1,334 research outputs found
Stress and Sleep Quality: Mediating Effects of Social Support
Stress is defined as the “nonspecific response of the body to any demand made upon it” (Kohn & Frazer, 1986). Stress is among the top five threats to academic performance among college students (Pettit & DeBarr, 2011). The purpose of the study was to investigate whether stress affects perceived sleep quality, as mediated by social support, and to determine whether stress levels vary based on academic major. Using ANOVA in SPSS 24, we tested three hypotheses: stress and sleep quality are negatively correlated, social support mediates the relationship between stress and sleep quality, and stress levels will vary by academic major (specifically that science, technology, engineering, and mathematics majors will show greater perceived amounts of stress). Results of this study show that there is positive correlation between sleep and stress, a negative correlation between social support and sleep, and a negative correlation between stress and social support
Nonequilibrium phase transition in a model for social influence
We present extensive numerical simulations of the Axelrod's model for social
influence, aimed at understanding the formation of cultural domains. This is a
nonequilibrium model with short range interactions and a remarkably rich
dynamical behavior. We study the phase diagram of the model and uncover a
nonequilibrium phase transition separating an ordered (culturally polarized)
phase from a disordered (culturally fragmented) one. The nature of the phase
transition can be continuous or discontinuous depending on the model
parameters. At the transition, the size of cultural regions is power-law
distributed.Comment: 5 pages, 4 figure
Power Law of Customers' Expenditures in Convenience Stores
In a convenience store chain, a tail of the cumulative density function of
the expenditure of a person during a single shopping trip follows a power law
with an exponent of -2.5. The exponent is independent of the location of the
store, the shopper's age, the day of week, and the time of day.Comment: 9 pages, 5 figures. Accepted for publication in Journal of the
Physical Society of Japan Vol.77No.
“An ethnographic seduction”: how qualitative research and Agent-based models can benefit each other
We provide a general analytical framework for empirically informed agent-based simulations. This methodology provides present-day agent-based models with a sound and proper insight as to the behavior of social agents — an insight that statistical data often fall short of providing at least at a micro level and for hidden and sensitive populations. In the other direction, simulations can provide qualitative researchers in sociology, anthropology and other fields with valuable tools for: (a) testing the consistency and pushing the boundaries, of specific theoretical frameworks; (b) replicating and generalizing results; (c) providing a platform for cross-disciplinary validation of results
How to Choose a Champion
League competition is investigated using random processes and scaling
techniques. In our model, a weak team can upset a strong team with a fixed
probability. Teams play an equal number of head-to-head matches and the team
with the largest number of wins is declared to be the champion. The total
number of games needed for the best team to win the championship with high
certainty, T, grows as the cube of the number of teams, N, i.e., T ~ N^3. This
number can be substantially reduced using preliminary rounds where teams play a
small number of games and subsequently, only the top teams advance to the next
round. When there are k rounds, the total number of games needed for the best
team to emerge as champion, T_k, scales as follows, T_k ~N^(\gamma_k) with
gamma_k=1/[1-(2/3)^(k+1)]. For example, gamma_k=9/5,27/19,81/65 for k=1,2,3.
These results suggest an algorithm for how to infer the best team using a
schedule that is linear in N. We conclude that league format is an ineffective
method of determining the best team, and that sequential elimination from the
bottom up is fair and efficient.Comment: 6 pages, 3 figure
A mutational hot spot in keratin 10 (KRT 10) in patients with epidermolytic hyperkeratosis
Epidermolytic hyperkeratosis (EHK), (bullous congenital ichthyosiform erythroderma), is an autosomal dominant human skin disorder. Recently, we and others have described mutations in keratins 1 and 10 (K1 and K10) in patients with this disease. Structure-function models predict that these mutations would impair normal filament assembly and function. We have extended our earlier studies to include 8 more incidences of EHK. In half of these families, we were unable to locate a mutation within the rod domains of either K1 or K10. However, polymorphic restriction site and sequence analysis of the other families revealed a mutational hot spot within the 1A alpha-helical segment of K10. These involve Arginine to Histidine, Arginine to Cysteine and Arginine to Leucine substitutions at residue 10 of the rod domain. Interestingly, mutations in the corresponding Arginine residue in keratin K14 have been identified in patients with epidermolysis bullosa simplex. The large number of mutations found at this position in both keratins K10 and K14 suggests that other epithelia cell disorders will be discovered that are caused by the corresponding mutation in related type I keratin gene
Quality control and evaluation of plant epigenomics data Comment
Epigenomics is the study of molecular signatures associated with discrete regions within genomes, many of which are important for a wide range of nuclear processes. The ability to profile the epigenomic landscape associated with genes, repetitive regions, transposons, transcription, differential expression, cis-regulatory elements, and 3D chromatin interactions has vastly improved our understanding of plant genomes. However, many epigenomic and single-cell genomic assays are challenging to perform in plants, leading to a wide range of data quality issues; thus, the data require rigorous evaluation prior to downstream analyses and interpretation. In this commentary, we provide considerations for the evaluation of plant epigenomics and single-cell genomics data quality with the aim of improving the quality and utility of studies using those data across diverse plant species
Alternating Spin and Orbital Dimerization in Strong-coupling Two-band Models
We study a one-dimensional Hamiltonian consisting of coupled SU(2) spin and
orbital degrees of freedom. Using the density matrix renormalization group, we
calculate the phase-diagram and the ground state correlation functions for this
model. We find that, in addition to the ferromagnetic and power-law
antiferromagnetic phases for spin and orbital degrees of freedom, this model
has a gapless line extending from the ferromagnetic phase to the Bethe ansatz
solvable SU(4) critical point, and a gapped phase with doubly degenerate ground
states which form alternating spin and orbital singlets. The spin-gap and the
order parameters are evaluated and the relevance to several recently discovered
spin-gap materials is discussed.Comment: 4 pages REVTEX and 4 Postscript figure
Effect of Hund coupling in the one-dimensional SU(4) Hubbard model
The one-dimensional SU(4) Hubbard model perturbed by Hund coupling is
studied, away from half-filling, by means of renormalization group and
bosonization methods. A spectral gap is always present in the spin-orbital
sector irrespective of the magnitude of the Coulomb repulsion. We further
distinguish between two qualitatively different regimes. At small Hund
coupling, we find that the symmetry of the system is dynamically enlarged to
SU(4) at low energy with the result of {\it coherent} spin-orbital excitations.
When the charge sector is not gapped, a superconducting instability is shown to
exist. At large Hund coupling, the symmetry is no longer enlarged to SU(4) and
the excitations in the spin sector become {\it incoherent}. Furthermore, the
superconductivity can be suppressed in favor of the conventional charge density
wave state.Comment: 10 pages, 1 figur
Spinons in a Crossed-Chains Model of a 2D Spin Liquid
Using Random Phase Approximation, we show that a crossed-chains model of a
spin-1/2 Heisenberg spins, with frustrated interchain couplings, has a
non-dimerized spin-liquid ground state in 2D, with deconfined spinons as the
elementary excitations. The results are confirmed by a bosonization study,
which shows that the system is an example of a `sliding Luttinger liquid'. In
an external field, the system develops an incommensurate field-induced long
range order with a finite transition temperature.Comment: 4 pages, 3 figures; added references; scaling analysis, preserving
spin rotational invariance, is extended to finite temperatur
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