Antitrust merger review costs and acquirer lobbying

Documenting the US antitrust review process for M&As in rich detail, we unveil that regulatory costs and risks are significant and that mitigating these risks via lobbying by acquirers may benefit shareholders. Our results show that an adverse antitrust review outcome leads to a decline of 2.8 percent in acquirer firm value. Further, we show that lobbying before deal announcements is associated with more favorable review outcomes. Finally, higher pre-announcement lobbying is valued by shareholders, especially in horizontal deals and deals with a larger expected change in market concentration, which have higher antitrust concerns. However, this positive value effect of lobbying applies only in firms with strong corporate governance. Our results highlight the role of political connections and lobbying for corporate investments when facing regulatory costs and risks

Diversity, drivers and dispersal of East Antarctic soil microbiota

Microbes are the life support system of the biosphere. Their metabolic activities have been tightly linked to establishing and maintaining core ecosystem processes around the globe, including the polar deserts of terrestrial Antarctica. Shaped by the continent’s extreme abiotic constraints and physical isolation, core ecosystem processes such as primary production and geochemical cycling often involve unique taxa with novel functional traits thus emphasizing the high conservational value of endemic microbiota. Up till now, microorganisms were rarely considered in Antarctic conservation frameworks despite growing concerns about complex environmental change and our anthropogenic footprint. Major gaps in biodiversity surveys and a general lack of understanding in the basic ecological concepts (niche and neutral) underlying the assemblage of Antarctic soil microbial communities has led to their poor protection status and regional sampling bias. Systematic retrieval of baseline data across the continent is therefore much needed, especially in Eastern Antarctica. In support of bridging this gap, we combined a comprehensive amplicon survey (>700 soil samples) with multivariate analyses and high-end modelling approaches to discern biogeographic patterns of polar soil bacteria, micro-eukarya and archaea throughout two coastal regions in Eastern Antarctica – the Windmill Islands and hyperarid Vestfold Hills. This thesis entails three simple but important mission statements: (1) to unveil the diversity of East Antarctic soil microbiota using a multi-domain approach; (2) to identify key edaphic drivers and threshold tipping points by advancing methods for quantifying multispecies responses to change along environmental gradients; and (3) to explore the influence of wind-driven dispersal as a new initiative for monitoring ecosystem change using a combination of dust samples and particulate trajectory modelling with historical climate data. Soil biodiversity profiles and co-occurrence networks found bacteria, micro-eukarya and archaea likely to be jointly responsible for molding the microbial backbone of Antarctic polar desert ecosystems. Species co-existence is proposed to be linked to tradeoffs between niche (environmental filtering and competition) and neutral (dispersal, speciation and drift) processes. However, the scales weighing these processes are heavily tipped in favor of strong niche-partitioning, which is expected given the harsh abiotic constraints. Bacteria (average Chao1 = 1427.57), the most strongly niche-driven (wPLN = 1.000, wNB = <0.001), were found to be inherently more diverse than micro-eukarya (average Chao1 = 92.93) and archaea (average Chao1 = 45.60) in the same environments where they co-occurred. In comparison, neutrality played a larger role in the assemblage of micro-eukaryotic (wPLN = <0.001, wNB = 1.000) and archaeal (wPLN = 0.960, wNB = 0.040) communities – especially at the Vestfold Hills, which were identified as a potentially sensitive sink location for local windblown particles travelling westward from the Windmill Islands. Employment of a modified Gradient Forest model enabled us to explore non-linear relationships between biodiversity (>17, 000 sequence variants) and the environment (79 physiochemical variables), for the first time, on the hyperarid Vestfold Hills soil microbiome. Moisture availability was primarily responsible for shaping the regional microbiome. Highest rates of compositional turnover were observed for rarer lineages of bacteria and micro-eukarya within the 10 – 12 % moisture range. Often the most responsive were taxa with phototrophic or nutrient-cycling capacities such as Cyanobacteria, Chlorophyta and Ochrophyta, which were detected in relatively high amounts within soil at Old Wallow (OW) and Rookery Lake (RL). High dispersal propensity of Chlorophyta (>75 %), based on dust biodiversity profiles (n = 25), generated some insight on the potential implications of wind-driven dispersal upon current ecosystem dynamics as Antarctica warms up. In theory, habitat expansion for micro-algal blooms via aeolian processes may lead to increased phototrophic capacity thereby resulting in potential competition for dominance between primary production strategies across Eastern Antarctica. Cascading events from this hypothetical scenario would be especially pertinent if aeolian deposition occurred within the vicinity of bird and seal colonies, like those found at OW and RL in the Vestfold Hills. When also taking into account the distinctive soil micro-eukaryotic and bacterial components at these two East Antarctic sites, OW and RL were recommended as conservation targets for further sampling and protection. Escalation of consequences from climate change and human activities are major threats to Antarctica’s unique biodiversity. In the coming century, strengthening of links between science and governance will be key towards forming a solid basis for future conservation planning and management across Antarctica. Integration of microbial data has been identified as crucial to this action. This thesis tackles one part of the equation by bringing attention to the vastly understudied coastal regions of Eastern Antarctica. More baseline surveys and research, however, are needed to capture the full scope of biodiversity offered by the Antarctic soil microbiome. This enormous effort would require sustained funding, increased international cooperation and greater year-round access to all regions

Analysis of the disulfide bond arrangement of the HIV envelope protein CON-S gp140 ΔCFI shows variability in the V1 and V2 regions

Disulfide bonding of cysteines is one of the most important protein modifications, and it plays a key role in establishing/maintaining protein structures in biologically active forms. Therefore, the determination of disulfide bond arrangement is one important aspect to understanding the chemical structure of a protein and defining its functional domains. Herein, aiming to understand how the HIV-1 envelope protein’s structure influences its immunogenicity, we used an MS-based approach, liquid chromatography electrospray ionization Fourier transform ion cyclotron resonance (LC/ESI-FTICR) mass spectrometry, to determine the disulfide linkages on an oligomeric form of the group M consensus HIV-1 envelope protein (Env), CON-S gp140 ΔCFI. This protein has marked improvement in its immunogenicity, compared to monomeric gp120 and wild-type forms of gp140 Envs. Our results demonstrate that the disulfide connectivity in the Nterminal region of CON-S gp140 ΔCFI is different from the disulfide bonding previously reported in the monomeric form of gp120 HIV-1 Env. Additionally, heterogeneity of the disulfide bonding was detected in this region. These data suggest that the V1/V2 region does not have a single, conserved disulfide bonding pattern, and that variability could impact immunogenicity of expressed Envs

Application of a rank-based genetic association test to age-at-onset data from the Collaborative Study on the Genetics of Alcoholism study

Association studies of quantitative traits have often relied on methods in which a normal distribution of the trait is assumed. However, quantitative phenotypes from complex human diseases are often censored, highly skewed, or contaminated with outlying values. We recently developed a rank-based association method that takes into account censoring and makes no distributional assumptions about the trait. In this study, we applied our new method to age-at-onset data on ALDX1 and ALDX2. Both traits are highly skewed (skewness > 1.9) and often censored. We performed a whole genome association study of age at onset of the ALDX1 trait using Illumina single-nucleotide polymorphisms. Only slightly more than 5% of markers were significant. However, we identified two regions on chromosomes 14 and 15, which each have at least four significant markers clustering together. These two regions may harbor genes that regulate age at onset of ALDX1 and ALDX2. Future fine mapping of these two regions with densely spaced markers is warranted

Hedgehog signalling in allograft vasculopathy: a new therapeutic target?

Allograft vasculopathy (AV) leads to chronic rejection of organ transplants, but its causes are obscure. New research from the Jane-Wit laboratory showed that Sonic Hedgehog (SHH) signalling from damaged graft endothelium drives vasculopathy by promoting proinflammatory cytokine production and NLRP3-inflammasome activation in alloreactive CD4+PTCH1hiPD-1hiT memory cells, offering new diagnostic and therapeutic strategies

Long-Range PSU(2,2|4) Bethe Ansaetze for Gauge Theory and Strings

We generalize various existing higher-loop Bethe ansaetze for simple sectors of the integrable long-range dynamic spin chain describing planar N=4 Super Yang-Mills Theory to the full psu(2,2|4) symmetry and, asymptotically, to arbitrary loop order. We perform a large number of tests of our conjectured equations, such as internal consistency, comparison to direct three-loop diagonalization and expected thermodynamic behavior. In the special case of the su(1|2) subsector, corresponding to a long-range t-J model, we are able to derive, up to three loops, the S-matrix and the associated nested Bethe ansatz from the gauge theory dilatation operator. We conjecture novel all-order S-matrices for the su(1|2) and su(1,1|2) subsectors, and show that they satisfy the Yang-Baxter equation. Throughout the paper, we muse about the idea that quantum string theory on AdS_5xS^5 is also described by a psu(2,2|4) spin chain. We propose asymptotic all-order Bethe equations for this putative "string chain", which differ in a systematic fashion from the gauge theory equations.Comment: 67 pages, In Honor of Hans Bethe, v2: references added, typos fixed, sign conventions improved, v3: published versio

Quantitative autistic trait measurements index background genetic risk for ASD in Hispanic families

BACKGROUND: Recent studies have indicated that quantitative autistic traits (QATs) of parents reflect inherited liabilities that may index background genetic risk for clinical autism spectrum disorder (ASD) in their offspring. Moreover, preferential mating for QATs has been observed as a potential factor in concentrating autistic liabilities in some families across generations. Heretofore, intergenerational studies of QATs have focused almost exclusively on Caucasian populations—the present study explored these phenomena in a well-characterized Hispanic population. METHODS: The present study examined QAT scores in siblings and parents of 83 Hispanic probands meeting research diagnostic criteria for ASD, and 64 non-ASD controls, using the Social Responsiveness Scale-2 (SRS-2). Ancestry of the probands was characterized by genotype, using information from 541,929 single nucleotide polymorphic markers. RESULTS: In families of Hispanic children with an ASD diagnosis, the pattern of quantitative trait correlations observed between ASD-affected children and their first-degree relatives (ICCs on the order of 0.20), between unaffected first-degree relatives in ASD-affected families (sibling/mother ICC = 0.36; sibling/father ICC = 0.53), and between spouses (mother/father ICC = 0.48) were in keeping with the influence of transmitted background genetic risk and strong preferential mating for variation in quantitative autistic trait burden. Results from analysis of ancestry-informative genetic markers among probands in this sample were consistent with that from other Hispanic populations. CONCLUSIONS: Quantitative autistic traits represent measurable indices of inherited liability to ASD in Hispanic families. The accumulation of autistic traits occurs within generations, between spouses, and across generations, among Hispanic families affected by ASD. The occurrence of preferential mating for QATs—the magnitude of which may vary across cultures—constitutes a mechanism by which background genetic liability for ASD can accumulate in a given family in successive generations