Dalitz Plot Study of the Charmless Decay B+ -> Ks pi + pi0 with the BABAR Detector

This thesis presents preliminary measurements of decays of B mesons in charmless final states, by using a data sample of 365 millions of B+B- pairs collected by the BABAR detector at the PEP-II Asymmetric B Factory, located at the Stanford Linear Accelerator Center. The three-body meson decays are more complicated than two-body decays as they receive resonant and non-resonant contributions. They are generally dominated by intermediate vector and scalar resonances, namely, they proceed via quasi-two-body decays containing a resonance state and a pseudoscalar meson. Indeed, most of the quasi-twobody B decays are extracted from the analysis of three-body B decays using the Dalitz plot technique, in order to study the properties of various resonances. The study of charmless hadronic B decays can make important contributions to the understanding of models of hadronic decays. The Dalitz plot analysis of three-body B decays provides a nice methodology for extracting information on the unitary triangle in the standard model and can help the understanding of CP violation. Studies of charmless three-body decays system combined with theoretical assumption, allow to put constraints on g angle of the Cabibbo-Kobayashi-Maskawa matrix. This is the first study of the charmless decay of the charged B meson into three-bodyfinal state Ks pi+ pi0. This thesis is organized as follows. The theory of the three-body charmless decays is reviewed in Chapter 1, together with a brief reminder of CP violation. Chapter 2 presents an overview of the BABAR detector used to collect the data studied in the analysis. The experimental techniques used to reconstruct events and identify particles are presented in Chapter 3. The studies performed on the Monte Carlo in order to discriminate the signal from the backgrounds are collected in Chapter 4. In Chapter 5 the steps done to validate the fitter are discussed, and the final fit on the data is presented. Chapter 6 presents the evaluation of systematic uncertainties. In Chapter 7 we show the results for branching ratios and CP asymmetries for the three-body decay under study. The results presented in this thesis are preliminary and show the potential capabilities that can be obtained with the BABAR dataset

Does divergence from normal patterns of integration increase as chromosomal fusions increase in number? A test on a house mouse hybrid zone

Chromosomal evolution is widely considered an important driver of speciation because it can promote the establishment of reproductive barriers. Karyotypic reorganization is also expected to affect the mean phenotype, as well as its development and patterns of phenotypic integration, through processes such as variation in genetic linkage between QTL regions or between regulatory regions and their targets. Here we explore the relationship between chromosomal evolution and phenotypic integration by analysing a well-known house mouse parapatric contact zone between a highly derived Robertsonian race (2n = 22) and populations with standard karyotype (2n = 40). Populations with hybrid karyotypes are scattered throughout the hybrid zone connecting the two parental races. Using mandible shape data and geometric morphometrics, we test the hypothesis that patterns of integration progressively diverge from the “normal” integration pattern observed in the standard race as they accumulate Robertsonian fusions. We find that the main pattern of integration observed between the posterior and anterior part of the mandible can be largely attributed to allometry. We find no support for a gradual increase in divergence from normal patterns of integration as fusions accumulate. Surprisingly, however, we find that the derived Robertsonian race (2n = 22) has a distinct allometric trajectory compared to the standard race. Our results suggest that either individual fusions disproportionately affect patterns of integration or that there are mechanisms which “purge” extreme variants in hybrids (e.g., reduced fitness of hybrid shape).publishe

Divergent allometric trajectories in gene expression and coexpression produce species differences in sympatrically speciating Midas cichlid fish

The mechanisms of speciation without geographic isolation (i.e., sympatric speciation) remain debated. This is due in part to the fact that the genomic landscape that could promote or hinder species divergence in the presence of gene flow is still largely unknown. However, intensive research is now centered on understanding the genetic architecture of adaptive traits associated with this process as well as how gene expression might affect these traits. Here, using RNAseq data, we investigated gene expression of sympatrically speciating benthic and limnetic Neotropical cichlid fishes at two developmental stages. First, we identified groups of co-expressed genes (modules) at each stage. While there are a few large and well-preserved modules, most of the other modules are not preserved across life stages. Second, we show that later in development more and larger co-expression modules are associated with divergence between benthic and limnetic fish compared to the earlier life stage. This divergence between benthic and limnetic fish in co-expression mirrors divergence in overall expression between benthic and limnetic fish, which is more pronounced later in life. Our results reveal that already at one-day post-hatch benthic and limnetic fish diverge in (co)expression, and that this divergence becomes more substantial when fish are free-swimming but still unlikely to have divergent swimming and feeding habits. More importantly, our study describes how the co-expression of several genes through development, as opposed to individual genes, is associated with benthic-limnetic species differences, and how two morphogenetic trajectories diverge as fish grow older.publishe

Using Independent Component Analysis to detect exoplanet reflection spectrum from composite spectra of exoplanetary binary systems

The analysis of the wavelength-dependent albedo of exoplanets represents a direct way to provide insight of their atmospheric composition and to constrain theoretical planetary atmosphere modelling. Wavelength-dependent albedo can be inferred from the exoplanet's reflected light of the host star, but this is not a trivial task. In fact, the planetary signal may be several orders of magnitude lower ($10^{-4}$ or below) than the flux of the host star, thus making its extraction very challenging. Successful detection of the planetary signature of 51~Peg\,b has been recently obtained by using cross-correlation function (CCF) or autocorrelation function (ACF) techniques. In this paper we present an alternative method based on the use of Independent Component Analysis (ICA). In comparison to the above-mentioned techniques, the main advantages of ICA are that the extraction is \textit{"blind"} i.e. it does not require any \textit{a priori} knowledge of the underlying signals, and that our method allows us not only to detect the planet signal but also to estimate its wavelength dependence. To show and quantify the effectiveness of our method we successfully applied it to both simulated data and real data of an eclipsing binary star system. Eventually, when applied to real 51~Peg~+~51~Peg\,b data, our method extracts the signal of 51~Peg but we could not soundly detect the reflected spectrum of 51~Peg\,b mainly due to the insufficient $SNR$ of the input composite spectra. Nevertheless, our results show that with "ad-hoc" scheduled observations an ICA approach will be, in perspective, a very valid tool for studying exoplanetary atmospheres.Comment: 25 pages, 12 figures. Accepted to A

Comparative ontogenetic and transcriptomic analyses shed light on color pattern divergence in cichlid fishes

Funding Information: This study was supported by the Baden-Württemberg Foundation (to Claudius F. Kratochwil), grants by the Deutsche Forschungsgemeinschaft (DFG) to Axel Meyer, Claudius F. Kratochwil (KR 4670/2-1 and KR 4670/4-1), and Paolo Franchini (FR 3399/1-1), and a stipend from the China Scholarship Council (CSC, to Yipeng Liang). We thank Max Grauvogl who conducted the qPCR experiments during his bachelor thesis. Open Access funding enabled and organized by Projekt DEAL. Funding Information: This study was supported by the Baden‐Württemberg Foundation (to Claudius F. Kratochwil), grants by the Deutsche Forschungsgemeinschaft (DFG) to Axel Meyer, Claudius F. Kratochwil (KR 4670/2‐1 and KR 4670/4‐1), and Paolo Franchini (FR 3399/1‐1), and a stipend from the China Scholarship Council (CSC, to Yipeng Liang). We thank Max Grauvogl who conducted the qPCR experiments during his bachelor thesis. Open Access funding enabled and organized by Projekt DEAL. Publisher Copyright: © 2022 The Authors. Evolution & Development published by Wiley Periodicals LLC.Stripe patterns are a striking example for a repeatedly evolved color pattern. In the African adaptive radiations of cichlid fishes, stripes evolved several times independently. Previously, it has been suggested that regulatory evolution of a single gene, agouti-related-peptide 2 (agrp2), explains the evolutionary lability of this trait. Here, using a comparative transcriptomic approach, we performed comparisons between (adult) striped and nonstriped cichlid fishes of representatives of Lake Victoria and the two major clades of Lake Malawi (mbuna and non-mbuna lineage). We identify agrp2 to be differentially expressed across all pairwise comparisons, reaffirming its association with stripe pattern divergence. We therefore also provide evidence that agrp2 is associated with the loss of the nonstereotypic oblique stripe of Mylochromis mola. Complementary ontogenetic data give insights into the development of stripe patterns as well as vertical bar patterns that both develop postembryonically. Lastly, using the Lake Victoria species pair Haplochromis sauvagei and Pundamilia nyererei, we investigated the differences between melanic and non-melanic regions to identify additional genes that contribute to the formation of stripes. Expression differences—that most importantly also do not include agrp2—are surprisingly small. This suggests, at least in this species pair, that the stripe phenotype might be caused by a combination of more subtle transcriptomic differences or cellular changes without transcriptional correlates. In summary, our comprehensive analysis highlights the ontogenetic and adult transcriptomic differences between cichlids with different color patterns and serves as a basis for further investigation of the mechanistic underpinnings of their diversification.Peer reviewe

Antitumor bioactivity and gut microbiota modulation of polyhydroxybutyrate (PHB) in a rat animal model for colorectal cancer

Polyhydroxybutyrate (PHB) is a non-toxic polyhydroxyalkanoate polymer produced by several microorganisms, widely used as a biological substitute for plastics derived from fossil hydrocarbons. In this work, PHB polymer has been tested in an animal model for colorectal cancer. In the animal model, PHB has been able to reduce the number of polyps by 48,1%, and the tumoral extension area by 58,1%. Also, PHB induces a selective increase in beneficial gut bacterial taxons in this animal model, and a selective reduction in pro-inflammatory taxons, demonstrating its value as a nutraceutical compound. This antitumor effect is caused by gut production of 3hydroxybutyrate and butyrate. In this animal model, 3-hydroxybutyrate is also observed in plasma and in brain tissue, after PHB consumption, making PHB supplementation interesting as a bioactive compound in other extraintestinal conditions, as 3-hydroxybutyrate has been reported to enhance brain and cognitive function, cardiac performance, appetite suppression and diabetes. Therefore, PHB could be postulated as an interesting non-polysaccharide antitumor prebiotic, paving the way towards its future use in functional foods

Understanding Vehicle-to-Vehicle IEEE 802.11p Beaconing Performance in Real-World Highway Scenarios

Periodic exchange of situational information (beacons) is at the basis of most active safety applications in vehicular environments. Despite its fundamental role in raising the level of "situational awareness" onboard vehicles, very little is known to date on beaconing performance in a real vehicular environment. This paper analyzes the results of two measurement campaigns that have been designed with the purpose of disclosing beaconing performance in a variety of vehicular links, for what concerns vehicle configuration (tall/short), line-of-sight conditions (LOS/NLOS), as well as single-hop or two-hop propagation of the information reported in the beacons. For the first time, beaconing performance is characterized in terms of not only the packet (beacon) delivery rate (PDR), but also in terms of the packet (beacon) inter-reception (PIR) time. The latter metric has been suggested in the literature as more accurately measuring the level of "situation awareness" onboard vehicles than the traditional PDR metric. This paper also presents a simulation-based analysis aimed at estimating the benefit of multi-hop propagation of situational information beyond the second hop of communication. The analysis of the data collected in the measurement campaigns as well as the simulation-based analysis disclose a number of interesting insights which might prove useful in the design of active safety applications. Finally, another major contribution of this paper is promoting the Gilbert-Elliot model, previously proposed to model bit-error bursts in packet switched networks, as a very accurate model of beacon reception behavior observed in real-world scenarios