David S. Zamar

University of British Columbia | UBC · School of Population and Public Health

Racism continues to drive health disparities between Indigenous and non-Indigenous peoples in Canada. This study focuses on racism experienced by young Indigenous people who have used drugs in British Columbia (BC), and predictors of interpersonal racism. Cedar Project is a community-governed cohort study involving young Indigenous people who use d...

Objectives: Adolescent girls and young women under 25-years (AGYW) account for disproportionate HIV infections in sub-Saharan Africa. Impacts of war in Northern Uganda continue to affect HIV-related health and wellbeing of young people post-conflict. Prevalence and incidence of HIV infection were estimated, and factors associated with HIV prevalen...

Background and objectives: Reducing the maximum red blood cell (RBC) shelf-life is under consideration due to potential negative effects of older blood. An assessment of the impacts of this change on blood supply chain management is evaluated. Materials and methods: We performed a simulation study using data from 2017 to 2018 to estimate the out...

Background and objectives Reconstituted fibrinogen concentrate is considered stable for 8–24 h based on product monographs. Given the long half-life of fibrinogen in vivo (3–4 days), we hypothesized that reconstituted sterile fibrinogen protein would remain stable longer than 8–24 h. Extending the expiry date for reconstituted fibrinogen concentrat...

Background and objectives: Immunoglobulin (Ig) usage has ongoing shortage concerns. Secondary immunodeficiencies (SIDs) account for a major proportion of usage of Igs in Canada. We audited Ig usage in patients with SID at three British Columbia hospitals to determine whether more stringent local guidelines are necessary. Materials and methods: A...

Background From 1986 to 2006, Northern Uganda experienced an atrocious civil war between the Lord's Resistance Army (LRA) and the Ugandan government. Acholi people living in the region continue to be impacted by trauma sequelae of the war and a wide range of daily stressors including poverty, hunger, and high rates of HIV infection. To date, there...

Objectives This study examined associations between childhood maltreatment, colonial harms and sex/drug-related risks for HIV and hepatitis C virus (HCV) infection among young Indigenous people who use drugs. Design The Cedar Project is a cohort involving young Indigenous people who use drugs in British Columbia (BC), Canada. Indigenous collaborat...

Indigenous leaders are gravely concerned over disproportionate representation of Indigenous children in Canada’s child welfare systems. Forced separation from children is deeply traumatizing for mothers and detrimental to the wellbeing of Indigenous families, communities and Nations. This study examined relationships between child apprehension and...

Background The legacy of war in Northern Uganda continues to impact people’s health and wellbeing in the Acholi region. Despite increasing attention to Hepatitis B Virus (HBV) in Uganda and globally, concerns remain that unique drivers of infection, and barriers to screening, and treatment, persist among those affected by conflict. Methods Cango L...

Background Indigenous women involved in survival sex work face multiple layers of discrimination, criminalization and alarming levels of intergenerational and lifetime trauma. This longitudinal study examined historical, structural and interpersonal factors associated with survival sex work involvement among Indigenous women who have used drugs in...

Background Civil war in Northern Uganda resulted in widespread atrocities, human rights violations, and death, and caused millions to flee to internally displaced persons camps. War-related traumas combined with difficulties accessing HIV prevention and health services has led to extreme HIV-related vulnerability among conflict-affected people who...

Background Mental health and wellbeing, including addressing impacts of historical trauma and substance use among young people, has been identified as a key priority by Indigenous communities and leaders across Canada and globally. Yet, research to understand mental health among young Indigenous people who have used drugs is limited. Aims To exami...

Background Traditional key performance indicators (KPIs) for red blood cell (RBC) inventory management such as blood shortage rate (BSR) and outdate rate (ODR) alone are observed to be insensitive for large hospitals, often due to fluctuating demands and rapid turnover. We hypothesized that improvement in complementary KPIs for RBC supply chains, i...

In this paper, the authors have proposed an ensemble Kalman filter based stochastic model predictive control algorithm to determine an optimal control policy at every sampling time instant for a constrained stochastic linear system. To determine an optimal control policy for the constrained linear system affected by random disturbances and measurem...

Background: Young Indigenous people, particularly those involved in the child welfare system, those entrenched in substance use and those living with HIV or hepatitis C, are dying prematurely. We report mortality rates among young Indigenous people who use drugs in British Columbia and explore predictors of mortality over time. Methods: We analy...

The collection of sawmill residues is an important logistic activity for the pulp and paper industry, which uses the biomass as a source of energy. We study a vehicle routing problem for a network composed of a single depot and several sawmills. The sawmills serve as potential suppliers of biomass residues to the depot, which in turn processes and...

The bale collection problem (BCP) appears after harvest operations of agricultural crops. The solution to the BCP is defined by the sequence in which bales, that lie scattered across the field, are collected. This paper presents a constrained k-means algorithm and nearest neighbor approach to the BCP, which minimizes travel time and hence fuel cons...

The collection of sawmill residuals is an important logistic activity for the pulp and paper industry, which use the biomass as a source of energy. We study a vehicle routing problem for a network composed of a single depot and 25 nearby sawmills in the Lower Mainland region of British Columbia, Canada. The sawmills serve as potential suppliers of...

Supply chain optimization for biomass-based power plants is an important research area due to greater emphasis on renewable power energy sources. Biomass supply chain design and operational planning models are often formulated and studied using deterministic mathematical models. While these models are beneficial for making decisions, their applicab...

Supply chain optimization for biomass-based power plants is an important research area due to greater emphasis on renewable power energy sources. This paper develops a robust quantile-based approach for stochastic optimization under uncertainty, which builds upon scenario analysis. We apply our approach to address the problem of analyzing competing...

One of the major challenges facing society is our ability to produce food, energy, fibre and other materials efficiently and sustainably to meet growing resource demands without harming the environment. There is an increasing need, use and reliance on geospatial information in assessing supply-chain uncertainty and industrial production risks. More...

We present a novel forecasting method for generating agricultural crop yield forecasts at the seasonal and regional-scale, integrating agroclimate variables and remotely-sensed indices. The method devises a multivariate statistical model to compute bias and uncertainty in forecasted yield at the Census of Agricultural Region (CAR) scale across the...

An integrated assessment model is being developed and tested to explore possible future trends of Canadian agriculture in response to projected global scenarios in the ecological, economic, and social dimensions. Although many studies suggest more favorable growing conditions for Canada due to rising temperature and CO2 concentration, the agricultu...

Traditional methods of genetic study design and analysis work well under the scenario that a handful of single nucleotide polymorphisms (SNPs) independently contribute to the risk of disease. For complex diseases, susceptibility may be determined not by a single SNP, but rather a complex interplay between SNPs. For large studies involving hundreds...

The epithelial cell-derived protein thymic stromal lymphopoietin stimulates dendritic and mast cells to promote proallergic T(H)2 responses. Studies of transgenic expression of thymic stromal lymphopoietin and its receptor knockout mice have emphasized its critical role in the development of allergic inflammation. Association of genetic variation i...

Asthma, atopy, and related phenotypes are heterogeneous complex traits, with both genetic and environmental risk factors. Extensive research has been conducted and over hundred genes have been associated with asthma and atopy phenotypes, but many of these findings have failed to replicate in subsequent studies. To separate true associations from fa...

Exact inference is based on the conditional distribution of the sufficient statistics for the parameters of interest given the observed values for the remaining sufficient statistics. Exact inference for logistic regression can be problematic when data sets are large and the support of the conditional distribution cannot be represented in memory. A...