494 research outputs found
Stochastic nonlinear differential equation generating 1/f noise
Starting from the simple point process model of 1/f noise we derive a
stochastic nonlinear differential equation for the signal exhibiting 1/f noise
in any desirably wide range of frequency. A stochastic differential equation
(the general Langevin equation with a multiplicative noise) that gives 1/f
noise is derived for the first time. The solution of the equation exhibits the
power-law distribution. The process with 1/f noise is demonstrated by the
numerical solution of the derived equation with the appropriate restriction of
the diffusion of the signal in some finite interval.Comment: 3 figure
Electrodynamics of Moving Media
Contains reports on two research projects.Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DA 36-039-AMC-03200(E
Electrical and Noise Characteristics of Graphene Field-Effect Transistors: Ambient Effects and Noise Sources
We fabricated a large number of single and bilayer graphene transistors and
carried out a systematic experimental study of their low-frequency noise
characteristics. A special attention was given to determining the dominant
noise sources in these devices and the effect of aging on the current-voltage
and noise characteristics. The analysis of the noise spectral density
dependence on the area of graphene channel showed that the dominant
contributions to the low-frequency electronic noise come from the graphene
layer itself rather than from the contacts. Aging of graphene transistors due
to exposure to ambient for over a month resulted in substantially increased
noise attributed to the decreasing mobility of graphene and increasing contact
resistance. The noise spectral density in both single and bilayer graphene
transistors either increased with deviation from the charge neutrality point or
depended weakly on the gate bias. This observation confirms that the
low-frequency noise characteristics of graphene transistors are qualitatively
different from those of conventional silicon metal-oxide-semiconductor
field-effect transistors.Comment: 26 pages with 8 figure
The Life of a Professor: Stress and Coping
The life of a professor is a balancing act, both professionally and personally. Professors must weigh the demands of research, publishing, teaching, and service with the requirements of their personal responsibilities. The purpose of this mixed-methods study was to explore the role of stress on the work-life balance of a professor. This study was conducted by an interdisciplinary research team and included participants from a wide-range of academic fields. A mixed-methods approach, utilizing an electronic survey composed of demographic questions, Likert-scale responses, and open-ended questions, yielded data related to the benefits and challenges of being a professor from 31 states in the United States as well as from other countries. Structured interviews were then conducted to reveal the coping methods of the participants. In addition, this article incorporated embedded media in the form of audio sound bites and animated video, which provided the ‘voice’ of the faculty. The triangulated data revealed that lack of supports, both social and institutional, significantly increased the stress experienced by professors. Mechanisms for coping with stress that could be utilized by individual professors as well as institutional stress management strategies were discussed
Diversity, competition, extinction: the ecophysics of language change
As early indicated by Charles Darwin, languages behave and change very much
like living species. They display high diversity, differentiate in space and
time, emerge and disappear. A large body of literature has explored the role of
information exchanges and communicative constraints in groups of agents under
selective scenarios. These models have been very helpful in providing a
rationale on how complex forms of communication emerge under evolutionary
pressures. However, other patterns of large-scale organization can be described
using mathematical methods ignoring communicative traits. These approaches
consider shorter time scales and have been developed by exploiting both
theoretical ecology and statistical physics methods. The models are reviewed
here and include extinction, invasion, origination, spatial organization,
coexistence and diversity as key concepts and are very simple in their defining
rules. Such simplicity is used in order to catch the most fundamental laws of
organization and those universal ingredients responsible for qualitative
traits. The similarities between observed and predicted patterns indicate that
an ecological theory of language is emerging, supporting (on a quantitative
basis) its ecological nature, although key differences are also present. Here
we critically review some recent advances lying and outline their implications
and limitations as well as open problems for future research.Comment: 17 Pages. A review on current models from statistical Physics and
Theoretical Ecology applied to study language dynamic
- …