Settlement of larval spotted sand bass (Paralabrax maculatofasciatus) within Mission Bay, San Diego CA in relation to environmental conditions

Monitoring the number of larvae that have recently settled and how this varies in relation to environmental conditions provides insight into future population strength, which is a fundamental goal of marine ecology as well as fisheries management. This research focused on characterizing the settlement patterns of spotted sand bass (Paralabrax maculatofasciatus), a recreationally important species that utilizes bays and estuaries as nursery habitat. To quantify P. maculatofasciatus settlement patterns, three larval collectors were installed near the mouth of Mission Bay, San Diego CA, and retrieved weekly from June – October of 2012 – 2015. Larvae were counted, and individuals were measured for standard length, dry weight, body condition, as well as otolith derived growth rates and age at settlement. To determine whether environmental conditions affected settlement, or individual characteristics of larvae at settlement, we examined how these factors varied in relation to chlorophyll a (Chl-a), sea surface temperature (SST), wind speed, wave height and direction, alongshore transport and upwelling. Settlement of P. maculatofasciatus was significantly lower in 2014-15, and appeared to be the result of low food conditions associated with the formation of the pacific warm anomaly, or “blob”, which reached the coast of southern California in the summer of 2014. The characteristics of larvae at settlement were also consistent with a poor feeding environment. This study has implications for understanding future settlement and recruitment of fishes in southern California, as ocean temperatures continue to rise in the face of climate change

Dimensional Stability and Acutance : An investigation into the dimensional properties of various aerial films and a study of their acutance

An experiment was run to determine if differences in drying temperature humidity conditions have any effect on the dimensional characteristics of five quite different aerial films used for various military applications. Acutance measurements were made from microdensitometer traces of each film-temperature and the data was statistically analysed. Each sample was exposed through a precision stainless steel template to a density of about 1.0. Using an optical comparitor, the difference in size between the film and the template was measured to 10-4 inch. As the image is circular, the size in any direction can be found by mere rotation on the comparitor. The length and width directions were used. The statistical analysis shows the degree to which each factor affects the results. The dimensional data agrees favorably with published data

A haloarchaeal ferredoxin electron donor that plays an essential role in nitrate assimilation

In the absence of ammonium, many organisms, including the halophilic archaeon Haloferax volcanii DS2 (DM3757), may assimilate inorganic nitrogen from nitrate or nitrite, using a ferredoxin-dependent assimilatory NO3-/NO2- reductase pathway. The small acidic ferredoxin Hv-Fd plays an essential role in the electron transfer cascade required for assimilatory nitrate and nitrite reduction by the cytoplasmic NarB- and NirA-type reductases respectively. UV–visible absorbance and EPR spectroscopic characterization of purified Hv-Fd demonstrate that this protein binds a single [2Fe–2S] cluster, and potentiometric titration reveals that the cluster shares similar redox properties with those present in plant-type ferredoxins

The Curious Case of PHL 293B : a long-lived transient in a Metal-poor Blue Compact Dwarf Galaxy

We report on small-amplitude optical variability and recent dissipation of the unusually persistent broad emission lines in the blue compact dwarf galaxy PHL 293B. The galaxy's unusual spectral features (P Cygni-like profiles with ~800 km s−1 blueshifted absorption lines) have resulted in conflicting interpretations of the nature of this source in the literature. However, analysis of new Gemini spectroscopy reveals the broad emission has begun to fade after being persistent for over a decade prior. Precise difference imaging light curves constructed with the Sloan Digital Sky Survey and the Dark Energy Survey reveal small-amplitude optical variability of ~0.1 mag in the g band offset by 100 ± 21 pc from the brightest pixel of the host. The light curve is well-described by an active galactic nuclei (AGN)-like damped random walk process. However, we conclude that the origin of the optical variability and spectral features of PHL 293B is due to a long-lived stellar transient, likely a Type IIn supernova or nonterminal outburst, mimicking long-term AGN-like variability. This work highlights the challenges of discriminating between scenarios in such extreme environments, relevant to searches for AGNs in dwarf galaxies. This is the second long-lived transient discovered in a blue compact dwarf, after SDSS1133. Our result implies such long-lived stellar transients may be more common in metal-deficient galaxies. Systematic searches for low-level variability in dwarf galaxies will be possible with the upcoming Legacy Survey of Space and Time at the Vera C. Rubin Observatory

Photoluminescence-free photoreflectance spectra using dual frequency modulation

The following article appeared in Journal of Applied Physics 102.9 (2007): 093507 and may be found at https://aip.scitation.org/doi/10.1063/1.2802991Photoreflectance (PR) spectra are usually obtained by measuring the relative change on the reflectivity of a semiconducting sample induced by a chopped laser beam. The laser beam can also produce photoluminescence (PL) emission at the sample surface which, detected at its same frequency, could appear as an offset distorting the PR spectrum. This parasitic and intrinsically noisy PL signal, not easily discriminated electronically nor optically filtered, can become the dominant part of the PR spectrum at low sample temperatures, hiding spectrum features under its associated noise, or even avoiding data acquisition. An alternative method for PL signal discrimination is proposed in this work, using a different chopping frequency for each light beam: PL and reflected signals will appear each one at its own chopping frequency, while PR signal will be detected at its frequency sum, allowing signal separation by frequency. Both experimental setups are compared using a highly luminescent quantum well structure at low temperatures. While the standard setup suffers the PL limitation, the proposed method overcomes this constraint, allowing good quality spectra to be measured at temperatures as low as 12

Monitorización del trabajo en prácticas usando un sistema decontrol de versiones

El EEES (Espacio Europeo de Educación Superior) concede un mayor protagonismo a la evaluación continua del alumnado frente a las tradicionales pruebas finales escritas. Esto supone un importante reto para el profesorado, que debe realizar un seguimiento del trabajo de un gran número de alumnos. La utilización de herramientas TIC (Tecnologías de la Información y las Comunicaciones) en este proceso cobrará un creciente protagonismo, pero es necesario definir qué herramientas serán utilizadas y cómo se integrará su uso en la dinámica educativa. En la enseñanza y en el ejercicio de la ingeniería informática es muy común el uso de sistemas de control de versiones (SCV) como apoyo al desarrollo de software. Estos sistemas permiten registrar las distintas versiones de un programa, junto con anotaciones sobre los cambios introducidos en cada versión. Este trabajo propone la utilización de un sistema de control de versiones (SCV) como método complementario de evaluación del aprendizaje del alumno por parte del profesorado, definiendo su integración en unas prácticas.Peer Reviewe

A Portable and Adaptable Fault Tolerance Solution for Heterogeneous Applications

[Abstract] Heterogeneous systems have increased their popularity in recent years due to the high performance and reduced energy consumption capabilities provided by using devices such as GPUs or Xeon Phi accelerators. This paper proposes a checkpoint-based fault tolerance solution for heterogeneous applications, allowing them to survive fail-stop failures in the host CPU or in any of the accelerators used. Besides, applications can be restarted changing the host CPU and/or the accelerator device architecture, and adapting the computation to the number of devices available during recovery. The proposed solution is built combining CPPC (ComPiler for Portable Checkpointing), an application-level checkpointing tool, and HPL (Heterogeneous Programming Library), a library that facilitates the development of OpenCL-based applications. Experimental results show the low overhead introduced by the proposal and prove its portability and adaptability benefits.This research was supported by the Ministry of Economy and Competitiveness of Spain and FEDER funds of the EU (Projects TIN2013-42148-P, TIN2016-75845-P and the predoctoral Grant of Nuria Losada Ref. BES-2014-068066), by EU under the COST Program Action IC1305, Network for Sustainable Ultrascale Computing (NESUS), and by the Galician Government (Xunta de Galicia) and FEDER funds of the EU under the Consolidation Program of Competitive Research (Ref. GRC2013/055)Xunta de Galicia; GRC 2013/05