Applications of an exact counting formula in the Bousso-Polchinski Landscape

The Bousso-Polchinski (BP) Landscape is a proposal for solving the Cosmological Constant Problem. The solution requires counting the states in a very thin shell in flux space. We find an exact formula for this counting problem which has two simple asymptotic regime one of them being the method of counting low $\Lambda$ states given originally by Bousso and Polchinski. We finally give some applications of the extended formula: a robust property of the Landscape which can be identified with an effective occupation number, an estimator for the minimum cosmological constant and a possible influence on the KKLT stabilization mechanism.Comment: 43 pages, 11 figures, 2 appendices. We have added a new section (3.4) on the influence of the fraction of non-vanishing fluxes in the KKLT mechanism. Other minor changes also mad

Fragmentos de inscripciones monumentales romanas de Sagunto

Unas excavaciones arqueológicas en la ciudad de Sagunto han aportado, entre otros materiales, diversos fragmentos de tres inscripciones monumentales. Su estudio demuestra que estamos ante piezas que reflejan importantes aspectos de la vida romana saguntina de época imperial. Así, en la primera de ellas podría tratarse de una referencia al culto de Mitra, mientras en las otras dos se aludiría a algún prominente personaje público.Some archaeological excavations in the city of Saguntum have recovered, among other materials, to different fragments of three monumental inscriptions. Their study shows important aspects of urban life on Roman imperial period. Thus, the first of them could be a reference to the cult of Mithras, while the other two could allude to distinguished public person

Stabilized updated Lagrangian corrected SPH for explicit dynamic problems

This is the pre-peer reviewed version of the following article:Vidal, Y.; Bonet, J.; Huerta, A. Stabilized updated Lagrangian corrected SPH for explicit dynamic problems. "International journal for numerical methods in engineering", Març 2007, vol. 69, núm. 13, p. 2687-2710, which has been published in final form at http://www3.interscience.wiley.com/journal/112777203/abstractSmooth Particle Hydrodynamics with a total Lagrangian formulation are, in general, more robust than nite elements for large distortion problems. Nevertheless, updating the reference con¯guration may still be necessary in some problems involving extremely large distortions. However, as discussed here a standard updated formulation suffers the presence of zero energy modes that are activated and may spoil completely the solution. It is important to note that, unlike an Eulerian formulation,the updated Lagrangian does not present tension instability but only zero energy modes. Here an stabilization technique is incorporated to the updated formulation to obtain an improved method without mechanisms and capable to solve problems with extremely large distortions.Peer ReviewedPostprint (author’s final draft

Encoding the scaling of the cosmological variables with the Euler Beta function

We study the scaling exponents for the expanding isotropic flat cosmological models. The dimension of space, the equation of state of the cosmic fluid and the scaling exponent for a physical variable are related by the Euler Beta function that controls the singular behavior of the global integrals. We encounter dual cosmological scenarios using the properties of the Beta function. For the entropy density integral we reproduce the Fischler-Susskind holographic bound.Comment: Latex2e, 11 pages, 1 figure; reference added; minor changes commenting the nature of the holographic principle and the particle/event horizo

Reverse engineering applied to biomodelling and pathological bone manufacturing using FDM technology

[EN] Reverse engineering and medical image-based modeling technologies allow manufacturing of 3D biomodels of anatomical structures of human body. These techniques are based on anatomical information from scanning data such as CT and MRI, whose scanners are used for scanning data acquisition of the external and internal geometry of anatomical structures. These 3D biomodels have many medical applications such surgical training, preoperative planning, surgical simulation, diagnosis and treatments. 3D virtual models of human body structures based on CT are increasingly being used in clinical practice. A data processing methodology is required to obtain an accurate 3D model suitable for manufacturing using AM, and specially the FDM technologies. This study shows a step-by-step methodology to process the CT information in bounded uncertainty conditions in order to obtain the STL models of the degenerated bone components, and to manufacture the 3D biomodels for surgery analysis with optimal design and details, and with an adequate accuracy to ensure proper results by surgeons analysis.The authors wish to acknowledge the support of Ms. Jerica Risent and Mr. Joan Ortiz of Ford Motor Company for his assistance in the scanning of printed models. This work was supported by the Polisabio Funding (UPV-Fisabio 2017)Laura Piles; Miguel J. Reig; Vte. Jesús Seguí; Rafael Pla; Fernando Martínez; José Miguel Seguí (2019). Reverse engineering applied to biomodelling and pathological bone manufacturing using FDM technology. Procedia Manufacturing. 41:739-746. https://doi.org/10.1016/j.promfg.2019.09.065S73974641Van Eijnatten, M., Berger, F. H., de Graaf, P., Koivisto, J., Forouzanfar, T., & Wolff, J. (2017). Influence of CT parameters on STL model accuracy. Rapid Prototyping Journal, 23(4), 678-685. doi:10.1108/rpj-07-2015-0092Lalone, E. A., Willing, R. T., Shannon, H. L., King, G. J. W., & Johnson, J. A. (2015). Accuracy assessment of 3D bone reconstructions using CT: an intro comparison. Medical Engineering & Physics, 37(8), 729-738. doi:10.1016/j.medengphy.2015.04.010Stull, K. E., Tise, M. L., Ali, Z., & Fowler, D. R. (2014). Accuracy and reliability of measurements obtained from computed tomography 3D volume rendered images. Forensic Science International, 238, 133-140. doi:10.1016/j.forsciint.2014.03.005Van Eijnatten, M., van Dijk, R., Dobbe, J., Streekstra, G., Koivisto, J., & Wolff, J. (2018). CT image segmentation methods for bone used in medical additive manufacturing. Medical Engineering & Physics, 51, 6-16. doi:10.1016/j.medengphy.2017.10.008Javaid, M., & Haleem, A. (2018). Additive manufacturing applications in medical cases: A literature based review. Alexandria Journal of Medicine, 54(4), 411-422. doi:10.1016/j.ajme.2017.09.003D.V.C. Stoffelen, K. Eraly, P. Debeer, The use of 3D printing technology in reconstruction of a severe glenoid defect: a case report with 2.5 years of follow-up, Journal of Shoulder Elbow Surgery, 24 (2015) e218-e22

Exploring a simple sector of the Einstein-Maxwell landscape

We explore the four dimensional Einstein-Maxwell landscape as a toy model in which we can formulate a sphere compactification stabilized by an electromagnetic field. Replacing the compactification sphere by J spheres, we obtain a simple sector of the (2J+2)-dimensional Einstein-Maxwell landscape. In this toy model, we analyze some properties which are very difficult to uncover in the string theory landscape, including: complete moduli stabilization, stability conditions, and state counting. We also show how to construct anthropic states in this model. A detailed comparison between the main features of this landscape and the Bousso-Polchinski landscape is given. We finally speculate on the impact of these phenomena in the string theory landscape.Comment: 69 pages, 16 figures, some references adde

Gaseous time projection chambers for rare event detection: Results from the T-REX project. II. Dark matter

As part of the T-REX project, a number of R&D and prototyping activities have been carried out during the last years to explore the applicability of Micromegas-read gaseous TPCs in rare event searches like double beta decay (DBD), axion research and low-mass WIMP searches. While in the companion paper we focus on DBD, in this paper we focus on the results regarding the search for dark matter candidates, both axions and WIMPs. Small ultra-low background Micromegas detectors are used to image the x-ray signal expected in axion helioscopes like CAST at CERN. Background levels as low as $0.8\times 10^{-6}$ c keV$^{-1}$cm$^{-2}$s$^{-1}$ have already been achieved in CAST while values down to $\sim10^{-7}$ c keV$^{-1}$cm$^{-2}$s$^{-1}$ have been obtained in a test bench placed underground in the Laboratorio Subterr\'aneo de Canfranc. Prospects to consolidate and further reduce these values down to $\sim10^{-8}$ c keV$^{-1}$cm$^{-2}$s$^{-1}$will be described. Such detectors, placed at the focal point of x-ray telescopes in the future IAXO experiment, would allow for 10$^5$ better signal-to-noise ratio than CAST, and search for solar axions with $g_{a\gamma}$ down to few 10$^{12}$ GeV$^{-1}$, well into unexplored axion parameter space. In addition, a scaled-up version of these TPCs, properly shielded and placed underground, can be competitive in the search for low-mass WIMPs. The TREX-DM prototype, with $\sim$0.300 kg of Ar at 10 bar, or alternatively $\sim$0.160 kg of Ne at 10 bar, and energy threshold well below 1 keV, has been built to test this concept. We will describe the main technical solutions developed, as well as the results from the commissioning phase on surface. The anticipated sensitivity of this technique might reach $\sim10^{-44}$ cm$^2$ for low mass ($<10$ GeV) WIMPs, well beyond current experimental limits in this mass range.Comment: Published in JCAP. New version with erratum incorporated (new figure 14