Digital processing of satellite imagery application to jungle areas of Peru

The author has identified the following significant results. The use of clustering methods permits the development of relatively fast classification algorithms that could be implemented in an inexpensive computer system with limited amount of memory. Analysis of CCTs using these techniques can provide a great deal of detail permitting the use of the maximum resolution of LANDSAT imagery. Potential cases were detected in which the use of other techniques for classification using a Gaussian approximation for the distribution functions can be used with advantage. For jungle areas, channels 5 and 7 can provide enough information to delineate drainage patterns, swamp and wet areas, and make a reasonable broad classification of forest types

Ermakov Systems with Multiplicative Noise

Using the Euler-Maruyama numerical method, we present calculations of the Ermakov-Lewis invariant and the dynamic, geometric, and total phases for several cases of stochastic parametric oscillators, including the simplest case of the stochastic harmonic oscillator. The results are compared with the corresponding numerical noiseless cases to evaluate the effect of the noise. Besides, the noiseless cases are analytic and their analytic solutions are briefly presented. The Ermakov-Lewis invariant is not affected by the multiplicative noise in the three particular examples presented in this work, whereas there is a shift effect in the case of the phasesComment: 12 pages, 4 figures, 22 reference

Mechanical Properties of an Eco-friendly Concrete with partial replacement of POC and Rubber

Concrete plants consume 10 billion tons of natural aggregates annually from quarries and gravel plants for produce concrete, this demand requires exploiting natural resources from mountains and rivers producing an ecological imbalance. One solution is to use Palm Oil Clinker (POC), which is eliminated in large quantities in the dumps and rivers without taking advantage of its puzolanic, binding and resistance properties as an aggregate in the concrete; another alternative is to apply rubber from abandoned and discarded tires as waste in landfills or burned, without taking advantage of its performance of improvement in concrete, increasing its resistance to impact and fatigue. Unable to find joint POC and rubber information, this research studies its influence replacing 2.5% rubber (grained and crushed) with 10%, 12.5% and 15% POC in the fine aggregate on traditional concrete; results indicate that with 12.5% of POC as the ideal percentage, the compressive strength, tensile strength and flexural strength rise between 2.16 - 9.54%, so the concrete obtained has a cost of less than 4.09% and has 3.65% less CO2 emission

Neutron star glitches have a substantial minimum size

Glitches are sudden spin-up events that punctuate the steady spin down of pulsars and are thought to be due to the presence of a superfluid component within neutron stars. The precise glitch mechanism and its trigger, however, remain unknown. The size of glitches is a key diagnostic for models of the underlying physics. While the largest glitches have long been taken into account by theoretical models, it has always been assumed that the minimum size lay below the detectability limit of the measurements. In this paper we define general glitch detectability limits and use them on 29 years of daily observations of the Crab pulsar, carried out at Jodrell Bank Observatory. We find that all glitches lie well above the detectability limits and by using an automated method to search for small events we are able to uncover the full glitch size distribution, with no biases. Contrary to the prediction of most models, the distribution presents a rapid decrease of the number of glitches below ~0.05 $\mu$Hz. This substantial minimum size indicates that a glitch must involve the motion of at least several billion superfluid vortices and provides an extra observable which can greatly help the identification of the trigger mechanism. Our study also shows that glitches are clearly separated from all the other rotation irregularities. This supports the idea that the origin of glitches is different to that of timing noise, which comprises the unmodelled random fluctuations in the rotation rates of pulsars.Comment: 8 pages; 4 figures. Accepted for publication in MNRA

The glitch activity of neutron stars

We present a statistical study of the glitch population and the behaviour of the glitch activity across the known population of neutron stars. An unbiased glitch database was put together based on systematic searches of radio timing data of 898 rotation-powered pulsars obtained with the Jodrell Bank and Parkes observatories. Glitches identified in similar searches of 5 magnetars were also included. The database contains 384 glitches found in the rotation of 141 of these neutron stars. We confirm that the glitch size distribution is at least bimodal, with one sharp peak at approximately $20\, \rm{\mu\,Hz}$, which we call large glitches, and a broader distribution of smaller glitches. We also explored how the glitch activity $\dot{\nu}_{\rm{g}}$, defined as the mean frequency increment per unit of time due to glitches, correlates with the spin frequency $\nu$, spin-down rate $|\dot{\nu}|$, and various combinations of these, such as energy loss rate, magnetic field, and spin-down age. It is found that the activity is insensitive to the magnetic field and that it correlates strongly with the energy loss rate, though magnetars deviate from the trend defined by the rotation-powered pulsars. However, we find that a constant ratio $\dot\nu_{\rm{g}}/|\dot\nu| = 0.010 \pm 0.001$ is consistent with the behaviour of all rotation-powered pulsars and magnetars. This relation is dominated by large glitches, which occur at a rate directly proportional to $|\dot{\nu}|$. The only exception are the rotation-powered pulsars with the highest values of $|\dot{\nu}|$, such as the Crab pulsar and PSR B0540$-$69, which exhibit a much smaller glitch activity, intrinsically different from each other and from the rest of the population. The activity due to small glitches also shows an increasing trend with $|\dot\nu|$, but this relation is biased by selection effects.Comment: Accepted for publication in A&

An amplitude-phase (Ermakov-Lewis) approach for the Jackiw-Pi model of bilayer graphene

In the context of bilayer graphene we use the simple gauge model of Jackiw and Pi to construct its numerical solutions in powers of the bias potential V according to a general scheme due to Kravchenko. Next, using this numerical solutions, we develop the Ermakov-Lewis approach for the same model. This leads us to numerical calculations of the Lewis-Riesenfeld phases that could be of forthcoming experimental interest for bilayer graphene. We also present a generalization of the Ioffe-Korsch nonlinear Darboux transformationComment: FTC, 11 pp, 5 figure

A BENCHMARK STUDY OF RAPIDX, AN AIR FORCE CONTRACTING INNOVATION ORGANIZATION

The purpose of this qualitative study is to first conduct a benchmark analysis of RAPIDx, a new, agile, and innovative organization using the Government Accountability Office (GAO) Framework for Assessing the Acquisition Function at Federal Agencies for the Department of the Air Force (DAF). Second, this study provides a record of lessons learned from the implementation of the RAPIDx office from July 2018 to September 2022. Our research methodology includes a gap analysis to compare RAPIDx against two of the four cornerstones outlined within the GAO Framework. Our analysis also offers insight and visibility into RAPIDx’s effectiveness, and it informs our recommendations for evaluating new, agile, and innovative organizations. In particular, we find that RAPIDx had more areas of concern than best practices when compared against the GAO Framework. We captured 16 best practices and identified 20 areas of concern. Finally, to aid RAPIDx, we provide six recommended courses of action to address RAPIDx’s most significant area of concern, adapt the GAO Framework for innovative organizations, and improve the organization's effectiveness going forward.Captain, United States Air ForceCaptain, United States Air ForceApproved for public release. Distribution is unlimited

Prevalencia de Caries y Pérdida de Dientes en Población de 65 a 74 Años de Santiago, Chile

AbstractObjectivesTo measure prevalence of caries and tooth loss among low and middle-low socio-economic level elderly from Santiago, Chile.MethodsProportionate stratified probabilistic sampling techniques; sample of 109 people (74 women and 35 men) aged 65 to 74. Data gathered by means of a face-to-face questionnaire. Informed consent was obtained; individuals were examined by a calibrated dentist. The study was carried out from March to December 2008. Data analysis considered chi-square and ANOVA.ResultsDMFT was 24.9 (CI: 23.83; 25.96). All the individuals had caries experience; 45.9% had active caries lesions. The mean of non-treated active caries lesions was 0.9 per individual. Concerning prosthesis, 38.5% of individuals were found to use removable prosthesis and 15 people (13.76%) were edentulous.ConclusionsThe size of the gap and the importance of social environment on damaging oral health should lead to face this problem from a wider perspective of social determinants of health when building public policies

New long-term braking index measurements for glitching pulsars using a glitch-template method

Braking index measurements offer the opportunity to explore the processes affecting the long-term spin evolution of pulsars and possible evolutionary connections between the various pulsar populations. For young pulsars the long-term trends are generally obscured by short term phenomena such as timing noise and the recoveries form large glitches. Here we present a new method to overcome the latter and report on braking index measurements for the Vela-like pulsars PSR B1800-21 and PSR B1823-13, an updated measurement for Vela and new estimates for four more glitching pulsars observed at Jodrell Bank Observatory. The values of braking indices describe the long-term evolution of the pulsars across the P-P' diagram. Despite some measurements being affected by considerable uncertainties, there is evidence for a common trend involving low braking indices (n<=2) among young glitching pulsars. Such values introduce a new variant in the evolution of young pulsars and their relationship with other populations in the P-P' diagram. Low braking indices also imply that these pulsars could be a few times older than their characteristic ages. We consider PSR B1757-24 and conclude that the pulsar could be old enough to be related to the supernova remnant G5.4-1.2. Between glitches, the short-term evolution of Vela-like pulsars is characterised by large inter-glitch braking indices n_ig > 10. We interpret both short and long term trends as signatures of the large glitch activity, and speculate that they are driven by short-term post-glitch re-coupling and a cumulative long-term decoupling of superfluid to the rotation of the star.Comment: 16 pages, 6 figures. Accepted for publication in MNRA