Quantization of Weyl invariant unimodular gravity with antisymmetric ghost fields

The enforcement of the unimodularity condition in a gravity theory by means of a Lagrange multiplier leads, in general, to inconsistencies upon quantization. This is so, in particular, when the classic linear splitting of the metric between the background and quantum fields is used. To avoid the need of introducing such a Lagrange multiplier while using the classic linear splitting, we carry out the quantization of unimodular gravity with extra Weyl symmetry by using Becchi-Rouet-Stora-Tyutin (BRST) techniques. Here, two gauge symmetries are to be gauge-fixed: transverse diffeomorphisms and Weyl transformations. We perform the gauge-fixing of the transverse diffeomorphism invariance by using BRST transformations that involve antisymmetric ghost fields. We show that these BRST transformations are compatible with the BRST transformations needed to gauge-fix the Weyl symmetry, so that they can be combined in a set of transformations generated by a single BRST operator. Newton's law of gravitation is derived within the BRST formalism we put forward as well as the Slavnov-Taylor equation.Comment: 24 pages, 1 table, 1 figur

Methane hydrate: shifting the coexistence temperature to higher temperatures with an external electric field

In the present work, we used molecular dynamic simulations of the equilibrium NPT ensemble to examine the effect of an external electric field on the three-phase coexistence temperature of methane gas, liquid water and methane hydrate. For these simulations, we used the TIP4P/Ice rigid water model and a single-site model for methane. The simulations were implemented at two pressures, 400 and 250bar, over temperatures ranging from 285 to 320K and from 280 to 315K, respectively. The application of an external electric field in the range of 0.1-0.9caused the effect of the thermal vibrations of the water molecules to become attenuated. This resulted in a shift of the three-phase coexistence temperature to higher temperatures. Electric fields below this range did not cause a difference in the coexistence temperature, and electric fields above this range enhanced the thermal effect. The shift had a magnitude of 22.5K on average.Peer ReviewedPostprint (author's final draft

HERA prospects on Compositeness and New Vector Bosons

The absence of deviations from the Standard Model for the differential cross section ${d\sigma}/{dQ^2}$ at HERA is used to set limits on electron quark compositeness scale and on new vector bosons, especially the hadrophilic one recently introduced as a possible explanation for LEP/SLC and CDF anomalies.Comment: Latex file, 7 pages and 1 ps fig, few comments on others experiments are added, results are unchanged. To appear in Phys. Let.

Wiping DNA Methylation: Wip1 Regulates Genomic Fluidity on Cancer

Wip1 phosphatase plays an important role in cancer by inactivating p53 and INK4a/ARF pathways. In this issue of Cancer Cell, Filipponi and colleagues further connect the oncogenic role of Wip1 with heterochromatin dynamics, transposable element expression, and a mutation-prone environment that may enhance heterogeneity and ultimately contribute to tumor evolution

AI-driven web API testing

Testing of web APIs is nowadays more critical than ever before, as they are the current standard for software integration. A bug in an organization’s web API could have a huge impact both in ternally (services relying on that API) and externally (third-party applications and end users). Most existing tools and testing ap proaches require writing tests or instrumenting the system under test (SUT). The main aim of this dissertation is to take web API testing to an unprecedented level of automation and thoroughness. To this end, we plan to apply artificial intelligence (AI) techniques for the autonomous detection of software failures. Specifically, the idea is to develop intelligent programs (we call them “bots”) ca pable of generating hundreds, thousands or even millions of test inputs and to evaluate whether the test outputs are correct based on: 1) patterns learned from previous executions of the SUT; and 2) knowledge gained from analyzing thousands of similar programs. Evaluation results of our initial prototype are promising, with bugs being automatically detected in some real-world APIs.Ministerio de Economía y Competitividad BELI (TIN2015-70560-R)Ministerio de Ciencia, Innovación y Universidades RTI2018-101204-B-C21 (HORATIO)Ministerio de Educación, Cultura y Deporte FPU17/0407

The envelope of IRC+10216 reflecting the galactic light: UBV surface brightness photometry and interpretation

We present and analyse new optical images of the dust envelope surrounding the high mass-loss carbon star IRC+10216. This envelope is seen due to external illumination by galactic light. Intensity profiles and colors of the nebula were obtained in the UBV bandpasses. The data are compared with the results of a radiative transfer model calculating multiple scattering of interstellar field photons by dust grains with a single radius. The data show that the observed radial shape of the nebula, especially its half maximum radius, does not depend on wavelength (within experimental errors), suggesting that grains scatter in the grey regime, etc, etc (this abstract has been shortened)Comment: accepted by A

Study of different titanosilicate (TS-1 and ETS-10) as fillers for Mixed Matrix Membranes for CO2/CH4 gas separation applications

Three titanosilicate zeolites were used as fillers for Mixed Matrix Membranes: (i) ETS-10, TS-1 having Si/Ti=100 and (iii) TS-1 using Si/Ti=25. Zeolite samples were characterized by X-Ray Diffraction, Scanning Electron Microscopy, Atomic Emission Spectroscopy, X-Ray Photoelectron Spectroscopy, and CO2 and CH4 adsorption isotherms. TS-1 particles showed a narrow size distribution ranging from 200 nm to 400 nm. In the case of ETS-10, the size distribution was broader ranging from 400 nm to 800 nm. Mixed Matrix Membranes were prepared using Matrimid (R) polyimide as continuous phase and filler loadings of 10, 20, and 30 wt%. Membranes were characterized by Thermogravimetric Analysis, Differential Scanning Calorimetry, and Scanning Electron Microscopy. The performances was measured at 8 bars of transmembrane pressure for CO2/CH4 mixed gases system at 50/50 vol/vol. concentration. Membranes using TS-1 (Si/Ti=25) as filler showed a maximum increase of 89.1% of CO2 permeability and 23.9% increase in separation factor. In the case of TS-1 (Si/Ti=100) only permeability increased significantly, with a maximum increase of 90.1%. Regarding the ETS-10 membranes, both permeability and separation factor increased slightly with respect to the reference polymeric membrane (22.5% in CO2 permeability and 7.8% in the separation factor). In conclusion, TS-1 (Si/Ti=25) is the most suitable filler for the use in Mixed Matrix Membranes for gas separation applications among the titanosilicate studied in this work