Evaluating the Interest-Rate Risk of Adjustable-Rate Mortgage Loans

This paper evaluates the interest-rate risk inherent in an adjustable-rate mortgage (ARM) with sporadic rate adjustments and possibly binding periodic and life-of-loan rate change constraints. Simulation analysis forecasts ARM cash flows, determines the probability that constraints will hold, and partitions the loan into fixed and variable components. Simulation parameters are then altered to measure the impact of changes in contract terms and market conditions on the interest-rate risk of a typical ARM loan. Interest-rate sensitivity is found to be significantly less than that of fixed-rate loans and remarkably insensitive to changes in loan margins or initial loan rates after the first few years of an ARM's life. Therefore, it is not surprising that lenders have used these features to lure borrowers to ARMs. Periodic rate change limits and volatility in the underlying index are the only factors that influence the interest-rate risk of an existing ARM in a substantive way.

How embarrassing is that? Purchasing sensitive products and the potential for self-service

Consumers might feel uncomfortable or embarrassed when buying products that are inconsistent with the desire to project a positive self-image to others [3], [5], [7], [16]. Embarrassment and shame are key elements in the relationship between sales assistant and consumer [7] and may affect the likelihood of engagement with a service provider [10]. We explored the circumstances under which embarrassing retail experiences occur, with a view to identify the potential for self-service solutions to alleviate these experiences

Investigating planet formation in circumstellar disks: CARMA observations of RY Tau and DG Tau

(Abridged) We present CARMA observations of the thermal dust emission from the circumstellar disks around the young stars RYTau and DGTau at wavelengths of 1.3mm and 2.8mm. The angular resolution of the maps is as high as 0.15arcsec, or 20AU at the distance of the Taurus cloud, which is a factor of 2 higher than has been achieved to date at these wavelengths. The unprecedented detail of the resulting disk images enables us to address three important questions related to the formation of planets. (1) What is the radial distribution of the circumstellar dust? (2) Does the dust emission show any indication of gaps that might signify the presence of (proto-)planets? (3) Do the dust properties depend on the orbital radius? We find that modeling the disk surface density in terms of either a classical power law or the similarity solution for viscous disk evolution, reproduces the observations well. The 1.3mm image from RYTau shows two peaks separated by 0.2arcsec with a decline in the dust emission toward the stellar position, which is significant at about 2-4sigma. For both RYTau and DGTau, the dust emission at radii larger than 15 AU displays no significant deviation from an unperturbed viscous disk model. In particular, no radial gaps in the dust distribution are detected. Under reasonable assumptions, we exclude the presence of planets more massive than 5 Jupiter masses orbiting either star at distances between about 10 and 60 AU. The radial variation of the dust opacity slope, beta, was investigated by comparing the 1.3mm and 2.8mm observations. We find mean values of beta of 0.5 and 0.7 for DGTau and RYTau respectively. Variations in beta are smaller than 0.7 between 20 and 70 AU. These results confirm that the circumstellar dust throughout these disks differs significantly from dust in the interstellar medium.Comment: ApJ in press

Deep Convolutional Autoencoders as Generic Feature Extractors in Seismological Applications

The idea of using a deep autoencoder to encode seismic waveform features and then use them in different seismological applications is appealing. In this paper, we designed tests to evaluate this idea of using autoencoders as feature extractors for different seismological applications, such as event discrimination (i.e., earthquake vs. noise waveforms, earthquake vs. explosion waveforms, and phase picking). These tests involve training an autoencoder, either undercomplete or overcomplete, on a large amount of earthquake waveforms, and then using the trained encoder as a feature extractor with subsequent application layers (either a fully connected layer, or a convolutional layer plus a fully connected layer) to make the decision. By comparing the performance of these newly designed models against the baseline models trained from scratch, we conclude that the autoencoder feature extractor approach may only perform well under certain conditions such as when the target problems require features to be similar to the autoencoder encoded features, when a relatively small amount of training data is available, and when certain model structures and training strategies are utilized. The model structure that works best in all these tests is an overcomplete autoencoder with a convolutional layer and a fully connected layer to make the estimation

Adolescencia: una urgencia subjetiva

La posmodernidad podría ser concebida como una época paradójica, en donde las contradicciones parecerían ser el pan nuestro de cada día. Es importante señalar que esta lectura (paradójica) que planteamos de nuestra época no es hecha de manera arbitraria o sin fundamento. Encontramos que en la misma saltan variables que le dan consistencia a nuestra postura, las cuales podemos palparlas, por citar dos ejemplos, en el ámbito de la información y de la comunicación donde encontramos antinomias. Por un lado dentro del ámbito de la información podemos ubicar que hoy en día debido al exceso de fuentes de información es difícil poder discriminar o determinar qué de lo que leemos es efectivamente verdadero o cierto, instaurando contrariamente mayores dudas o confusiones. Mientras que en el ámbito de la comunicación podemos determinar que allí en donde hay mayor cantidad de dispositivos que nos permiten estar conectados con el mundo, tenemos menos posibilidades de comunicación con los más cercanos. De esta manera nos situamos en una época en donde la palabra globalización resuena no solamente en el ámbito económico, sino que se posiciona en la mayoría de los escenarios en los que el ser humano se desarrolla. Siendo ésta la encargada de imponernos de manera inconsciente, estilos, maneras, formas y costumbres de vida que tendrán sus repercusiones no sólo en la manera en que nos comportamos sino que además nos pasará su factura en nuestra subjetividad, poniéndonos de esta manera frente a las llamadas epidemias contemporáneas que entrarán en la clínica de las urgencias subjetivas

On the nature of the transition disk around LkCa 15

We present CARMA 1.3 mm continuum observations of the T Tauri star LkCa 15,which resolve the circumstellar dust continuum emission on angular scales between 0.2-3 arcsec, corresponding to 28-420 AU at the distance of the star. The observations resolve the inner gap in the dust emission and reveal an asymmetric dust distribution in the outer disk. (Abridge) We calculate that 90% of the dust emission arises from an azimuthally symmetric ring that contains about 5x10^{-4} M_sun of dust. A low surface-brightness tail that extends to the northwest out to a radius of about 300 AU contains the remaining 10% of the observed continuum emission. The ring is modeled with a rather flat surface density profile between 40 and 120 AU, while the inner cavity is consistent with either a sharp drop of the 1.3 mm dust optical depth at about 42 AU or a smooth inward decrease between 3 and 85 AU. (Abridge). Within 40 AU, the observations constrain the amount of dust between 10^{-6} and 7 Earth masses, where the minimum and maximum limits are set by the near-IR SED modeling and by the mm-wave observations of the dust emission respectively. In addition, we confirm the discrepancy in the outer disk radius inferred from the dust and gas, which corresponds to 150 AU and 900 AU respectively. We cannot reconcile this difference by adopting an exponentially tapered surface density profile as suggested for other systems, but we instead suggest that the gas surface density in the outer disk decreases less steeply than that predicted by model fits to the dust continuum emission. The lack of continuum emission at radii lager than 120 AU suggests a drop of at least a factor of 5 in the dust-to-gas ratio, or in the dust opacity. We show that a sharp dust opacity drop of this magnitude is consistent with a radial variation of the grain size distribution as predicted by existing grain growth models.Comment: Accepted for publication on ApJ, 13 pages, 11 figure

Interface-tuned epoxy/clay nanocomposites

Though interface has been known for a critical role in determining the properties of conventional composites, its role in polymer nanocomposites is still fragmented and in its infancy. This study synthesized a series of epoxy/clay nanocomposites with different interface strength by using three types of modifiers: ethanolamine (denoted ETH), Jeffamine� M2070 (M27) and Jeffamine� XTJ502 (XTJ). XTJ created a strong interface between clay layers and matrix because it bridged the layers with matrix by a chemical reaction as proved by Fourier transform infrared spectroscopy; M27 produced an interme-diate interface strength due to the molecular entanglement between grafted M27 chains and matrix molecules; the interface made by ETH was weak because neither chemical bridging nor molecular entanglement was involved. The studies of mechanical and thermal properties and morphology at a wide range of magnification show that the strong interface promoted the highest level of exfoliation and dispersion of clay layers, and achieved the most increment in Young’s modulus, fracture toughness and glass transition temperature (Tg) of matrix. With w1.3 wt% clay, the critical strain energy release rate G1c of neat epoxy improved from 179.0 to 384.7 J/m, 115% improvement and Tg enhanced from 93.7 to 99.

Clinical manifestations and epidemiology of adolescent tuberculosis in Ukraine

BACKGROUND: During adolescence, childhood and adult forms of tuberculosis (TB) overlap, resulting in diverse disease manifestations. Knowing which patient characteristics are associated with which manifestations may facilitate diagnosis and enhance understanding of TB pathophysiology. METHODS: In this cross-sectional study, we included 10-19-year-olds in Ukraine\u27s national TB registry who started TB treatment between 2015 and 2018. Using multivariable regression, we estimated associations between patient characteristics and four presentations of TB: pleural, extrathoracic, cavitary and rifampicin-resistant (RR). We also described the epidemiology of adolescent TB in Ukraine. RESULTS: Among 2491 adolescent TB cases, 88.4% were microbiologically confirmed. RR-TB was confirmed in 16.9% of new and 29.7% of recurrent cases. Of 88 HIV-infected adolescents, 59.1% were not on antiretroviral therapy at TB diagnosis. Among 10-14-year-olds, boys had more pleural disease (adjusted OR (aOR) 2.12, 95% CI: 1.08-4.37). Extrathoracic TB was associated with age 15-19 years (aOR 0.26, 95% CI: 0.18-0.37) and HIV (aOR 3.25, 95% CI: 1.55-6.61 in 10-14-year-olds; aOR 8.18, 95% CI: 3.58-17.31 in 15-19-year-olds). Cavitary TB was more common in migrants (aOR 3.53, 95% CI: 1.66-7.61) and 15-19-year-olds (aOR 4.10, 95% CI: 3.00-5.73); among 15-19-year-olds, it was inversely associated with HIV (aOR 0.32, 95% CI: 0.13-0.70). RR-TB was associated with recurrent disease (aOR 1.87, 95% CI: 1.08-3.13), urban residence (aOR 1.27, 95% CI: 1.01-1.62) and cavitation (aOR 2.98, 95% CI: 2.35-3.78). CONCLUSIONS: Age, sex, HIV and social factors impact the presentation of adolescent TB. Preventive, diagnostic and treatment activities should take these factors into consideration