15,830 research outputs found
Near-Optimal Evasion of Convex-Inducing Classifiers
Classifiers are often used to detect miscreant activities. We study how an
adversary can efficiently query a classifier to elicit information that allows
the adversary to evade detection at near-minimal cost. We generalize results of
Lowd and Meek (2005) to convex-inducing classifiers. We present algorithms that
construct undetected instances of near-minimal cost using only polynomially
many queries in the dimension of the space and without reverse engineering the
decision boundary.Comment: 8 pages; to appear at AISTATS'201
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No Abstract.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/50352/1/410320425_ftp.pd
Toward Equations of Galactic Structure
We find that all classes of galaxies, ranging from disks to spheroids and
from dwarf spheroidals to brightest cluster galaxies, lie on a two dimensional
surface within the space defined by the logarithms of the half-light radius,
r_e, mean surface brightness within r_e, I_e, and internal velocity, V^2 =
(1/2)v_c^2 + sigma^2, where v_c is the rotational velocity and sigma is the
velocity dispersion. If these quantities are expressed in terms of kpc,
L_solar/pc^2, and km/s, then log r_e - log V^2 + log I_e + log Upsilon_e + 0.8
= 0, where we provide a fitting function for Upsilon_e, the mass-to-light ratio
within r_e in units of M_solar/L_solar, that depends only on V and I_e. The
scatter about this surface for our heterogeneous sample of 1925 galaxies is
small (< 0.1 dex) and could be as low as ~ 0.05 dex, or 10%. This small scatter
has three possible implications for how gross galactic structure is affected by
internal factors, such as stellar orbital structure, and by external factors,
such as environment. These factors either 1) play no role beyond generating
some of the observed scatter, 2) move galaxies along the surface, or 3) balance
each other to maintain this surface as the locus of galactic structure
equilibria. We cast the behavior of Upsilon_e in terms of the fraction of
baryons converted to stars, eta, and the concentration of those stars within
the dark matter halo, xi = R_{200}/r_e. We derive eta = 1.9 x 10^{-5} (L/L^*)
Upsilon_* V^{-3} and xi = 1.4 V/r_e. Finally, we present and discuss the
distributions of eta and xi for the full range of galaxies. For systems with
internal velocities comparable to that of the Milky Way (149 < V < 163 km/s),
eta = 0.14 +- 0.05, and xi is, on average, ~ 5 times greater for spheroids than
for disks. (Abridged)Comment: submitted to Ap
Predicting occupational strain and job satisfaction: the role of stress, coping, personality, and affectivity variables
Four studies employed path analysis to examine how measures of occupational stressors, coping resources, and negative affectivity (NA) and positive affectivity (PA) interact to predict occupational strain. The Occupational Stress Inventory (Osipow & Spokane, 1987) was used to measure stress, strain, and coping. The Positive and Negative Affectivity Schedule (Watson, Clark, & Tellegen, 1988) was
used for the affectivity variables. The hypothesised model showed NA and PA as background dispositional variables that influenced relations among stress, strain, and coping while still allowing stress and coping to have a direct influence on strain. Goodness of fit indices were acceptable with the model predicting 15 per cent of the variance in stress, 24 per cent of coping, and 70 per cent of strain. Study 2 replicated these findings. Study 3 added a positive outcome variable, job satisfaction (JSI: Brayfield & Rothe, 1951) to the model. The expanded model again fit the data well. A fourth study added a global measure of personality (NEO-FFI: Costa & McCrae, 1991) to the model tested in Study 3. Results indicated that personality measures did not add
anything to the prediction of job satisfaction and strain in a model that already included measures of stressors, coping resources, NA and PA. The series of four studies yielded a reliable structural model that highlights the influence of organizational and dispositional variables on occupational strain and job satisfaction
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Genomes, expression profiles, and diversity of mitochondria of the White-footed Deermouse Peromyscus leucopus, reservoir of Lyme disease and other zoonoses.
The cricetine rodents Peromyscus leucopus and P. maniculatus are key reservoirs for several zoonotic diseases in North America. We determined the complete circular mitochondrial genome sequences of representatives of 3 different stock colonies of P. leucopus, one stock colony of P. maniculatus and two wild populations of P. leucopus. The genomes were syntenic with that of the murids Mus musculus and Rattus norvegicus. Phylogenetic analysis confirmed that these two Peromyscus species are sister taxa in a clade with P. polionotus and also uncovered a distinction between P. leucopus populations in the eastern and the central United States. In one P. leucopus lineage four extended regions of mitochondrial pseudogenes were identified in the nuclear genome. RNA-seq analysis revealed transcription of the entire genome and differences from controls in the expression profiles of mitochondrial genes in the blood, but not in liver or brain, of animals infected with the zoonotic pathogen Borrelia hermsii. PCR and sequencing of the D-loop of the mitochondrion identified 32 different haplotypes among 118 wild P. leucopus at a Connecticut field site. These findings help to further establish P. leucopus as a model organism for studies of emerging infectious diseases, ecology, and in other disciplines
A numerical adaptation of SAW identities from the honeycomb to other 2D lattices
Recently, Duminil-Copin and Smirnov proved a long-standing conjecture by
Nienhuis that the connective constant of self-avoiding walks on the honeycomb
lattice is A key identity used in that proof depends on
the existence of a parafermionic observable for self-avoiding walks on the
honeycomb lattice. Despite the absence of a corresponding observable for SAW on
the square and triangular lattices, we show that in the limit of large
lattices, some of the consequences observed on the honeycomb lattice persist on
other lattices. This permits the accurate estimation, though not an exact
evaluation, of certain critical amplitudes, as well as critical points, for
these lattices. For the honeycomb lattice an exact amplitude for loops is
proved.Comment: 21 pages, 7 figures. Changes in v2: Improved numerical analysis,
giving greater precision. Explanation of why we observe what we do. Extra
reference
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