Decomposing the site frequency spectrum: the impact of tree topology on neutrality tests

We investigate the dependence of the site frequency spectrum (SFS) on the topological structure of genealogical trees. We show that basic population genetic statistics - for instance estimators of $\theta$ or neutrality tests such as Tajima's $D$ - can be decomposed into components of waiting times between coalescent events and of tree topology. Our results clarify the relative impact of the two components on these statistics. We provide a rigorous interpretation of positive or negative values of an important class of neutrality tests in terms of the underlying tree shape. In particular, we show that values of Tajima's $D$ and Fay and Wu's $H$ depend in a direct way on a peculiar measure of tree balance which is mostly determined by the root balance of the tree. We present a new test for selection in the same class as Fay and Wu's $H$ and discuss its interpretation and power. Finally, we determine the trees corresponding to extreme expected values of these neutrality tests and present formulae for these extreme values as a function of sample size and number of segregating sites.Comment: 23 pages, 8 figure

Studies on tetrafluoropropene-CO2 based gas mixtures for the Resistive Plate Chambers of the ALICE Muon IDentifier

Due to their simplicity and comparatively low cost Resistive Plate Chambers are gaseous detectors widely used in high-energy and cosmic rays physics when large detection areas are needed. However, the best gaseous mixtures are currently based on tetrafluoroethane, which has the undesirable characteristic of a large Global Warming Potential (GWP) of about 1400 and because of this, it is currently being phased out from industrial use. As a possible replacement, tetrafluoropropene (which has a GWP close to 1) has been taken into account. Since tetrafluoropropene is more electronegative than tetrafluoroethane, it has to be diluted with gases with a lower attachment coefficient in order to maintain the operating voltage close to 10 kV. One of the main candidates for this role is carbon dioxide. In order to ascertain the feasibility and the performance of tetrafluoropropene-CO2 based mixtures, an R&D program is being carried out in the ALICE collaboration, which employs an array of 72 Bakelite RPCs (Muon Identifier, MID) to identify muons. Different proportions of tetrafluoropropene and CO2, with the addition of small quantities of isobutane and sulphur hexafluoride, have been tested with 50x50 cm2 RPC prototypes with 2 mm wide gas gap and 2 mm thick Bakelite electrodes. In the presentation, results from tests with cosmic rays will be presented, together with data concerning the current drawn by a RPC exposed to the gamma-ray flux of the Gamma Irradiation Facility (GIF) at CERN.Comment: 4 pages, 3 figures, proceeding of the 12th International Conference on Position Sensitive Detector

The ALICE Experiment Upgrades

The ALICE experiment profited of the Long Shutdown during 2019-2021 in order to expand its physics capabilities and fully profit from the increased LHC luminosity in Run 3. The Inner Tracking System has been replaced with a new silicon tracker based on MAPS technology, and a new tracking device has been added in front of the Muon Spectrometer to improve its vertexing capabilities. The wire chambers for TPC readout have been replaced with new GEM detectors which will minimize ion backflow and allow for continuous data taking: moreover, a new detector array dedicated to fast triggering has been installed. On the software side, a new first pass reconstruction was added in order to handle and reduce the data flow and storage. These upgrades will be presented together with an outlook of the future ALICE upgrades in view of the LHC Run 4, which will include the replacement of the ITS inner tracking layers with upgraded silicon devices and a high-granularity electromagnetic and hadronic calorimeter in the forward direction (FOCAL)Comment: 4 pages, 1 Figure. Proceedings of 32nd Rencontres de Blois conference, October 17-22, 202

Experimental investigation on the mechanical behaviour of AAC blocks for sustainable concrete masonry.

To satisfy the increasing demand of energy efficient buildings, AAC manufacturers are nowadays encouraged to produce blocks with ever lower densities. However, a compromise between energy-saving requirements and mechanical performances is needed to ensure structural safety, as well as an adequate structural durability. This paper reports a comprehensive experimental study on AAC mechanical properties (compressive and tensile strengths, as well as fracture energy), and on their dependency from material density and moisture content. The collected data are compared with some well-known analytical relations taken from the literature, which are often used for the calibration of mechanical parameters required for mathematical and/or finite element modelling of AAC load-bearing masonry, as well as of AAC masonry-infilled framed structures. These comparisons highlight some critical issues in the formulation of analytical relations having a general applicability; however, it was found that RILEM suggestions are appropriate for the considered AAC productions, at least for densities greater than 400 kg/m3

Detecting correlations among functional-sequence motifs

Sequence motifs are words of nucleotides in DNA with biological functions, e.g., gene regulation. Identification of such words proceeds through rejection of Markov models on the expected motif frequency along the genome. Additional biological information can be extracted from the correlation structure among patterns of motif occurrences. In this paper a log-linear multivariate intensity Poisson model is estimated via expectation maximization on a set of motifs along the genome of E. coli K12. The proposed approach allows for excitatory as well as inhibitory interactions among motifs and between motifs and other genomic features like gene occurrences. Our findings confirm previous stylized facts about such types of interactions and shed new light on genome-maintenance functions of some particular motifs. We expect these methods to be applicable to a wider set of genomic features

EVALUATION OF CRACK WIDTH IN RC TIES THROUGH A NUMERICAL "RANGE" MODEL

The problem of cracking in reinforced concrete (RC) tensile members has been studied extensively in the past, not only for the analysis of tension zones, but also for understanding and modeling the behavior of beams in bending. Despite the large number of published studies, there is still no agreement on the relative importance of the most critical parameters influencing crack width and spacing (especially bond-slip and stress diffusion in concrete cover), as proved by the development of more than twenty different formulae available in technical literature [1]. Aim of this work is to investigate if a model based exclusively on bond-slip is able to predict correctly crack width and spacing or if the contribution of stress diffusion in concrete cover - which is included in several design Codes and in some numerical or analytical approaches – must be considered. To this purpose, a one-dimensional numerical model based on bond between steel and concrete is here developed for analyzing the behavior of RC tension ties, by also taking into account the influence of bond deterioration near crack surfaces. To consider the uncertainty of crack pattern evolution, the model provides a range of crack widths and spacing that, according to bond theory, are possible for a given load. The effectiveness of the proposed procedure is verified through comparisons with significant experimental results on RC tension members available in the technical literature [2-3], both in terms of global behavior and in terms of crack width and crack spacing evolution as loading increases. These comparisons prove that bond deterioration improves the results and that the proposed approach can be successfully adopted for design purposes, since it provides a correct estimate of maximum crack width. The obtained results are also compared with Codes provisions and the effectiveness of different approaches for predicting crack width is analyzed and discussed. References [1] Borosnyoi A, Balazs GL. Models for flexural cracking in concrete: the state of the art. Struct Concr, 2005; 6(2): 53-62. [2] Wu HQ, Gilbert RI. An experimental study of tension stiffening in reinforced concrete members under short-term and long-term loads. In: UNICIV Report No. R-449, 2008, The University of New South Wales, Sidney, Australia. [3] Gijsbers FBJ, Hehemann AA. Enige trekproven op gewapend beton (Some tensile tests on reinforced concrete). In: Report BI-77-61, 1977, TNO Inst for Building Mat and Struct, Delft, The Netherlands

Experimental investigation on the mechanical behaviour of AAC blocks for sustainable concrete masonry

To satisfy the increasing demand of energy efficient buildings, AAC manufacturers are nowadays encouraged to produce blocks with ever lower densities. However, a compromise between energy-saving requirements and mechanical performances is needed to ensure structural safety, as well as an adequate structural durability. This paper reports a comprehensive experimental study on AAC mechanical properties (compressive and tensile strengths, as well as fracture energy), and on their dependency from material density and moisture content. The collected data are compared with some well-known analytical relations taken from the literature, which are often used for the calibration of mechanical parameters required for mathematical and/or finite element modelling of AAC load-bearing masonry, as well as of AAC masonry-infilled framed structures. These comparisons highlight some critical issues in the formulation of analytical relations having a general applicability; however, it was found that RILEM suggestions are appropriate for the considered AAC productions, at least for densities greater than 400 kg/m3

Electronic properties of polymer crystals: The effect of interchain interactions

We present a theoretical study of the transport parameters in a prototype conjugated-polymer, poly-para-phenylenevinylene, in two different possible crystalline packings. Our analysis is performed through density-functional electronic structure calculations, and allows one to obtain the fundamental parameters describing charge transport. The transfer integrals are found to be a crucial quantity to appreciate the effects of crystalline aggregation on conduction properties: our results indicate that interchain interactions can be viewed as a tunable parameter for the design of efficient electronic devices based on organic materials.The sensitivity of interchain interactions to the specific three-dimensional (3D) structure was demonstrated. It was confirmed that the interactions can be used to tailor the transport properties of conjugated-polymer films

Repeated successful use of eltrombopag in chronic primary immune thrombocytopenia: description of an intriguing case.

Thrombopoietin receptor agonists (TPO-RAs) are used as effective alternative treatments in ITP patients unresponsive to first-/second-line therapies. TPO- RAs can also be used to normalize platelet count to safely perform invasive pro- cedures and chemotherapy, in case of malignancies. In few responsive patients, TPO-RAs can be suspended maintaining a sustained respons