10,717 research outputs found
Characteristic Length Scale of Electric Transport Properties of Genomes
A tight-binding model together with a novel statistical method are used to
investigate the relation between the sequence-dependent electric transport
properties and the sequences of protein-coding regions of complete genomes. A
correlation parameter is defined to analyze the relation. For some
particular propagation length , the transport behaviors of the coding
and non-coding sequences are very different and the correlation reaches its
maximal value . and \omax are characteristic values for
each species. The possible reason of the difference between the features of
transport properties in the coding and non-coding regions is the mechanism of
DNA damage repair processes together with the natural selection.Comment: 4 pages, 4 figure
Understanding Rates of Marijuana Use and Consequences Among Adolescents in a Changing Legal Landscape.
Purpose of Review:There is not one answer to address whether marijuana use has increased, decreased, or stayed the same given changes in state legalization of medical and non-medical marijuana in the USA. Recent Findings:Evidence suggests some health benefits for medical marijuana; however, initiation of marijuana use is a risk factor for developing problem cannabis use. Though use rates have remained stable over recent years, about one in three 10th graders report marijuana use, most adolescents do not view the drug as harmful, and over 650,000 youth aged 12 to 17 struggle with cannabis use disorder. Summary:Although the health benefits of medical marijuana are becoming better understood, more research is needed. Intervention and prevention programs must better address effects of marijuana, acknowledging that while there may be some benefits medically, marijuana use can affect functioning during adolescence when the brain is still developing
The Unpredictability of the Most Energetic Solar Events
Observations over the past two solar cycles show a highly irregular pattern
of occurrence for major solar flares, gamma-ray events, and solar energetic
particle (SEP) fluences. Such phenomena do not appear to follow the direct
indices of solar magnetic activity, such as the sunspot number. I show that
this results from the non-Poisson occurrence for the most energetic events.
This Letter also points out a particularly striking example of this
irregularity in a comparison between the declining phases of the recent two
solar cycles (1993-1995 and 2004-2006, respectively) and traces it through the
radiated energies of the flares, the associated SEP fluences, and the sunspot
areas. These factors suggest that processes in the solar interior involved with
the supply of magnetic flux up to the surface of the Sun have strong
correlations in space and time, leading to a complex occurrence pattern that is
presently unpredictable on timescales longer than active region lifetimes
(weeks) and not correlated well with the solar cycle itself.Comment: 4 page
Learning Temporal Transformations From Time-Lapse Videos
Based on life-long observations of physical, chemical, and biologic phenomena
in the natural world, humans can often easily picture in their minds what an
object will look like in the future. But, what about computers? In this paper,
we learn computational models of object transformations from time-lapse videos.
In particular, we explore the use of generative models to create depictions of
objects at future times. These models explore several different prediction
tasks: generating a future state given a single depiction of an object,
generating a future state given two depictions of an object at different times,
and generating future states recursively in a recurrent framework. We provide
both qualitative and quantitative evaluations of the generated results, and
also conduct a human evaluation to compare variations of our models.Comment: ECCV201
Kinetic Inductance of Josephson Junction Arrays: Dynamic and Equilibrium Calculations
We show analytically that the inverse kinetic inductance of an
overdamped junction array at low frequencies is proportional to the admittance
of an inhomogeneous equivalent impedance network. The bond in this
equivalent network has an inverse inductance
, where is the Josephson
coupling energy of the bond, is the ground-state phase
of the grain , and is the usual magnetic phase factor. We use this
theorem to calculate for square arrays as large as .
The calculated is in very good agreement with the low-temperature
limit of the helicity modulus calculated by conventional equilibrium
Monte Carlo techniques. However, the finite temperature structure of ,
as a function of magnetic field, is \underline{sharper} than the
zero-temperature , which shows surprisingly weak structure. In
triangular arrays, the equilibrium calculation of yields a series of
peaks at frustrations , where is an integer , consistent with experiment.Comment: 14 pages + 6 postscript figures, 3.0 REVTe
The investigation of STEM Self-Efficacy and Professional Commitment to Engineering among female high school students
This study employed social cognitive theory and social cognitive career theory (SCCT) as foundations to explore the influence of high school students’ beliefs about female gender roles and female engineer role models on science, technology, engineering, and mathematics (STEM)self-efficacy and professional commitment to engineering. A total of 88 students from a national girls’ high school participated in STEM project-based learning. A survey questionnaire named The STEM Self-efficacy and Professional Commitment to Engineering Questionnaire, developed by the researchers, was administered to collect data, and a structured equation model was employed to confirm the multi-theoretical model developed in this study. The results of this study show that enhancing the gender role beliefs and engineer role models of female students may increase their STEM self-efficacy and professional commitment to engineering. In other words, the female high school students’ professional commitment to engineering model can explain students’ intentions for future engineering careers. Thus, this study suggests integrating STEM project-based learning into the curricula of various schools and integrating female engineer role models into STEM project-based learning activities for female students, which can enhance female high school students’ STEM self-efficacy and professional commitment to engineering.Keywords: female engineer role model; female gender role beliefs; professional commitment to engineering; STEM project-based learning; STEM self-efficac
Fast divide-and-conquer algorithms for preemptive scheduling problems with controllable processing times – A polymatroid optimization approach
We consider a variety of preemptive scheduling problems with controllable processing times on a single machine and on identical/uniform parallel machines, where the objective
is to minimize the total compression cost. In this paper, we propose fast divide-and-conquer algorithms for these scheduling problems. Our approach is based on the observation that each scheduling problem we discuss can be formulated as a polymatroid optimization problem.
We develop a novel divide-and-conquer technique for the polymatroid optimization problem and then apply it to each scheduling problem. We show that each scheduling problem can
be solved in O(Tfeas(n) log n) time by using our divide-and-conquer technique, where n is the number of jobs and Tfeas(n) denotes the time complexity of the corresponding feasible scheduling problem with n jobs. This approach yields faster algorithms for most of the scheduling problems discussed in this paper
Perturbative tests of non-perturbative counting
We observe that a class of quarter-BPS dyons in N=4 theories with charge
vector (Q, P) and with nontrivial values of the arithmetic duality invariant I
:= gcd (Q wedge P) are nonperturbative in one frame but perturbative in another
frame. This observation suggests a test of the recently computed
nonperturbative partition functions for dyons with nontrivial values of the
arithmetic invariant. For all values of I, we show that the nonperturbative
counting yields vanishing indexed degeneracy for this class of states
everywhere in the moduli space in precise agreement with the perturbative
result.Comment: 10 pages, 0 figure
Evaluation of Boundary Conditions for the Gust-Cascade Problem
Using a high-order accuracy finite-difference time-domain algorithm, the acoustic scattering from a flat-plate cascade is computed. Keeping the grid and time step fixed, the effect of four different boundary conditions on the accuracy and stability of the computed solution is compared
Structure Space of Model Proteins --A Principle Component Analysis
We study the space of all compact structures on a two-dimensional square
lattice of size . Each structure is mapped onto a vector in
-dimensions according to a hydrophobic model. Previous work has shown that
the designabilities of structures are closely related to the distribution of
the structure vectors in the -dimensional space, with highly designable
structures predominantly found in low density regions. We use principal
component analysis to probe and characterize the distribution of structure
vectors, and find a non-uniform density with a single peak. Interestingly, the
principal axes of this peak are almost aligned with Fourier eigenvectors, and
the corresponding Fourier eigenvalues go to zero continuously at the
wave-number for alternating patterns (). These observations provide a
stepping stone for an analytic description of the distribution of structural
points, and open the possibility of estimating designabilities of realistic
structures by simply Fourier transforming the hydrophobicities of the
corresponding sequences.Comment: 14 pages, 12 figures, Conclusion has been modifie
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