Widening of Protostellar Outflows: an Infrared Outflow Survey in Low Luminosity Objects

We present an outflow survey toward 20 Low Luminosity Objects (LLOs), namely protostars with an internal luminosity lower than 0.2 Lsun. Although a number of studies have reported the properties of individual LLOs, the reasons for their low luminosity remain uncertain. To answer this question, we need to know the evolutionary status of LLOs. Protostellar outflows are found to widen as their parent cores evolve, and therefore, the outflow opening angle could be used as an evolutionary indicator. The infrared scattered light escapes out through the outflow cavity and highlights the cavity wall, giving us the opportunity to measure the outflow opening angle. Using the Canada-France-Hawaii Telescope, we detected outflows toward eight LLOs out of 20 at Ks band, and based on archival Spitzer IRAC1 images, we added four outflow-driving sources from the remaining 12 sources. By fitting these images with radiative transfer models, we derive the outflow opening angles and inclination angles. To study the widening of outflow cavities, we compare our sample with the young stellar objects from Arce & Sargent 2006 and Velusamy et al. 2014 in the plot of opening angle versus bolometric temperature taken as an evolutionary indicator.Our LLO targets match well the trend of increasing opening angle with bolometric temperature reported by Arce & Sargent and are broadly consistent with that reported by Velusamy et al., suggesting that the opening angle could be a good evolutionary indicator for LLOs. Accordingly, we conclude that at least 40% of the outflow-driving LLOs in our sample are young Class 0 objects.Comment: Accepted for publication in AJ, 13 pages, 9 figure

Administration Service for the Tourist Information System (TIP)

The modern day tourists do not want to deal with the hassle of using a large number of travel guides and paper maps while travelling. They would prefer to be able to access required information via their mobile phones or Personal Digital Assistants (PDAs). We realise that the delivered information may be originally available in numerous information formats. To support the administrator of the tourist guides the programme is required to help sorting information from these different sources and to help inserting them into a system. Our goal with this project is to develop a software support for processing information import via a graphical user interface, to support the administrator in identifying and extracting the appropriate sight information from various resources. The interface also helps in transferring and storing the structured and unstructured data into the TIP database

SYNTHESES, STRUCTURES AND PROPERTIES OF NANOPOROUS METAL-ORGANIC FRAMEWORK MATERIALS

This dissertation describes the synthesis and characterization of a number of extended framework materials. Firstly, a series of transition metal and lanthanide metal-organic framework materials (MOFs) possessing both two and three-dimensional (2-D/ 3-D) structures as a result of linkage with different rigid carboxylate ligands have been synthesized. The crystal structures have been determined by single crystal X-ray diffraction, and their thermal/ structural stability evaluated by thermogravimetric analysis, powder neutron diffraction, in-situ and combined synchrotron powder X-ray and Raman spectroscopy. The structural stability strongly relates to the dimensionality and chemical bonding within the frameworks. In this dissertation, a geometric strategy has been proposed to elucidate these complex structures. A nanoporous structure stable up to 500oC can be obtained by dehydrating holmium MOF with 1, 3, 5-Benzene tricarboxylic acid (H3BTC) ligand. Its porosity is shown to be 879.1m2/g specific surface area by gas isotherm experiments and absorbing 1.46wt% excess of hydrogen at 77K. High resolution neutron powder diffraction has been performed on the dehydrated Ho-MOF-BTC system with P4122 chiral space group under different deuterium gas pressures and a new mechanism for gas adsorption in framework materials. A unique "helical" deuterium adsorption phenomenon results from direct interaction between the guest molecules and the non-centrosymmetric (chiral) framework architecture. Reconstruction of the nuclear scattering density using the charge flipping method has been utilized as a novel strategy for the qualitative analysis of the adsorbed molecules, in combination with maximum entropy method (MEM) density maps that provide quantitative information of the exact distribution of the diffusion pathways. In addition, the structure, magnetic and photo-luminescent properties of three lanthanide- and transition metal MOFs with shorter formate ligand are investigated by single crystal X-ray and neutron diffraction as well as solid-state fluorescence spectroscopy techniques, demonstrating unusual magnetic behaviors of Co-formate systems and strongly characteristic emission spectra from europium (Eu(III)) and terbium (Tb(III)) compounds

Family Theory Framework and Case Analysis using AI Tools

In this assignment, students will utilize AI tools, like ChatGPT, to analyze a case study in social work practice and generate recommendations for intervention strategies and treatment plans based on a selected family theory and framework. Students will critically evaluate the responses provided by ChatGPT, considering its strengths and limitations in addressing the client\u27s needs. This assignment aims to comprehend the knowledge of family theory and framework, and enhance students\u27 critical thinking skills, ethical decision-making, and understanding of the role of AI in social work practic

A Geometric View on Constrained M-Estimators

We study the estimation error of constrained M-estimators, and derive explicit upper bounds on the expected estimation error determined by the Gaussian width of the constraint set. Both of the cases where the true parameter is on the boundary of the constraint set (matched constraint), and where the true parameter is strictly in the constraint set (mismatched constraint) are considered. For both cases, we derive novel universal estimation error bounds for regression in a generalized linear model with the canonical link function. Our error bound for the mismatched constraint case is minimax optimal in terms of its dependence on the sample size, for Gaussian linear regression by the Lasso