5,371 research outputs found
An evaluation of the uptake of community drug checking services and its effect on risk reduction practices in British Columbia
No full textBackground: In response to a growing toxic drug crisis, drug checking services (DCS) have been implemented across British Columbia (BC). DCS have been offered in various settings (e.g., festivals, community) using different technologies (e.g., Fourier-transform infrared spectroscopy [FTIR]), though little is known about the uptake of DCS and its influence on behaviour. This thesis aims to examine characteristics shaping frequent utilization of DCS and the effect of DCS on behaviour change specific to reducing risk of harms.
Methods: Data were derived from a cross-sectional study administered across BC. Multivariable logistic regression models were utilized to investigate: 1) factors associated with frequency of DCS utilization and 2) the effect of attitude towards DCS results (i.e., not pleased vs. pleased) on engagement in risk reduction practices (i.e., disposed of drug, used less). Using descriptive statistics, we also examined whether specific risk reduction practices differed based on being pleased (or not) with DCS results.
Results: Amongst 321 participants, 152 (47.4%) utilized drug checking once. Factors positively associated with frequent drug checking utilization included having witnessed an overdose (Adjusted Odds Ratio [AOR] = 2.71; 95% Confidence Interval [CI}: 1.52 – 5.00) and having accessed healthcare services (AOR = 1.94; 95% CI: 1.06 – 3.61), whereas those who self-identified as Indigenous, Black, or Person of Colour (AOR = 0.45; 95% CI: 0.26 – 0.76) and those who had an outstanding warrant (AOR = 0.48; 95% CI: 0.24 – 0.94) were negatively associated with the outcome. Amongst 288 participants, 77 (26.7%) were not pleased with their results which was positively associated with engagement in a risk reduction practice (AOR = 4.00; 95% CI: 1.72 – 9.09). While most participants reported no behaviour change, the most reported risk reduction practices were disposing of the drug (18; 23.4%) and selling the drug (10; 4.7%) for participants not pleased and pleased with their results respectively.
Conclusions: Findings from this thesis suggest that various facilitators and barriers might influence frequent and continued DCS utilization. Additionally, we found that attitudes regarding DCS results can play an important role in determining behaviour change, further emphasizing the potential of DCS to reduce risk associated with substance use.Medicine, Faculty ofGraduat
Characterization of overdose survivors and their outcomes in opioid agonist treatment : findings from a pragmatic, pan-Canadian, randomized control trial
No full textBackground: Canada is currently facing an overdose epidemic primarily attributed to prescription and synthetic opioids. Previous work has revealed that individuals with a history of non-fatal overdose (NFO) are at a higher risk of mortality, but little is known about treatment outcomes among this population. The aim of this thesis was to characterize opioid agonist treatment (OAT) seeking individuals with prescription-type opioid use disorder (POUD) and a history of NFO, as well as their treatment outcomes.
Methods: Data were drawn from OPTIMA, a multi-site, 24-week, pragmatic, randomized control trial evaluating the relative effectiveness of buprenorphine/naloxone and methadone models of care for adults with POUD. Multivariable logistic regression was used to determine correlates of NFO and to explore treatment retention among participants with a history of NFO. Analysis of covariance (ANCOVA) was used to examine the mean difference in opioid use between treatment arms. Finally, descriptive statistics were produced to determine the prevalence of overdose during treatment and investigate patterns of opioid use before and after overdose.
Results: Among the 272 randomized participants, 159 (58%) had a lifetime history of NFO. Homelessness, receiving income assistance and positive urine drug screens (UDS) for fentanyl and methamphetamine were all independently associated with a history of NFO. Among participants with a history of NFO, retention was 17% for the buprenorphine/naloxone group and 18% for the methadone group and was not statistically different between the treatment arms (p = 0.54). Across the study period, there was an 11.9% adjusted mean difference in opioid-free UDS, favouring the buprenorphine/naloxone arm (95% CI= 3.5 to 20.3; p=0.0057). A total of 24 overdoses were reported during the study period (6 participants randomized to buprenorphine/naloxone; 12 randomized to methadone). All participants that initiated treatment continued to use opioids after overdose.
Conclusions: Findings from this research indicate that a considerable proportion of OAT-seeking individuals have a history of NFO. Low retention rates and high opioid use in treatment highlight the importance of an individualized, multidimensional approach to treatment for this population. Timely initiation of low-barrier treatment and interventions to address socio-structural barriers could potentially mitigate future overdose and improve treatment outcomes.Medicine, Faculty ofMedicine, Department ofGraduat
Lateral Inverse Proximity Effect in Ti/Au Transition Edge Sensors
No full textWe report measured Tc of superconducting Ti/Au bilayer strips with a width W varying from 5 to 50 µm. The strips were fabricated based on a Ti/Au bilayer that consists of a 41-nm-thick Ti layer to which a 280-nm-thick Au layer was added. We find that the Tc drops as W decreases and the declining trend almost perfectly follows Tc/ [mK] = - 738.4 [μ m] 2/ W2+ 91.0 , where Tc(W= ∞) of 91 mK is consistent with the intrinsic Tc of the bilayer. The result is interpreted as a consequence of the lateral inverse proximity effect originated in normal-metal microstructures, namely Au overhangs that exist at the edges of the Ti/Au bilayer. The Tc shift from the intrinsic Tc should be anticipated in addition to the longitudinal proximity effect from superconducting Nb leads when one designs Ti/Au TESs.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.ImPhys/Optic
Leaving the Hospital Against Medical Advice Among People Who Use Illicit Drugs: A Systematic Review
No full textImproving hospital care for patients who use illicit drugs in Vancouver, Canada
No full textBackground: People who use illicit drugs (PWUD) experience a number of health-related harms that often lead to frequent hospitalizations. However, there exists little scientific evidence that has explored utilization and retention in hospital care, including leaving hospital against medical advice (AMA), among this population. The objective of this thesis is to provide evidence to improve hospital care for PWUD by first, identifying individual and contextual factors associated with leaving hospital AMA and other hospital-related experiences; and, second, to use these findings to develop and evaluate novel approaches to minimizing the risks and harms that PWUD experience in hospital settings. Methods: This dissertation draws on data collected from two open prospective cohort studies of HIV-positive and HIV-negative PWUD in Vancouver, Canada. These data were confidentially linked to a hospital discharge database as well as comprehensive records of HIV treatment and related clinical outcomes through a clinical monitoring laboratory. A variety of longitudinal and cross-sectional analytic techniques were used to examine the impact of intersecting individual and contextual factors on various hospital service outcomes. Results: This dissertation identified hospitals as a risk environment for PWUD, given the high prevalence of hospital discharge AMA and active illicit drug use in hospitals. The study findings highlighted various risk and protective factors for leaving hospital AMA, and discussed the negative consequences of being denied pain medication on illicit drug use in hospitals. The findings from this dissertation also point to novel strategies that may address these issues, including the implementation of an adult HIV/AIDS integrated health program operating in proximity to a hospital to minimize hospital discharge AMA among HIV-positive PWUD, as well as the potential for an in-hospital supervised injection facility (SIF) to reduce the harms associated with illicit drug use in hospital. Conclusion: Despite this setting of universal access to healthcare, there are individual- and contextual-level factors that play a pivotal role in shaping utilization and retention in hospital care among PWUD. The collective findings of this dissertation offer insights into how integrated harm reduction-based interventions may mitigate the risks associated with leaving hospital AMA and active illicit drug use in hospitals.Medicine, Faculty ofPopulation and Public Health (SPPH), School ofGraduat
Revealing the influence of Mo addition on interphase precipitation in Ti-bearing low carbon steels
No full textMo is widely used as an effective microalloying element to improve mechanical performance of interphase precipitation steels, but the precise role of Mo in interphase precipitation behavior is not fully understood. In this contribution, interphase precipitation behavior in a series of Ti-Mo-bearing low carbon steels is systematically studied, and the role of Mo in interphase precipitates and its coarsening behavior is revisited. It is found that (Ti, Mo)C precipitates instead of TiC are formed in the Mo-containing alloys, and the average site fraction of Mo in (Ti, Mo)C is almost independent of the bulk Mo content. Moreover, the number density of interphase precipitates can be substantially enhanced by a minor addition of Mo, albeit it does not further rise with increasing the bulk Mo content. This is because the Mo fraction in (Ti, Mo)C rather than the bulk Mo content governs the driving force for precipitation nucleation and the interfacial energy of the (Ti, Mo)C/α and (Ti, Mo)C/γ interfaces. In addition to the reduced interfacial energy, decrease of Ti trans-interface diffusivity has been identified as another key reason for the enhanced carbide coarsening resistance in Mo-containing alloys.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Novel Aerospace Material
The Structure and Photocatalytic Function of Hydroxyapatite with Doped Ti (IV) Ion
No full textP(論文)Hydroxyapatite (HAp) has a molecular structure in which Ca^, PO_4^ and OH^- are major components. When hydroxyapatite is formed the Ca^, PO_4^ and OH^- ions can be substituted with other specific ions. When a specific ion is purposely replaced in the forming hydroxyapatite crystal, there is a possibility that the new hydroxyapatite might demonstrate properties that could be attributed to the substituted ion. This change in hydroxyapatite properties has been demonstrated when F^- has been substituted for OH^-, F^- has significant acid resistance. The acid resistance property of F^- was observed when F^- was substituted for OH^- in hydroxyapatite. Therefore, the author performed the following experiment : The first portion of the experiment was the synthesis of HAp using the coprecipitation method substituting Ti^ for Ca^. The Ti^ was doped to the Ca^ position in the forming hydroxyapatite crystal. In the next phase of this experiment the author analyzed whether the HAp had obtained photocatalytic function that is a major character of Ti^. HAp using the coprecipitation method was synthesized with different concentrations of Ti^. Respectively the HAp was prepared with Ti^ concentrations of 0.01, 0.005, 0.0025 and 0 moles. The determination of the elementary composition of the synthesized TiHAp was investigated with ICP analysis. The structure of the TiHAp crystal was also investigated by X-ray diffraction. The TiHAp was irradiated by ultraviolet light to determine and measure the presence of photocatalytic function. The formation of radicals and their strength were also measured by ESR spin trapping. A specimen was prepared with 1% TiHAp combined with polypropylene and a second specimen was prepared with 1% TiHAp combined acrylic denture base resins. These specimens were then investigated by a facilitated deterioration exposure test. The photocatalytic function of each specimen was also investigated. The following conclusions of the experiment were obtained : 1. The X-ray diffraction of the TiHAp showed a. reversed correlative phenomenon when anatase dioxide titanium was at 25° (2θ) and the peak strength of HAp was at 26° (2θ) due to the doped Ti^. Therefore, the observed change in the HAp must be a consequence of the doped Ti^ into the HAp molecule. The mole ratio of the Ca/P in the synthetic substance showed that the Ti^ concentration was dependent on the successful doping of Ti^ for Ca^. It was observed that the more successful the dope of Ti^ for Ca^ the mole ratio showed a rectilinear decrease. Therefore, this observation confirmed that Ti^ had replaced Ca^. 2. The OH radical was identified from the post ultraviolet irradiated synthesized substance. The strength of the OH radical increased when the success of the substitution of Ti^ for Ca^ increased. 3. The observation of a clear OH radical signal by ultraviolet irradiation was confirmed from the outer layers of both the polypropylene and acrylic denture base resins that had been combined with 1 % of the synthesized TiHAp. It was observed that there was delayed depletion in the resins that had been combined with the synthesized TiHAp. The results of this experiment provided these conclusions : When a desired concentration of Ti^ has been successfully substituted for Ca^ in a synthesized hydroxyapatite crystal the newly synthesized HAp obtained photocatalytic function that is a special characteristic of titanium.departmental bulletin pape
Inbound and outbound trucks scheduling at crossdocks:
No full textIn today’s customer driven economy, moving products quickly, efficiently, and cost effectively offers crucial advantages to companies. To achieve these goals, more and more companies are finding that cross-docking can play an integral part in their distribution model by partially replacing or complementing existing warehousing facilities. Crossdocking is a material handling and distribution operation, which moves products quickly and directly from inbound trucks (ITs) to outbound trucks (OTs) through the crossdock facility where products are being resorted or consolidated, without being stored or only with a short-term storage, usually within 24 hours or sometimes only within one hour.
This research deals with the scheduling of both ITs and OTs at a crossdocking facility where three objectives are considered: The first objective is to minimize the starting and handling time of all ITs; the second objective is to minimize the total weighted distance of pallets traveled inside the crossdock facility; and the third objective is to minimize the total departure time of all OTs. Multi-objective mixed-integer program formulations are built in order to address the problem. Justification for the use of these objectives in optimizing cross-dock operations is given. Different models are built for three different door layouts at crossdocking facility.
Since the problems are NP-hard, we consider the problem size limitations to obtain an exact solution. In addition, a restriction-approximation approach to solve the models is proposed and the efficiency of our approximation method is proved based on generated data. Finally, numerical examples are provided using the mathematical models built and the approximation approaches. Results for different layouts and scenarios are compared to evaluate the characteristics of different crossdock layouts.M.S.Includes bibliographical references (p. 129-133)by Ti Zhan
Microstructure in rapidly solidified Al-Ti-Si and Al-Ti-Fe alloys
No full textThis thesis was scanned from the print manuscript for digital preservation and is copyright the author.
Researchers can access this thesis by asking their local university, institution or public library to
make a request on their behalf. Monash staff and postgraduate students can use the link in the References field
elliegiulietti/V-Cr-Ti-for-Fusion-Reactors: Vanadium_Alloys (V-Cr-Ti)_for_Fusion_Reactors_AM_Study_Release_v1.0
No full text<h2>Vanadium Alloys (V-Cr-Ti) for Fusion Reactors AM Study</h2>
<p>This repository contains the research and experimental data related to the study on vanadium alloys (specifically V-Cr-Ti alloys, V44 and V1515) for fusion reactors using additive manufacturing (AM) techniques.</p>
<h3>Overview</h3>
<p>Vanadium alloys are potential materials for nuclear fusion reactors due to their structural durability and irradiation resistance. This study focuses on investigating the viability of V-Cr-Ti alloys for AM procedures, aiming to understand crack behaviour and optimise laser parameters for better melt track formation.</p>
<h3>Key Findings</h3>
<ul>
<li>Experimental investigations involved varying laser power and speed on V-Cr-Ti alloys (V44 and V1515) to observe crack behaviour across melt tracks on a laser powder bed fusion (LPBF) machine.</li>
<li>Main types of cracks associated with AM melt tracks were identified, including liquation cracks (LC), solidification cracks (SC), and solid-state cracks (SSC).</li>
<li>Qualitative analysis involved visually determining crack types using optical microscopes and scanning electron microscopy (SEM), while quantitative analysis measured crack density using ImageJ software.</li>
<li>Results indicate that high laser power and low laser speeds result in increased cracking, while low laser power with a mid-range of laser speeds result in less cracking and a more optimal melt track.</li>
<li>An operating window between 60 and 150 W laser power and 850 to 1500 mm/s has been identified, with further studies required for confirmation and comparison to powder processing.</li>
</ul>
<h3>Future Directions</h3>
<ul>
<li>Future studies should focus on comparing data with similar alloys, refining laser parameters, and exploring microstructural properties for deeper insights into crack formation mechanisms.</li>
<li>Sharing of experimental data to facilitate accessibility and reusability for the scientific community.</li>
</ul>
<h3>Dissertation Details</h3>
<p>Dissertation submitted to the University of Sheffield in partial fulfilment of the requirements for the degree of Master of Engineering.
Dissertation title: Vanadium Alloys for Fusion Reactors: Determining their Viability for Additive Manufacturing Procedures.
Author: Ellie Giulietti
Supervisor: Dr Russell Goodall
May 2024</p>
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