C3H2 observations as a diagnostic probe for molecular clouds

Recently the three-membered ring molecule, cyclopropenylidene, C3H2, has been identified in the laboratory and detected in molecular clouds by Thaddeus, Vrtilek and Gottlieb (1985). This molecule is wide-spread throughout the Galaxy and has been detected in 25 separate sources including cold dust clouds, circumstellar envelopes, HII regions, and the spiral arms observed against the Cas supernova remnant. In order to evaluate the potential of C3H2 as a diagnostic probe for molecular clouds, and to attempt to identify the most useful transitions, statistical equilibrium calculations were carried out for the lowest 24 levels of the ortho species and the lowest 10 levels of the para species. Many of the sources observed by Matthews and Irvine (1985) show evidence of being optically thick in the 1(10)-1(01) line. Consequently, the effects of radiative trapping should be incorporated into the equilibrium calculations. This was done using the Large Velocity Gradient approximation for a spherical cloud of uniform density. Some results of the calculations for T(K)=10K are given. Figures are presented which show contours of the logarithm of the ratio of peak line brightness temperatures for ortho-para pairs of lines at similar frequencies. It appears that the widespread nature of C3H2, the relatively large strength of its spectral lines, and their sensitivity to density and molecular abundance combine to make this a useful molecule for probing physical conditions in molecular clouds. The 1(10)-1(01) and 2(20)-2(11) K-band lines may be especially useful in this regard because of the ease with which they are observed and their unusual density-dependent emission/absorption properties

Multi-level study of C3H2: The first interstellar hydrocarbon ring

Cyclic species in the interstellar medium have been searched for almost since the first detection of interstellar polyatomic molecules. Eleven different C3H2 rotational transitions were detected; 9 of which were studied in TMC-1, a nearby dark dust cloud, are shown. The 1 sub 10 yields 1 sub 01 and 2 sub 20 yields 2 sub 11 transitions were observed with the 43 m NRAO telescope, while the remaining transitions were detected with the 14 m antenna of the Five College Radio Observatory (FCRAO). The lines detected in TMC-1 have energies above the ground state ranging from 0.9 to 17.1 K and consist of both ortho and para species. Limited maps were made along the ridge for several of the transitions. The HC3N J = 2 yields 1 transition were mapped simultaneously with the C3H2 1 sub 10 yields 1 sub 01 line and therefore can compare the distribution of this ring with a carbon chain in TMC-1. C3H2 is distributed along a narrow ridge with a SE - NW extension which is slightly more extended than the HC2N J = 2 yields 1. Gaussian fits gives a FWHP extension of 8'5 for C3H2 while HC3N has a FWHP of 7'. The data show variations of the two velocity components along the ridge as a function of transition. Most of the transitions show a peak at the position of strongest HC3N emission while the 2 sub 21 yields 2 sub 10 transition shows a peak at the NH3 position

Development of a high capacity toroidal Ni/Cd cell

A nickel cadmium battery design which can offer better thermal management, higher energy density and much lower cost than the state-of-the-art is emphasized. A toroidal Ni/Cd cell concept is described. It was critically reviewed and used to develop two cell designs for practical implementation. One is a double swaged and the other a swaged welded configuration

Closed-circuit television welding- electrode guidance system

Closed-circuit TV camera is mounted parallel to electrode and moves along with it. Camera is scanned along seam so seam is viewed parallel with scan lines on TV monitor. Two fiber optics illuminators are attached to guidance system; they illuminate seam for TV camera

Submillimetre CO observations of the Cepheus A outflow

The authors have carried out spectral mapping of the Cep A region in the J = 3-2 transition of CO. The high velocity wings symptomatic of outflowing gas are evident over a region ~6×6 arc min in extent (~1.3×1.3 pc). There appear to be 2 outflows, as found also for HCO+ by Loren et al. (1985). The CO J = 3-2 red wing intensity is enhanced relative both to lower transition CO data and to HCO+ J = 1-0, particularly to the south and east of Cep A, a result which suggests the presence of hot, optically thin gas in the flow. No such significant enhancement is seen, however, in the blue wing. The data are discussed in terms of a 2 component outflow in which the HCO+ emission originates mainly from dense clumps in the flow while a less dense (but >4×104cm-3) interclump medium is responsible for most of the 12CO emission

Evaluating approaches for estimating peat depth

Estimates of peat depth are required to inform understanding of peatland development, functioning, and ecosystem services such as carbon storage. However, there is a considerable lack of peat depth data at local, national, and global scales. Recent studies have attempted to address this knowledge deficit by using manual probing and ground-penetrating radar (GPR) to estimate depth. Despite increasing application, little consideration has been given to the accuracy of either of these techniques. This study examines the accuracy of probing and GPR for measuring peat depth. Corresponding GPR and probing surveys were carried out at a catchment scale in a blanket peatland. GPR depth estimations, calibrated using common midpoint (CMP) surveys, were found to be on average 35% greater than probe measurements. The source of disagreement was found to be predominantly caused by depth probes becoming obstructed by artifacts within the peat body, although occasionally probing rods also penetrated sediments underlying the peat. Using the Complex Refractive Index Model, it was found that applying a single velocity of 0.036 m ns−1 across a single site may also result in −8 to +17% error in estimation of peat depth due to spatial variability in water content and porosity. It is suggested that GPR calibrated at each site using CMP surveys may provide a more accurate method for measuring peat depth

An Investigation Into Mentoring Practices of Faculty Who Mentor Undergraduate Researchers at a Hispanic Serving Institution

Research has shown the benefits of undergraduate research; however, few studies have examined mentors of undergraduate researchers. The purpose of this study was to investigate the practices of mentors who have successfully mentored Hispanic undergraduate researchers. Findings from this study suggested that mentors should focus on interacting with students, listen to and understand students’ interests, be organized, require students to be responsible, and monitor students’ work. Recommendations for practice and research have been provided. ResumenLa investigación ha demostrado los beneficios de investigación de pregrado, sin embargo, pocos estudios han examinado mentores de investigación de pregrado. El propósito de este estudio fue el de investigar las prácticas de menores que han guiado exitosamente investigadores hispanos de pregrado. Los hallazgos sugieren que los mentores deben enfocarse en la interacción con los estudiantes, escuchar y entender intereses estudiantiles, ser organizados, requerir que los estudiantes sean responsables, y monitorear el trabajo de los estudiantes. Recomendaciones prácticas para la investigación se proveen

An Investigation Into Mentoring Practices of Faculty Who Mentor Undergraduate Researchers at a Hispanic Serving Institution

Research has shown the benefits of undergraduate research; however, few studies have examined mentors of undergraduate researchers. The purpose of this study was to investigate the practices of mentors who have successfully mentored Hispanic undergraduate researchers. Findings from this study suggested that mentors should focus on interacting with students, listen to and understand students’ interests, be organized, require students to be responsible, and monitor students’ work. Recommendations for practice and research have been provided. ResumenLa investigación ha demostrado los beneficios de investigación de pregrado, sin embargo, pocos estudios han examinado mentores de investigación de pregrado. El propósito de este estudio fue el de investigar las prácticas de menores que han guiado exitosamente investigadores hispanos de pregrado. Los hallazgos sugieren que los mentores deben enfocarse en la interacción con los estudiantes, escuchar y entender intereses estudiantiles, ser organizados, requerir que los estudiantes sean responsables, y monitorear el trabajo de los estudiantes. Recomendaciones prácticas para la investigación se proveen