1,013 research outputs found
The Effect of Liquidity on Governance
This paper studies the effect of stock liquidity on blockholders’ choice of governance mechanisms. We focus on hedge funds as they are unconstrained by legal restrictions and business ties, and thus have all governance channels at their disposal. Since the threat of governance, not just actual governance, can discipline managers, we use Section 13 filings to measure governance intent rather than only studying instances of actual governance. We find that liquidity increases the likelihood that a hedge fund acquires a block in a firm. Conditional upon acquiring a stake, liquidity reduces the likelihood that a blockholder governs through voice (intervention) – as evidenced by the greater propensity to file Schedule 13Gs (passive investment) rather than 13Ds (active investment). Liquidity is more likely to lead to a 13G filing if the manager’s wealth is sensitive to the stock price, consistent with governance through exit (trading). A 13G filing leads to positive announcement returns, especially in liquid firms. These two results suggest that liquidity does not dissuade blockholders from governing altogether, but instead encourages them to govern through exit rather than voice. We use decimalization as an exogenous shock to liquidity to identify causal effects.
Mitigating baryonic effects with a theoretical error covariance
One of the primary sources of uncertainties in modeling the cosmic-shear
power spectrum on small scales is the effect of baryonic physics. Accurate
cosmology for Stage-IV surveys requires knowledge of the matter power spectrum
deep in the nonlinear regime at the percent level. Therefore, it is important
to develop reliable mitigation techniques to take into account baryonic
uncertainties if information from small scales is to be considered in the
cosmological analysis. In this work, we develop a new mitigation method for
dealing with baryonic physics for the case of the shear angular power spectrum.
The method is based on an extended covariance matrix that incorporates baryonic
uncertainties informed by hydrodynamical simulations. We use the results from
13 hydrodynamical simulations and the residual errors arising from a fit to a
CDM model using the extended halo model code {\tt HMCode} to account
for baryonic physics. These residual errors are used to model a so-called
theoretical error covariance matrix that is added to the original covariance
matrix. In order to assess the performance of the method, we use the 2D
tomographic shear from four hydrodynamical simulations that have different
extremes of baryonic parameters as mock data and run a likelihood analysis
comparing the residual bias on and of our method and the
HMCode for an LSST-like survey. We use different modelling of the theoretical
error covariance matrix to test the robustness of the method. We show that it
is possible to reduce the bias in the determination of the tested cosmological
parameters at the price of a modest decrease in the precision.Comment: 10 pages, 5 figure
Constraining Baryonic Physics with DES Y1 and Planck data -- Combining Galaxy Clustering, Weak Lensing, and CMB Lensing
We constrain cosmology and baryonic feedback scenarios with a joint analysis
of weak lensing, galaxy clustering, cosmic microwave background (CMB) lensing,
and their cross-correlations (so-called 62) using data from the Dark
Energy Survey (DES) Y1 and the Planck satellite mission. Noteworthy features of
our 62 pipeline are: We extend CMB lensing cross-correlation
measurements to a band surrounding the DES Y1 footprint (a gain in
pairs), and we develop analytic covariance capabilities that account for
different footprints and all cross-terms in the 62 analysis. We also
measure the DES Y1 cosmic shear two-point correlation function (2PCF) down to
, but find that going below does not increase
cosmological information due to shape noise. We model baryonic physics
uncertainties via the amplitude of Principal Components (PCs) derived from a
set of hydro-simulations. Given our statistical uncertainties, varying the
first PC amplitude is sufficient to model small-scale cosmic shear 2PCF.
For DES Y1+Planck 62 we find , comparable to the
52 result of DES Y3+SPT/Planck . Combined with our
most informative cosmology priors -- baryon acoustic oscillation (BAO), big
bang nucleosynthesis (BBN), type Ia supernovae (SNe Ia), and Planck 2018
EE+lowE, we measure . Regarding baryonic physics
constraints, our 62 analysis finds . Combined with the
aforementioned priors, it improves the constraint to . For
comparison, the strongest feedback scenario considered in this paper, the
cosmo-OWLS AGN ( K), corresponds to
.Comment: 24 pages, 13 figures, comments are welcome
Snoopy: Surpassing the Scalability Bottleneck of Oblivious Storage
Existing oblivious storage systems provide strong security by hiding access patterns, but do not scale to sustain high throughput as they rely on a central point of coordination. To overcome this scalability bottleneck, we present Snoopy, an object store that is both oblivious and scalable such that adding more machines increases system throughput. Snoopy contributes techniques tailored to the high-throughput regime to securely distribute and efficiently parallelize every system component without prohibitive coordination costs. These techniques enable Snoopy to scale similarly to a plaintext storage system. Snoopy achieves 13.7x higher throughput than Obladi, a state-of-the-art oblivious storage system. Specifically, Obladi reaches a throughput of 6.7K requests/s for two million 160-byte objects and cannot scale beyond a proxy and server machine. For the same data size, Snoopy uses 18 machines to scale to 92K requests/s with average latency under 500ms
Antibiotic prophylaxis in anterior skull‐base surgery: a survey of the North American Skull Base Society
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/151867/1/alr22396.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151867/2/alr22396_am.pd
CostCO: An automatic cost modeling framework for secure multi-party computation
The last decade has seen an explosion in the number of new secure multi-party computation (MPC) protocols that enable collaborative computation on sensitive data. No single MPC protocol is optimal for all types of computation. As a result, researchers have created hybrid-protocol compilers that translate a program into a hybrid protocol that mixes different MPC protocols. Hybrid-protocol compilers crucially rely on accurate cost models, which are handwritten by the compilers\u27 developers, to choose the correct schedule of protocols.
In this paper, we propose CostCO, the first automatic MPC cost modeling framework. CostCO develops a novel API to interface with a variety of MPC protocols, and leverages domain-specific properties of MPC in order to enable efficient and automatic cost-model generation for a wide range of MPC protocols. CostCO employs a two-phase experiment design to efficiently synthesize cost models of the MPC protocol’s runtime as well as its memory and network usage. We verify CostCO’s modeling accuracy for several full circuits, characterize the engineering effort required to port existing MPC protocols, and demonstrate how hybrid-protocol compilers can leverage CostCO’s cost models
Holographic models for undoped Weyl semimetals
We continue our recently proposed holographic description of single-particle
correlation functions for four-dimensional chiral fermions with Lifshitz
scaling at zero chemical potential, paying particular attention to the
dynamical exponent z = 2. We present new results for the spectral densities and
dispersion relations at non-zero momenta and temperature. In contrast to the
relativistic case with z = 1, we find the existence of a quantum phase
transition from a non-Fermi liquid into a Fermi liquid in which two Fermi
surfaces spontaneously form, even at zero chemical potential. Our findings show
that the boundary system behaves like an undoped Weyl semimetal.Comment: 64 pages, 19 figure
Short-Term Effect of Prebiotics Administration on Stool Characteristics and Serum Cytokines Dynamics in Very Young Children with Acute Diarrhea
We investigated the effect of a mixture of long-chain fructo-oligosaccharides, galacto-oligosaccharides and acidic oligosaccharides on the number and consistency of stools and on immune system biomarkers in 104 supplemented and non-supplemented subjects (aged 9-24 months) with acute diarrhea. Interleukin-1 (IL-1), IL-1RA, IL-6, IL-8, IL-10, TNF-α and sIL-2R cytokine levels were determined. The significant decrease in number of stools and increase in stool consistency in the supplemented group was of little clinical relevance. The only significant change in pro- and anti-inflammatory cytokines was decreased TNF-α levels in the supplemented group. Prebiotic supplementation during acute diarrhea episodes did not influence the clinical course
Discovery of Shiga Toxin-Producing Escherichia coli (STEC)-Specific Bacteriophages From Non-fecal Composts Using Genomic Characterization
Composting is a complex biodegradable process that converts organic materials into nutrients to facilitate crop yields, and, if well managed, can render bactericidal effects. Majority of research focused on detection of enteric pathogens, such as Shiga toxin-producing Escherichia coli (STEC) in fecal composts. Recently, attention has been emphasized on bacteriophages, such as STEC-specific bacteriophages, associated with STEC from the fecal-contaminated environment because they are able to sustain adverse environmental condition during composting process. However, little is known regarding the isolation of STEC-specific bacteriophages in non-fecal composts. Thus, the objectives were to isolate and genomically characterize STEC-specific bacteriophages, and to evaluate its association with STEC in non-fecal composts. For bacteriophage isolation, the samples were enriched with non-pathogenic E. coli (3 strains) and STEC (14 strains), respectively. After purification, host range, plaque size, and phage morphology were examined. Furthermore, bacteriophage genomes were subjected to whole-genome sequencing using Illumina MiSeq and genomic analyses. Isolation of top six non-O157 and O157 STEC utilizing culture methods combined with PCR-based confirmation was also conducted. The results showed that various STEC-specific bacteriophages, including vB_EcoM-Ro111lw, vB_EcoM-Ro121lw, vB_EcoS-Ro145lw, and vB_EcoM-Ro157lw, with different but complementary host ranges were isolated. Genomic analysis showed the genome sizes varied from 42kb to 149kb, and most bacteriophages were unclassified at the genus level, except vB_EcoM-Ro111lw as FelixO1-like viruses. Prokka predicted less than 25% of the ORFs coded for known functions, including those essential for DNA replication, bacteriophage structure, and host cell lysis. Moreover, none of the bacteriophages harbored lysogenic genes or virulence genes, such as stx or eae. Additionally, the presence of these lytic bacteriophages was likely attributed to zero isolation of STEC and could also contribute to additional antimicrobial effects in composts, if the composting process was insufficient. Current findings indicate that various STEC-specific bacteriophages were found in the non-fecal composts. In addition, the genomic characterization provides in-depth information to complement the deficiency of biological features regarding lytic cycle of the new bacteriophages. Most importantly, these bacteriophages have great potential to control various serogroups of STEC
The effect of parental opportunism, IJV's autonomy and tacit knowledge on IJV instability: A comparison of multi-variate regression and fuzzy-set qualitative comparative analysis
This study uses an agency theory perspective to examine how the factors that influence principal (IJV parents) and agent (IJV) relationship may affect IJV instability in China. The study proposes a framework that bridges knowledge-based theory (of tacit knowledge) and agency theory (of parental opportunism) by incorporating reactance theory (of autonomy). By comparing the empirical results of fuzzy-set qualitative comparative analysis (fsQCA) and multiple regression analysis, using a sample of 203 Chinese-foreign IJVs, the study add further evidence to growing methodological consideration regarding complexity theory. The results from multiple regressions show that parental opportunism and IJV’s autonomy has a positive effect on IJV’s instability, and that the interaction of autonomy and tacit knowledge moderates the effect of parental opportunism on IJV instability. However, fsQCA uncovers more causal paths than findings from multiple regression analysis
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