1,104 research outputs found
Cold atomic hydrogen in the inner galaxy
The VLA is used to measure 21 cm absorption in directions with the absolute value of b less than 1 deg., the absolute value of 1 less than 25 deg. to probe the cool atomic gas in the inner galaxy. Abundant H I absorption is detected; typical lines are deep and narrow, sometimes blending in velocity with adjacent features. Unlike 21 cm emission not all allowed velocities are covered: large portions of the l-v diagram are optically thin. Although not similar to H I emission, the absorption shows a striking correspondence with CO emission in the inner galaxy: essentially every strong feature detected in one survey is seen in the other. The provisional conclusion is that in the inner galaxy most cool atomic gas is associated with molecular cloud complexes. There are few or no cold atomic clouds devoid of molecules in the inner galaxy, although these are common in the outer galaxy
The correlation between far-IR and radio continuum emission from spiral galaxies
A sample of 30 galaxies selected for their intense IRAS flux at 60 and 100 micron using the Arecibo telescope at 21 cm to measure the continuum and HI line luminosities were observed. The centimeter wave continuum correlates very well with the far-infrared flux, with a correlation coefficient as high as that found for other samples, and the same ratio between FIR and radio luminosities. Weaker correlations are seen between the FIR and optical luminosity and between the FIR and radio continuum. There is very little correlation between the FIR and the HI mass deduced from the integral of the 21 cm line. The strength of the radio continuum correlation suggests that there is little contribution to either the radio and FIR from physical processes not affecting both. If they each reflect time integrals of the star formation rate then the time constants must be similar, or the star formation rate must change slowly in these galaxies
When a 520 million-year-old Chengjiang fossil meets a modern micro-CT - a case study
The 520 million-year-old Chengjiang biota of China (UNESCO World Heritage) presents the earliest known evidence of the so-called Cambrian Explosion. Studies, however, have mainly been limited to the information exposed on the surface of the slabs. Thus far, structures preserved inside the slabs were accessed by careful removal of the matrix, in many cases with the unfortunate sacrifice of some "less important" structures, which destroys elements of exceptionally preserved specimens. Here, we show for the first time that microtomography (micro-CT) can reveal structures situated inside a Chengjiang fossil slab without causing any damage. In the present study a trilobitomorph arthropod (Xandarella spectaculum) can be reliably identified only with the application of micro-CT. We propose that this technique is an important tool for studying three-dimensionally preserved Chengjiang fossils and, most likely, also those from other biota with a comparable type of preservation, specifically similar iron concentrations
Investigation of BOLD using CARR-PURCELL T2 Weighting with SPIRAL Readout
It is demonstrated that a Carr-Purcell (CP) technique based on the fully adiabatic pulse sequence (CP-LASER) with SPIRAL readout can be used to generate zoomed images with relatively short acquisition window (at) for the investigation of the mechanisms of the BOLD effect. Based on the capability of the developed technique to refocus the dynamic dephasing, it is demonstrated that the BOLD effect is suppressed as the pulse interval cp of CP-LASER sequence decreased
Parallel Imaging with RASER using Multiband Frequency-modulated Excitation Pulses
The many advantages of the recently proposed RASER sequence have been demonstrated. Hence, RASER holds great promises for functional MRI (fMRI), particularly for studies of the orbital-frontal cortex and other brain regions near air cavities, which cause distortion and signal loss in conventional EPI methods. However, the single-shot RASER sequence implemented so far inherently presents a set of temporal and spatial limitations that hinders it feasibility and full potential for fMRI applications. It is believed that parallel imaging will help overcome such restrictions. In this work, the RASER acquisition and reconstruction scheme is extended for parallel imaging using tailored pulses for simultaneous multi-band excitation
Platinum-group element remobilisation and concentration in the Cliff chromitites of the Shetland Ophiolite Complex, Scotland
ABSTRACTThe ~492 Ma Shetland Ophiolite Complex contains an extensive mantle section, within which numerous podiform chromitite bodies formed during melt percolation in a supra-subduction zone setting. One of the Shetland ophiolite chromitite localities has an unusual style of platinum-group element (PGE) mineralization. Specifically, the Cliff chromitite suite has relatively high (>250 ppm) Pt plus Pd, compared to other chromitites in the Shetland Ophiolite Complex. In this study, we apply petrographic observation, mineral chemistry and novel X-ray microtomography data to elucidate the petrogenesis of PGE-bearing phases at Cliff. The combined datasets reveal that the PGE at Cliff have probably been fractionated by an As-rich fluid, concentrating Pt and Ir into visible (0.1–1 µm) platinum-group minerals (PGM) such as sperrylite and irarsite, respectively. The high (>1 ppm) bulk-rock concentrations of the other PGE (e.g. Os) in the Cliff chromitites suggests the presence of abundant fine-grained unidentified PGM in the serpentinized groundmass. The spatial association of arsenide phases and PGM with alteration rims on Cr-spinel grains suggests that the high Pt and Pd abundances at Cliff result from a late-stage low-temperature (e.g. 200–300°C) hydrothermal event. This conclusion highlights the potential effects that secondary alteration processes can have on modifying and upgrading the tenor of PGE deposits.</jats:p
Faculty Perspectives of Academic Integrity During COVID-19: A Mixed Methods Study of Four Canadian Universities
Faculty members are crucial partners in promoting academic integrity at Canadian universities, but their needs related to academic integrity are neither well documented nor understood. To address this gap, we developed a mixed methods survey to gather faculty perceptions of facilitators and barriers to using the existing academic integrity procedures, policies, resources, and supports required to promote academic integrity. In this article, we report the data collected from 330 participants at four Canadian universities. Responses pointed to the importance of individual factors, such as duty to promote academic integrity, as well as contextual factors, such as teaching load, class size, class format, availability of teaching assistant support, and consistency of policies and procedures, in supporting or hindering academic integrity. We also situated these results within a micro (individual), meso (departmental), macro (institutional), and mega (community) framework. Results from this study contribute to the growing body of empirical evidence about faculty perspectives on academic integrity in Canadian higher education and can inform the continued development of existing academic integrity supports at universities.Les membres du corps professoral sont des partenaires essentiels dans la promotion de l’intégrité académique dans les universités canadiennes. Toutefois, leurs besoins en cette matière ne sont ni bien documentés ni bien compris. Afin de combler cette lacune, nous avons recueilli, grâce à une méthode de recherche mixte, les perceptions des professeurs quant aux obstacles et aux facilitateurs en lien avec l’utilisation des procédures, politiques, ressources et services de soutien pour la promotion de l’intégritéacadémique. Dans cet article, nous rapportons les données recueillies auprès de 330 participants dans quatre universités canadiennes. Les réponses soulignent l’importance des facteurs individuels tels que le devoir de promouvoir l’intégrité académique. De plus, des facteurs contextuels tels que la charge d’enseignement, la taille et le format de la classe, la disponibilité du soutien d’assistants d’enseignement et la cohérence des politiques et des procédures peuvent soutenir ou entraver l’intégrité académique. Nous avons également situé ces résultats dans un cadre micro (individuel), méso (départemental), macro (institutionnel) et méga (communautaire). Les résultats de cette étude contribuent à mettre en lumière les perspectives des professeurs sur l’intégrité académiquedans l’enseignement supérieur canadien. Ils peuvent également donner un aperçu des besoins en développement professionnel et du soutien nécessaire dans les universités
Customer-engineer relationship management for converged ICT service companies
Thanks to the advent of converged communications services (often referred to as ‘triple play’), the next generation Service Engineer will need radically different skills, processes and tools from today’s counterpart. Why? in order to meet the challenges of installing and maintaining services based on multi-vendor software and hardware components in an IP-based network environment. The converged services environment is likely to be ‘smart’ and support flexible and dynamic interoperability between appliances and computing devices. These radical changes in the working environment will inevitably force managers to rethink the role of Service Engineers in relation to customer relationship management. This paper aims to identify requirements for an information system to support converged communications service engineers with regard to customer-engineer relationship management. Furthermore, an architecture for such a system is proposed and how it meets these requirements is discussed
The Inter-Rater Consistency of Clinician Ratings of Posttraumatic Stress Disorder (PTSD) Therapy Content.
Effective communication between clinicians is essential for the success of mental health interventions in multidisciplinary contexts. This relies on a shared understanding of concepts, diagnoses and treatments. A major assumption of clinicians when discussing psychological treatments with each other is that both parties have a shared understanding of the theory, rationale and application of the respective technique. We aimed to determine to what extent there is inter-rater agreement between clinicians in describing the content of group therapy sessions. Pairs of clinicians, drawn from a large multidisciplinary team (13), were asked to provide ratings of the therapeutic content and emphasis of N = 154 group therapy sessions conducted during an intensive residential treatment program for post-traumatic stress disorder (PTSD). In most therapeutic content domains there was a moderate level of agreement between clinicians regarding session content (Cohen's Kappa 0.4 to 0.6), suggesting that clinicians have a broad shared understanding of therapeutic content, but that there are also frequent discordant understandings. The implications of these findings on multidisciplinary team communication, patient care and clinical handovers are discussed and directions for further research are outlined
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