Due to its anti-jamming capability, chirp spread spectrum (CSS) technique has attracted much attention in the area of wireless communications. However, there has been little rigorous analysis for the anti-jamming performance of CSS-based communication systems. In this paper, we present analytic results on the anti-jamming performance of a CSS-based system: BER expressions are derived for a CSS-...

background : the education of preventing hiv/aids among the students 1s one of the best methods to prevent the spread of aids virus. the awareness of the students' knowledge about this disease is the first step in this way. methods : this descriptive-analytic study (cross-sectional) was done in hamadan male high schools in 1383-84, by using a closed questionnaire, the data was collected from 40...

A simple model of near-field pixel-to-pixel image transfer using magneto-inductive arrays is presented. The response of Ndimensional rectangular arrays is first found as an excitation of eigenmodes. This analytical method involves approximating the effect of sources and detectors, and replaces the problem of solving large numbers of simultaneous equations with that of evaluating a sum. Expressi...

A complex contagion is an infectious process in which an individual may require multiple transmissions. We typically think of individuals as beginning inactive and becoming active once they are contacted by sufficient numbers of active partners. These have been studied in a number of contexts, but the analytic models for dynamic spread of complex contagions are typically complex. Here we study ...

Image analysis in the presence of surface scatter due to residual optical fabrication errors is often perceived to be complicated, nonintuitive, and achieved only by computationally intensive nonsequential ray tracing with commercial optical analysis codes such as ASAP, Zemax, Code V, TracePro, or FRED. However, we show that surface scatter can be treated very similarly to conventional wavefron...

A specific form of the Mellin transform, referred to as the “scale transform,” is known to be a natural complement to the Fourier transform for wideband analytic signals. In this paper, limitations for the simultaneous localization of scale transform pairs are investigated. A number of inequalities are established and discussed, based on various measures of spread (Heisenberg-type inequalities ...

The existence of sexual partnerships that overlap in time (concurrent relationships) is believed by some to be a significant contributing factor to the spread of HIV, although this is controversial. We derive an analytic model which allows us to investigate and compare disease spread in populations with and without concurrency. We can identify regions of parameter space in which its impact is n...

The spread of crime is a complex, dynamic process that calls for a systems level approach. Here, we build and analyze a series of dynamical systems models of the spread of crime, imprisonment and recidivism, using only abstract transition parameters. To find the general patterns among these parameters--patterns that are independent of the underlying particulars--we compute analytic expressions ...

We postulate that the nature of information items plays a vital role in the observed spread of these items in a social network. We capture this intuition by proposing a model that assigns to every information item two parameters: endogeneity and exogeneity. The endogeneity of the item quantifies its tendency to spread primarily through the connections between nodes; the exogeneity quantifies it...