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

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

CLOTHING DECONTAMINATION AND EVALUATION OF LAUNDRY METHODS

The over-all objectives of this project encompassed testing the suitability of standard and special laundering methods and standard equipment for field decontamination of clothing; evaluating the contaminability and decontaminability of selected fabrics, and testing of experimental clothing monitoring instruments. Garments and fabrics contaminated by controlled methods were used during the operation for testing the equipment and evaluating fabrics and formulae. 8tandard Army laundering methods and equipment, including wooden washers, were effective for decontaminating clothing in the field. A decontaminating laundry formula employing citric acid and tartaric acid followed by either an organic or inorganic chelating agent results in a higher degree of decontamination than other formulae tested. The standard Quartermaster Corps mobile field laundry formula resulted in satisfactory decontamination with the type of soil and activity encountered and the cost of supplies is approximately one-tenth as much as the special formulae. Woolen garments and fabric swatches were decontanninated by laundering as readily as cotton or synthetic fabrics. Clothing monitoring instruments under development appear suitable for monitoring clothing under field conditions to determine the degree of contamination both before and after precessing. (auth

Component greenhouse gas fluxes and radiative balance from two deltaic marshes in Louisiana: Pairing chamber techniques and eddy covariance

Coastal marshes take up atmospheric CO2 while emitting CO2, CH4, and N2O. This ability to sequester carbon (C) is much greater for wetlands on a per area basis than from most ecosystems, facilitating scientific, political, and economic interest in their value as greenhouse gas sinks. However, the greenhouse gas balance of Gulf of Mexico wetlands is particularly understudied. We describe the net ecosystem exchange (NEEc) of CO2 and CH4 using eddy covariance (EC) in comparison with fluxes of CO2, CH4, and N2O using chambers from brackish and freshwater marshes in Louisiana, USA. From EC, we found that 182 g Cm-2 yr-1 was lost through NEEc from the brackish marsh. Of this, 11 g Cm-2 yr-1 resulted from net CH4 emissions and the remaining 171 g Cm-2 yr-1 resulted from net CO2 emissions. In contrast, -290 g Cm2 yr-1 was taken up through NEEc by the freshwater marsh, with 47 g Cm-2 yr-1 emitted as CH4 and -337 g Cm-2 yr-1 taken up as CO2. From chambers, we discovered that neither site had large fluxes of N2O. Sustained-flux greenhouse gas accounting metrics indicated that both marshes had a positive (warming) radiative balance, with the brackish marsh having a substantially greater warming effect than the freshwater marsh. That net respiratory emissions of CO2 and CH4 as estimated through chamber techniques were 2–4 times different from emissions estimated through EC requires additional understanding of the artifacts created by different spatial and temporal sampling footprints between techniques

Adenocarcinoma arising at ileostomy sites: Two cases and a review of the literature

Total colectomy with ileostomy placement is a treatment for patients with inflammatory bowel disease or familial adenomatous polyposis (FAP). A rare and late complication of this treatment is carcinoma arising at the ileostomy site. We describe two such cases: a 78-year-old male 30 years after subtotal colectomy and ileostomy for FAP, and an 85-year-old male 50 years after colectomy and ileostomy for ulcerative colitis. The long latency period between creation of the ileostomies and development of carcinoma suggests a chronic metaplasia due to an irritating/inflammatory causative factor. Surgical excision of the mass and relocation of the stoma is the mainstay of therapy, with possible benefits from adjuvant chemotherapy. Newly developed lesions at stoma sites should be biopsied to rule out the possibility of this rare ileostomy complication

Evaluation of Technologies to Complement/Replace Mass Spectrometers in the Tritium Facilities

The primary goal of this work is to determine the suitability of the Infraran sensor for use in the Palladium Membrane Reactor. This application presents a challenge for the sensor, since the process temperature exceeds its designed operating range. We have demonstrated that large baseline offsets, comparable to the sensor response to the analyte, are obtained if cool air is blown across the sensor. We have also shown that there is a strong environmental component to the noise. However, the current arrangement does not utilize a reference detector. The strong correlation between the CO and H{sub 2}O sensor responses to environmental changes indicate that a reference detector can greatly reduce the environmental sensitivity. In fact, incorporation of a reference detector is essential for the sensor to work in this application. We have also shown that the two sensor responses are adequately independent. Still, there are several small corrections which must to be made to the sensor response to accommodate chemical and physical effects. Interactions between the two analytes will alter the relationship between number density and pressure. Temperature and pressure broadening will alter the relationship between absorbance and number density. The individual effects are small--on the order of a few percent or less--but cumulatively significant. Still, corrections may be made if temperature and total pressure are independently measured and incorporated into a post-analysis routine. Such corrections are easily programmed and automated and do not represent a significant burden for installation. The measurements and simulations described above indicate that with appropriate corrections, the Infraran sensor can approach the 1-1.5% measurement accuracy required for effective PMR process control. It is also worth noting that the Infraran may be suitable for other gas sensing applications, especially those that do not need to be made in a high-temperature environment. Any gas with an infrared absorption (methane, ammonia, etc.) may be detected so long as an appropriate bandpass filter can be manufactured. Note that homonuclear diatomic molecules (hydrogen and its isotopes, nitrogen, oxygen) do not have infrared absorptions. We have shown that the sensor response may be adequately predicted using commercially available software. Measurement of trace concentrations is limited by the broad spectral bandpass, since the total signal includes non-absorbed frequencies. However, cells with longer pathlengths can be designed to address this problem

The Depth and Dynamics of Context: Tracing the Sources and Channels of Engagement and Disengagement in Students' Response to Literature

In this article, we analyze one coauthor's 12th-grade English class, focusing on a small group of students who interpreted the character of Gertrude in Hamlet through a body biography, a life-sized human outline that students filled with words and images that represented their understanding of the character. We analyze the body biography production as a function of the social context of activity and then analyze the processes of composition involved in their production. Analysis of the data reveals that (a) the students exhibited different degrees of commitment to and involvement in the group task, (b) the degree of equity in productivity and social relations varied within the group in accordance with these different degrees of engagement, and (c) the inequity in social relations and contributions to the group product belied the degree to which the final interpretive product met the teacher's assessment criteria. We conclude with a reconsideration of the notion of engagement that includes attention to both the immediate social relations within the classroom and the histories of engagement that students bring to class.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline

Point process model of 1/f noise versus a sum of Lorentzians

We present a simple point process model of $1/f^{\beta}$ noise, covering different values of the exponent $\beta$. The signal of the model consists of pulses or events. The interpulse, interevent, interarrival, recurrence or waiting times of the signal are described by the general Langevin equation with the multiplicative noise and stochastically diffuse in some interval resulting in the power-law distribution. Our model is free from the requirement of a wide distribution of relaxation times and from the power-law forms of the pulses. It contains only one relaxation rate and yields $1/f^ {\beta}$ spectra in a wide range of frequency. We obtain explicit expressions for the power spectra and present numerical illustrations of the model. Further we analyze the relation of the point process model of $1/f$ noise with the Bernamont-Surdin-McWhorter model, representing the signals as a sum of the uncorrelated components. We show that the point process model is complementary to the model based on the sum of signals with a wide-range distribution of the relaxation times. In contrast to the Gaussian distribution of the signal intensity of the sum of the uncorrelated components, the point process exhibits asymptotically a power-law distribution of the signal intensity. The developed multiplicative point process model of $1/f^{\beta}$ noise may be used for modeling and analysis of stochastic processes in different systems with the power-law distribution of the intensity of pulsing signals.Comment: 23 pages, 10 figures, to be published in Phys. Rev.

Universal 1/f Noise from Dissipative SOC Models

We introduce a model able to reproduce the main features of 1/f noise: hyper-universality (the power-law exponents are independent on the dimension of the system; we show here results in d=1,2) and apparent lack of a low-frequency cutoff in the power spectrum. Essential ingredients of this model are an activation-deactivation process and dissipation.Comment: 3 Latex pages, 2 eps Figure