Foliations and 2+1 Causal Dynamical Triangulation Models

The original models of causal dynamical triangulations construct space-time by arranging a set of simplices in layers separated by a fixed time-like distance. The importance of the foliation structure in the 2+1 dimensional model is studied by considering variations in which this property is relaxed. It turns out that the fixed-lapse condition can be equivalently replaced by a set of global constraints that have geometrical interpretation. On the other hand, the introduction of new types of simplices that puncture the foliating sheets in general leads to different low-energy behavior compared to the original model.Comment: v2: 9 pages, 3 figures, published versio

Quantum vacuum effects from boundaries of designer potentials

Vacuum energy in quantum field theory, being the sum of zero-point energies of all field modes, is formally infinite but yet, after regularization or renormalization, can give rise to finite observable effects. One way of understanding how these effects arise is to compute the vacuum energy in an idealized system such as a large cavity divided into disjoint regions by pistons. In this paper, this type of calculation is carried out for situations where the potential affecting a field is not the same in all regions of the cavity. It is shown that the observable parts of the vacuum energy in such potentials do not fall off to zero as the region where the potential is nontrivial becomes large. This unusual behavior might be interesting for tests involving quantum vacuum effects and for studies on the relation between vacuum energy in quantum field theory and geometry.Comment: 13 pages, 2 figure

A Field Theory Model With a New Lorentz-Invariant Energy Scale

A framework is proposed that allows to write down field theories with a new energy scale while explicitly preserving Lorentz invariance and without spoiling the features of standard quantum field theory which allow quick calculations of scattering amplitudes. If the invariant energy is set to the Planck scale, these deformed field theories could serve to model quantum gravity phenomenology. The proposal is based on the idea, appearing for example in Deformed Special Relativity, that momentum space could be curved rather than flat. This idea is implemented by introducing a fifth dimension and imposing an extra constraint on physical field configurations in addition to the mass shell constraint. It is shown that a deformed interacting scalar field theory is unitary. Also, a deformed version of QED is argued to give scattering amplitudes that reproduce the usual ones in the leading order. Possibilities for experimental signatures are discussed, but more work on the framework's consistency and interpretation is necessary to make concrete predictions.Comment: 20 page

Matter in Toy Dynamical Geometries

One of the objectives of theories describing quantum dynamical geometry is to compute expectation values of geometrical observables. The results of such computations can be affected by whether or not matter is taken into account. It is thus important to understand to what extent and to what effect matter can affect dynamical geometries. Using a simple model, it is shown that matter can effectively mold a geometry into an isotropic configuration. Implications for "atomistic" models of quantum geometry are briefly discussed.Comment: 8 pages, 1 figure, paper presented at DICE 200

The Free Particle in Deformed Special Relativity

The phase space of a classical particle in DSR contains de Sitter space as the space of momenta. We start from the standard relativistic particle in five dimensions with an extra constraint and reduce it to four dimensional DSR by imposing appropriate gauge fixing. We analyze some physical properties of the resulting theories like the equations of motion, the form of Lorentz transformations and the issue of velocity. We also address the problem of the origin and interpretation of different bases in DSR.Comment: 15 page

Statistical Mechanics of Graphity Models

Graphity models are characterized by configuration spaces in which states correspond to graphs and Hamiltonians that depend on local properties of graphs such as the degrees of vertices and numbers of short cycles. As statistical systems, graphity models can be studied analytically by estimating their partition functions or numerically by Monte Carlo simulations. Results presented here are based on both of these approaches and give new information about the high- and low-temperature behavior of the models and the transitions between them. In particular, it is shown that matter degrees of freedom must play an important role in order for the low-temperature regime to be described by graphs resembling interesting extended geometries.Comment: 30 pages, 8 figures; v2. minor change

Periodontitis and risk for preeclampsia — a systematic review

Objectives: The aim of the study is to review systematic cohort and randomized trials on the relationship between periodontitis and preeclampsia. Periodontitis is an independent risk factor for preeclampsia (PE), and periodontal treatment could play a significant role in the prevention of this pregnancy complication. Material and methods: A total of 821 items (published until March 2019), thematically related to the relationship between periodontitis, its treatment and the incidence of preeclampsia, were collected from the databases of PubMed, Scopus, Google Scholar and the Polish Database of Medical Bibliography and analyzed. In the end, 6 cohort studies and 3 randomized controlled trials (from the years 2003–2016) were deemed eligible for the review. The main exclusion criteria were as follows: case-control and cross-sectional studies, medical and dental conditions. Results: A significant relationship between periodontitis and the risk for developing preeclampsia was demonstrated in 5 cohort trials, which was not confirmed by only 1 study. A total of 2724 pregnant women, including 195 (7.16%) with PE, were analyzed. In 3 randomized trials which assessed the impact of non-surgical treatment (scaling and root planing = SRP) on the occurrence of preeclampsia, the preventive effects of the implemented treatment was not confirmed. A total of 116 women from the group of 1825 pregnant subjects undergoing the non-surgical treatment (SRP) and 116 women from the control group of 1827 pregnant women were subsequently diagnosed with PE, which amounted to 6.30% and 6.35%, respectively. Conclusions: The cohort studies indicated that periodontitis may result in an increased risk for developing PE. A more detailed analysis regarding the impact of potential risk factors and modification of further studies (clarification of how periodontitis and preeclampsia should be defined in observations, consideration of disease severity, earlier at 12–16 weeks of gestation — implementation of the non-surgical treatment, modification and extension of the classical protocol of the non-surgical treatment of periodontal diseases, as well as conducting European studies), are necessary due to considerable discrepancies in the available literature sources (cohort and randomized observations)

Comparison of genetic variants in matched samples using thesaurus annotation

Motivation: Calling changes in DNA, e.g. as a result of somatic events in cancer, requires analysis of multiple matched sequenced samples. Events in low-mappability regions of the human genome are difficult to encode in variant call files and have been under-reported as a result. However, they can be described accurately through thesaurus annotation - a technique that links multiple genomic loci together to explicate a single variant. Results: We here describe software and benchmarks for using thesaurus annotation to detect point changes in DNA from matched samples. In benchmarks on matched normal/tumor samples we show that the technique can recover between five and ten percent more true events than conventional approaches, while strictly limiting false discovery and being fully consistent with popular variant analysis workflows. We also demonstrate the utility of the approach for analysis of de novo mutations in parents/child families. Availability and Implementation: Software performing thesaurus annotation is implemented in java; available in source code on github at GeneticThesaurus and as an executable on sourceforge at geneticthesaurus. Mutation calling is implemented in an R package available on github at RGeneticThesaurus