities in patients less likely to respond. This proteomic predictor has the potential to significantly aid clinicians in the decision making of appropriate therapy for metastatic RCC patients

    Endoplasmic reticulum stress pathway involvement in local and remote myocardial ischemic conditioning.

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    Remote ischemic perconditioning (RIPer) and local ischemic postconditioning (IPost) are promising methods to decrease ischemia-reperfusion injury. We tested whether these two methods were effective in reducing infarct size through activation of endoplasmic reticulum (ER) stress response, a potential survival pathway. Rats exposed to myocardial ischemia-reperfusion were allocated to one of six groups: control, no intervention at myocardial reperfusion; IPost, three cycles of 10-s coronary artery occlusion followed by 10-s reperfusion applied at the onset of myocardial reperfusion; RIPer, 10-min limb ischemia followed by 10-min reperfusion initiated during coronary artery occlusion; control + 4-PBA, injection of ER stress inhibitor 4-phenylbutyrate (4-PBA) 1 h before coronary occlusion; IPost + 4-PBA; and RIPer + 4-PBA. Infarct size was significantly reduced in IPost and RIPer groups (33.32% ± 3.65% and 21.86% ± 3.98%, respectively) compared with the control group (54.86% ± 6.01%, P < 0.05). Western blot analysis of GRP78 (glucose-regulated protein) level and cleaved activating transcription factor 6, two ER stress markers, demonstrated an enhancement of ER stress response in IPost group but not in RIPer group at 15-min reperfusion. Furthermore, 4-PBA abolished cardioprotection induced by IPost (infarct size 53.75 ± 3.49 vs. 33.32 ± 3.65%, P < 0.05) but not by RIPer (28.80 ± 10.45% vs. 21.86 ± 3.98%, not statistically significant). GRP78 and cleaved activating transcription factor 6 levels were no longer increased in IPost group after 4-PBA. These findings point to a role for ER stress response in cardioprotection against reperfusion injury in IPost but not RIPer, suggesting differences in cardioprotective mechanisms between local and remote conditioning

    Gas and seismicity within the Istanbul seismic gap

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    Understanding micro-seismicity is a critical question for earthquake hazard assessment. Since the devastating earthquakes of Izmit and Duzce in 1999, the seismicity along the submerged section of North Anatolian Fault within the Sea of Marmara (comprising the “Istanbul seismic gap”) has been extensively studied in order to infer its mechanical behaviour (creeping vs locked). So far, the seismicity has been interpreted only in terms of being tectonic- driven, although the Main Marmara Fault (MMF) is known to strike across multiple hydrocarbon gas sources. Here, we show that a large number of the aftershocks that followed the M 5.1 earthquake of July, 25th 2011 in the western Sea of Marmara, occurred within a zone of gas overpressuring in the 1.5–5 km depth range, from where pressurized gas is expected to migrate along the MMF, up to the surface sediment layers. Hence, gas-related processes should also be considered for a complete interpretation of the micro- seismicity (~M < 3) within the Istanbul offshore domain
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