Bard Early College: Milestones, Looking Back

The author, whose professional experience includes serving as the founding principal of the first Bard High School Early College, maps the milestones of that experience and others through decades of early college leadership. Focusing on anecdotes and personal stories, this essay gives voice and texture to discourse about early college then and now as well as students, teachers, and the future of Bard\u27s High School Early College program

Near Infrared Spectroscopy of Young Brown Dwarfs in Upper Scorpius

Spectroscopic follow-up is a pre-requisite for studies of the formation and early evolution of brown dwarfs. Here we present IRTF/SpeX near-infrared spectroscopy of 30 candidate members of the young Upper Scorpius association, selected from our previous survey work. All 24 high confidence members are confirmed as young very low mass objects with spectral types from M5 to L1, 15-20 of them are likely brown dwarfs. This high yield confirms that brown dwarfs in Upper Scorpius can be identified from photometry and proper motions alone, with negligible contamination from field objects (<4%). Out of the 6 candidates with lower confidence, 5 might still be young very low mass members of Upper Scorpius, according to our spectroscopy. We demonstrate that some very low mass class II objects exhibit radically different near infrared (0.6 - 2.5micron) spectra from class III objects, with strong excess emission increasing towards longer wavelengths and partially filled in features at wavelengths shorter than 1.25micron. These characteristics can obscure the contribution of the photosphere within such spectra. Therefore, we caution that near infrared derived spectral types for objects with discs may be unreliable. Furthermore, we show that the same characteristics can be seen to some extent in all class II and even a significant fraction of class III objects (~40%), indicating that some of them are still surrounded by traces of dust and gas. Based on our spectra, we select a sample of objects with spectral types of M5 to L1, whose near-infrared emission represents the photosphere only. We recommend the use of these objects as spectroscopic templates for young brown dwarfs in the future.Comment: 12 pages, 9 figures, Accepted in MNRA

Geostrophic transport in the Brazil current region north of 20°S

Geostrophic volume transports in the upper 500 m are computed from historical hydrographic data for the area off the Brazilian coast west of 30°W and between 7° and 20°S. On the basis of water mass distributions, potential density surfaces of σθ = 27.05 kg m−3 (360–670 m) and σθ = 27.6 kg m−3 (∼1200 m) are used for referencing the meridional and zonal components of the geostrophic shears, respectively. Near 15°S a northwestward flow of 8 Sv crosses 30°W. This current reaches the shelf near 10°S in February and March, the only two months for which observations are available near that latitude along the coast; of the 8 Sv, about 4 Sv continue towards the northwest into the North Brazil Current while another branch also carrying 4 Sv turns southward as the beginning of the Brazil Current. Between 10° and 20°S the Brazil Current does not appear to strengthen appreciably, but because of the likely existence of flow on the shelf these transport values represent lower limits to the actual ones. At 30°W, another westward flow of approximately 8–10 Sv enters the area near 10°S and serves to strengthen the North Brazil Current. The total transfer of 12 Sv or more from the South Equatorial Current into the North Brazil Current and later to other currents and the northern hemisphere may be an important factor contributing to the well-known weakness of the Brazil Current in its more northerly latitudes

Optical Continuum and Emission-Line Variability of Seyfert 1 Galaxies

We present the light curves obtained during an eight-year program of optical spectroscopic monitoring of nine Seyfert 1 galaxies: 3C 120, Akn 120, Mrk 79, Mrk 110, Mrk 335, Mrk 509, Mrk 590, Mrk 704, and Mrk 817. All objects show significant variability in both the continuum and emission-line fluxes. We use cross-correlation analysis to derive the sizes of the broad Hbeta-emitting regions based on emission-line time delays, or lags. We successfully measure time delays for eight of the nine sources, and find values ranging from about two weeks to a little over two months. Combining the measured lags and widths of the variable parts of the emission lines allows us to make virial mass estimates for the active nucleus in each galaxy. The virial masses are in the range 10^{7-8} solar masses.Comment: 24 pages, 16 figures. Accepted for publication in Ap

Collaborative Learning: Students’ Perspectives on How Learning Happens

Collaborative learning (CL), a core component of inquiry-based learning approaches, aims to support students’ development of key skills (e.g., working in multidisciplinary teams). To design effective CL activities, we need to understand students’ perceptions about CL. However, few studies have examined students’ understandings of CL. This qualitative study aimed to address this gap by analyzing participants’ constructions of their CL experiences. Focus group data (14 first- and 14 fourth-year dental student volunteers) were analyzed by an inductive thematic analysis strategy. The findings explained students’ perspectives of key factors for facilitating positive learning within an inquiry-based CL context, namely having a “right” mix of students and facilitating balanced participation and interactions, especially questioning, explaining, and managing knowledge conflicts and understanding their thinking processes when learning

Comparison of Gastrocnemius Shear Wave Elastography Stiffness Over 5 Different Zones

A few studies report that shear wave elastography (SWE) is a reliable method of measuring gastrocnemius muscle stiffness. To date there are no studies assessing variance in stiffness measures at different locations on the muscle. This led us to ask whether the spot at which gastrocnemius stiffness is measured matters. PURPOSE: To determine if measurement site on the medial and lateral gastrocnemius affects SWE stiffness values. METHODS: Twelve subjects (3 men, 9 women) completed this study (Mean age is 23.0 (SD = 1.0) for men and 21.7 (SD = 2.0) for women (t p = 0.3035). Mean height (cm) is 179.5 (SD = 2.9) for men and 167.1 (SD = 7.8) for women (t p = 0.0256). Mean weight (kg) is 74.9 (SD =10.4) for men and 62.5 (SD = 9.7) for women (t p = 0.0892). Subjects wore shorts and lay prone on a treatment table with their bare feet hanging off the edge of the table. Ultrasound images to confirm borders of the medial and lateral gastrocnemius were confirmed and marked. SWE of both the Medial head (MG) and lateral head (LG) were taken with each head area divided into 4 zones (1=superior medial, 2=superior lateral, 3=inferior medial, 4= inferior lateral). A fifth zone was collected at the center of the muscle at 70% of the length of the lateral malleolus to lateral femoral epicondyle. All 5 points were assessed for SWE in both a relaxed and neutral (900) ankle joint position. Three separate elastogram frames were used to calculate muscle stiffness using both the velocity (m/s) and young’s modulus model (kPa) utilizing an overall area analysis for each. RESULTS: MG velocity and kPa values were significantly greater than LG in the relaxed and neutral positions (pCONCLUSION: MG stiffness is greater than LG regardless of position while intrinsic stiffness of MG increases more relative to LG when placed in neutral. Measurement of stiffness is best represented at the center of the muscle belly in the neutral position, but zones 2,3 and 5 produce similar stiffness values in the relaxed position

A bacterial artificial chromosome library for the Australian saltwater crocodile (Crocodylus porosus) and its utilization in gene isolation and genome characterization

Background Crocodilians (Order Crocodylia) are an ancient vertebrate group of tremendous ecological, social, and evolutionary importance. They are the only extant reptilian members of Archosauria, a monophyletic group that also includes birds, dinosaurs, and pterosaurs. Consequently, crocodilian genomes represent a gateway through which the molecular evolution of avian lineages can be explored. To facilitate comparative genomics within Crocodylia and between crocodilians and other archosaurs, we have constructed a bacterial artificial chromosome (BAC) library for the Australian saltwater crocodile, Crocodylus porosus. This is the first BAC library for a crocodile and only the second BAC resource for a crocodilian. Results The C. porosus BAC library consists of 101,760 individually archived clones stored in 384-well microtiter plates. Not I digestion of random clones indicates an average insert size of 102 kb. Based on a genome size estimate of 2778 Mb, the library affords 3.7 fold (3.7×) coverage of the C. porosus genome. To investigate the utility of the library in studying sequence distribution, probes derived from CR1a and CR1b, two crocodilian CR1-like retrotransposon subfamilies, were hybridized to C. porosusmacroarrays. The results indicate that there are a minimum of 20,000 CR1a/b elements in C. porosus and that their distribution throughout the genome is decidedly non-random. To demonstrate the utility of the library in gene isolation, we probed the C. porosus macroarrays with an overgo designed from a C-mos (oocyte maturation factor) partial cDNA. A BAC containing C-mos was identified and the C-mos locus was sequenced. Nucleotide and amino acid sequence alignment of the C. porosus C-mos coding sequence with avian and reptilian C-mos orthologs reveals greater sequence similarity between C. porosus and birds (specifically chicken and zebra finch) than between C. porosus and squamates (green anole). Conclusion We have demonstrated the utility of the Crocodylus porosus BAC library as a tool in genomics research. The BAC library should expedite complete genome sequencing of C. porosus and facilitate detailed analysis of genome evolution within Crocodylia and between crocodilians and diverse amniote lineages including birds, mammals, and other non-avian reptiles

Remote sensing and geologic studies of the orientale basin region

Both visual and near-infrared spectral observations are combined with multispectral imaging to study the Orientale interior and exterior, the Cruger region, Grimaldi Region, the Schiller-Schickard Region, and the Humorum Region of the Moon. It was concluded that anorthosites occur in the Inner Rook Mountains of Orientale, the inner ring of Grimaldi, and the main ring of Humorum. Imaging spectroscopy shows that the entire eastern Inner Rook Mountains are composed of anorthosites. Orientale ejecta are strikingly like the surface materials in the region where Apollo 16 landed. This similarity indicates similar mineralogy, i.e., noritic anorthosite. Thus, Orientile ejecta is more mafic than the Inner Rook Mountains. This situation is also true for the Nectaris, Humorum, and Gramaldi basins. Isolated areas of the Orientale region show the presence of gabbroic rocks, but, in general, Orientale ejecta are noritic anorthosites, which contain much more low-Ca pyroxene than high-Ca pyroxene. Ancient (pre-Orientale) mare volcanism apparently occurred in several areas of the western limb

Upper-level circulation in the South Atlantic Ocean

In this paper we present a literature survey of the South Atlantic's climate and its oceanic upper-layer circulation and meridional heat transport. The opening section deals with climate and is focused upon those elements having greatest oceanic relevance, i.e., distributions of atmospheric sea level pressure, the wind fields they produce, and the net surface energy fluxes. The various geostrophic currents comprising the upper-level general circulation are then reviewed in a manner organized around the subtropical gyre, beginning off southern Africa with the Agulhas Current Retroflection and then progressing to the Benguela Current, the equatorial current system and circulation in the Angola Basin, the large-scale variability and interannual warmings at low latitudes, the Brazil Current, the South Atlantic Current, and finally to the Antarctic Circumpolar Current system in which the Falkland (Malvinas) Current is included. A summary of estimates of the meridional heat transport at various latitudes in the South Atlantic ends of the surve

Remote sensing and geologic studies of the terrain northwest of Humorum basin

A portion of the highlands terrain northwest of the Humorum basin, a large multiringed impact structure on the southwestern portion of the lunar nearside, exhibits anomalous characteristics in several remote sensing data sets. A variety of remote sensing studies of the terrain northwest of Humorum basin were performed in order to determine the composition and origin of the anomalous unit as well as the composition of the highland material exposed by the Humorum impact event. It was found that at least a portion of the mare-bounding ring of Humorum is composed of pure anorthosite. Other details of the study are reported