167 research outputs found
Information Disclosure and Security Vulnerability Awareness: A Large-Scale Randomized Field Experiment in Pan-Asia
This paper investigates how the disclosure of a security vulnerability index based on outgoing spams and phishing website hosting which may serve as an indicator of a firm’s inadequate security controls affects companies’ security protection strategy. Our core objective is to study whether firms improve their security when they become aware of their vulnerabilities and such information is publicized. To achieve this goal, we conduct a randomized field experiment on 1,262 firms in six Pan-Asian countries and regions. Among 631 treatment firms, we alert them of their security vulnerability index and ranking over time, and their relative performance compared to their peers via emails and a public advisory website. Compared with control firms without being informed of their security vulnerability index, treatment firms improve their security over time, with a significant reduction of outgoing spam volume. A marginally significant improvement in reducing phishing hosting websites is also observed among non-web hosting treatment firms. The security improvement may be attributed to firms’ proactive reaction to the public security vulnerability information. Our study provides cybersecurity policy makers with useful insights to motivate firms to adopt better security measures
The MOSDEF survey: a stellar mass-SFR-metallicity relation exists at
We investigate the nature of the relation among stellar mass, star-formation
rate, and gas-phase metallicity (the M-SFR-Z relation) at high redshifts
using a sample of 260 star-forming galaxies at from the MOSDEF
survey. We present an analysis of the high-redshift M-SFR-Z relation based
on several emission-line ratios for the first time. We show that a M-SFR-Z
relation clearly exists at . The strength of this relation is similar
to predictions from cosmological hydrodynamical simulations. By performing a
direct comparison of stacks of and galaxies, we find that
galaxies have dex lower metallicity at fixed M and
SFR. In the context of chemical evolution models, this evolution of the
M-SFR-Z relation suggests an increase with redshift of the mass-loading
factor at fixed M, as well as a decrease in the metallicity of infalling
gas that is likely due to a lower importance of gas recycling relative to
accretion from the intergalactic medium at high redshifts. Performing this
analysis simultaneously with multiple metallicity-sensitive line ratios allows
us to rule out the evolution in physical conditions (e.g., N/O ratio,
ionization parameter, and hardness of the ionizing spectrum) at fixed
metallicity as the source of the observed trends with redshift and with SFR at
fixed M at . While this study highlights the promise of
performing high-order tests of chemical evolution models at high redshifts,
detailed quantitative comparisons ultimately await a full understanding of the
evolution of metallicity calibrations with redshift.Comment: 19 pages, 8 figures, accepted to Ap
The MOSDEF Survey: Kinematic and Structural Evolution of Star-Forming Galaxies at
We present ionized gas kinematics for 681 galaxies at from
the MOSFIRE Deep Evolution Field survey, measured using models which account
for random galaxy-slit misalignments together with structural parameters
derived from CANDELS Hubble Space Telescope (HST) imaging. Kinematics and sizes
are used to derive dynamical masses. Baryonic masses are estimated from stellar
masses and inferred gas masses from dust-corrected star formation rates (SFRs)
and the Kennicutt-Schmidt relation. We measure resolved rotation for 105
galaxies. For the remaining 576 galaxies we use models based on HST imaging
structural parameters together with integrated velocity dispersions and
baryonic masses to statistically constrain the median ratio of intrinsic
ordered to disordered motion, . We find that
increases with increasing stellar mass and decreasing specific SFR (sSFR).
These trends may reflect marginal disk stability, where systems with higher gas
fractions have thicker disks. For galaxies with detected rotation we assess
trends between their kinematics and mass, sSFR, and baryon surface density
(). Intrinsic dispersion correlates most with
and velocity correlates most with mass. By comparing
dynamical and baryonic masses, we find that galaxies at are
baryon dominated within their effective radii (), with Mdyn/Mbaryon
increasing over time. The inferred baryon fractions within ,
, decrease over time, even at fixed mass, size, or surface
density. At fixed redshift, does not appear to vary with
stellar mass but increases with decreasing and increasing
. For galaxies at , the median inferred baryon
fractions generally exceed 100%. We discuss possible explanations and future
avenues to resolve this tension.Comment: Accepted to ApJ. Added Figure 9, corrected sample size (main results
unchanged). 28 pages, 13 figure
Bis(morpholin-4-ium) tetrachloridocobalt(II)
The title compound, (C4H10NO)2[CoCl4], is an ionic compound consisting of two protonated tetrahydro-1,4-oxazine (morpholine) cations and a [CoCl4]2− dianion. The CoII ion is in a tetrahedral coordination geometry. The cations exhibit chair-shaped conformations. A three-dimensional supramolecular architecture is formed through N—H⋯Cl and C—H⋯Cl hydrogen bonds between the dianions and the cations
The MOSDEF Survey: An Improved Voronoi Binning Technique on Spatially Resolved Stellar Populations at z~2
We use a sample of 350 star-forming galaxies at from the
MOSFIRE Deep Evolution Field survey to demonstrate an improved Voronoi binning
technique that we use to study the properties of resolved stellar populations
in galaxies. Stellar population and dust maps are constructed from the
high-resolution CANDELS/3D-HST multi-band imaging. Rather than constructing the
layout of resolved elements (i.e., Voronoi bins) from the S/N distribution of
the -band alone, we introduce a modified Voronoi binning method that
additionally incorporates the S/N distribution of several resolved filters. The
SED-derived resolved E(B-V), stellar population ages, SFRs,
and stellar masses that are inferred from the Voronoi bins constructed from
multiple filters are generally consistent with the properties inferred from the
integrated photometry within the uncertainties, with the exception of the
inferred E(B-V) from our sample due to their UV
slopes being unconstrained by the resolved photometry. The results from our
multi-filter Voronoi binning technique are compared to those derived from a
"traditional" single-filter Voronoi binning approach. We find that
single-filter binning produces inferred E(B-V) that are
systematically redder by 0.02 mag on average, but could differ by up to 0.20
mag, and could be attributed to poorly constrained resolved photometry covering
the UV slope. Overall, we advocate that our methodology produces more reliable
SED-derived parameters due to the best-fit resolved SEDs being better
constrained at all resolved wavelengths--particularly those covering the UV
slope.Comment: 23 pages, 15 figures, accepted for publication in MNRA
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