The availability of local aerial photography in southern California

Some of the major photography and photogrammetric suppliers and users located in Southern California are listed. Recent trends in aerial photographic coverage of the Los Angeles basin area are also noted, as well as the uses of that imagery

Collisional Plasma Models with APEC/APED: Emission Line Diagnostics of Hydrogen-like and Helium-like Ions

New X-ray observatories (Chandra and XMM-Newton) are providing a wealth of high-resolution X-ray spectra in which hydrogen- and helium-like ions are usually strong features. We present results from a new collisional-radiative plasma code, the Astrophysical Plasma Emission Code (APEC), which uses atomic data in the companion Astrophysical Plasma Emission Database (APED) to calculate spectral models for hot plasmas. APED contains the requisite atomic data such as collisional and radiative rates, recombination cross sections, dielectronic recombination rates, and satellite line wavelengths. We compare the APEC results to other plasma codes for hydrogen- and helium-like diagnostics, and test the sensitivity of our results to the number of levels included in the models. We find that dielectronic recombination with hydrogen-like ions into high (n=6-10) principal quantum numbers affects some helium-like line ratios from low-lying (n=2) transitions.Comment: 5 pages, 6 figures, accepted by ApJ Letter

Suppression of Aromatase in Human Breast Cells by A Cyclooxygenase-2 Inhibitor and Its Analog Involves Multiple Mechanisms Independent of Cyclooxygenase-2 Inhibition

Previous studies have demonstrated that cyclooxygenase-2 (COX-2) inhibitor NS-398 decrease aromatase activity at the transcript level in breast cancer cells. However, N-Methyl NS-398, which does not have COX-2 inhibitory activity but has very similar structure to NS-398, decreases aromatase activity and transcription in MCF-7 and MDA-MB-231 breast cells to the same extent as NS-398. This suggests that NS-398 decrease aromatase expression in breast cancer cells via other mechanism(s). Further investigations find that both compounds only decrease aromatase activity stimulated by forskolin/phorbol ester at the transcript level in both breast cancer cell lines and in breast stromal cells from patients. They do not affect aromatase expression and activity stimulated by dexamethasone. Both compounds also suppress MCF-7 cell proliferation stimulated by testosterone. Aromatase inhibition studies using placental microsomes demonstrate that the compounds show only weak direct aromatase inhibition. These results suggest that NS-398 and its N-methyl analog suppress aromatase expression and activity with multiple mechanisms

Ultrastructure, composition, and 87Sr/86Sr dating of shark teeth from lower miocene sediments of southwestern Peru

Bioapatite of fossil bone and teeth is susceptible to alteration and ion exchange during burial and diagenesis, varying its Sr content through the geological time. Nevertheless, fossil shark teeth are a powerful proxy for both chronostratigraphic and paleoecological reconstructions, thanks to the presence of the enameloid, a hard outer layer consisting of resistant fluorapatite crystallites. Here, we analyze fossil shark teeth from the Miocene sediments of the Chilcatay Formation in the Pisco Basin (southwestern Peru) with the aim of dating poorly constrained strata in this region. (Ultra)structural and compositional analyses on fossil lamniform and carcharhiniform teeth are performed through macroscopical observations, optical microscopy and SEM-EDS for evaluating the preservation state of the collected teeth. Shark teeth display a compact and well preserved outer enameloid layer formed by highly ordered bundles of crystallites that is distinctly separated by a more porous and heterogeneous inner core of dentine featuring diagenetic artefacts and microborings. Compositional mapping highlights differences in distribution of Ca, P, F, and S in the enameloid and dentine, and chemical results show a Sr content that is consistent with the range reported for extant shark teeth. The best preserved teeth were selected for Strontium Isotope Stratigraphy (SIS), measuring the 87Sr/86Sr values in the enameloid and obtaining numerical (absolute) age estimates. At the Ica River Valley, SIS dates the Chilcatay strata to the Burdigalian (between 19.1 and 18.1 Ma), in agreement with previous radiometric, isotopic and biostratigraphic ages obtained in the same region. At Media Luna, the Chilcatay strata are dated herein for the first time, resulting in a slightly older age of 21.8–20.1 Ma (late Aquitanian–early Burdigalian). These results strengthen the notion that the Sr-ratio of shark teeth can be successfully applied for obtaining reliable age estimates via SIS

The lower Pliocene elasmobranch assemblage from Arcille (Campagnatico, Grosseto Province): palaeoecological and palaeoenvironmental significance

- Tuscany hosts a conspicuous fossil record of elasmobranchs. - New stratigraphically informed studies are need to be performed. - A newly discovered elasmobranch assemblage is described from the lower Pliocene Campagnatico locality. - This diverse assemblage allows for a reconstruction of an early Pliocene marginal-marine palaeoenvironment of Tuscany

Superflares on Ordinary Solar-Type Stars

Short duration flares are well known to occur on cool main-sequence stars as well as on many types of `exotic' stars. Ordinary main-sequence stars are usually pictured as being static on time scales of millions or billions of years. Our sun has occasional flares involving up to $\sim 10^{31}$ ergs which produce optical brightenings too small in amplitude to be detected in disk-integrated brightness. However, we identify nine cases of superflares involving $10^{33}$ to $10^{38}$ ergs on normal solar-type stars. That is, these stars are on or near the main-sequence, are of spectral class from F8 to G8, are single (or in very wide binaries), are not rapid rotators, and are not exceedingly young in age. This class of stars includes many those recently discovered to have planets as well as our own Sun, and the consequences for any life on surrounding planets could be profound. For the case of the Sun, historical records suggest that no superflares have occurred in the last two millennia.Comment: 16 pages, accepted for publication in Ap

Transmission Spectra as Diagnostics of Extrasolar Giant Planet Atmospheres

Atmospheres of transiting extrasolar giant planets (EGPs) such as HD 209458 b must impose features on the spectra of their parent stars during transits; these features contain information about the physical conditions and chemical composition of the atmospheres. The most convenient observational index showing these features is the ``spectrum ratio'', defined as the wavelength-dependent ratio of spectra taken in and out of transit. I describe a model that estimates this ratio and its dependence upon parameters of the planetary atmosphere, including its cloud structure, temperature, chemical composition, and wind fields. For giant planets in close orbits, the depths of atomic and molecular features in the spectrum ratio may be as large as 0.001. Observations in visible and near-IR wavelengths using existing and planned spectrographs should be adequate to detect these features, and to provide some diagnostics of the conditions within the planetary atmosphere. I give numerous examples of such diagnostics, and I discuss their practicality.Comment: 57 pages, 22 figures. To be published in the Astrophysical Journa

Dental Morphology, Palaeoecology and Palaeobiogeographic Significance of a New Species of Requiem Shark (Genus Carcharhinus) from the Lower Miocene of Peru (East Pisco Basin, Chilcatay Formation)

Nowadays, the requiem sharks comprise one of the most diverse and widespread families of selachians, i.e., Carcharhinidae. Among the carcharhinids, the genus Carcharhinus has the largest number of living species, namely, at least 35. Known from fossils as old as the Cretaceous, the requiem sharks did not significantly radiate before the Eocene (when Carcharhinus also appeared), and their diversification mainly occurred in Neogene times. Here, we describe a new species of requiem shark, Carcharhinus dicelmai sp. nov., based on fossil teeth from Lower Miocene (18.4–18.1 Ma) strata of the Chilcatay Formation of the East Pisco Basin (southern Peru). Upper teeth of C. dicelmai sp. nov. are typically provided with a slender, smooth-edged cusp; a marked coronal twist; and a distal heel that bears 1–5 coarse, angularly lobate serrae that become more prominent toward the base of the cusp. The dentition of C. dicelmai sp. nov. appears less akin to that of most other carcharhines to the cutting-clutching type, and seemingly testifies to the development of more predominantly clutching adaptations. A carcharhinid tooth from the Burdigalian to lower Langhian Cantaure Formation of Venezuela is reassigned to C. dicelmai sp. nov., suggesting a trans-Panamanian distribution for this extinct shark species