Resonant ultrasound spectroscopy applications: Elastic moduli computation with x-ray computed tomography input for irregularly shaped objects.

Resonant ultrasound spectroscopy is a technique that uses a combination of experimentally measured resonant frequencies and physics-based computation of these frequencies to determine the entire set of single crystal elastic moduli of the material. Computation of the resonances is most often accomplished using the Rayleigh-Ritz energy minimization technique, and a basis function that requires sample with canonical geometry, such as a cylinder or a rectangular parallelepiped. Any deviation from canonical geometry can have a significant impact on the calculated resonance frequencies and the inverted elastic moduli. To overcome this limitation, this paper describes an approach that uses x-ray computed tomography data to generate accurate solid part model of components with complex geometry. The part model is then imported into an off-the-shelf finite element method (FEM) software to perform the forward problem. The FEM was combined with surrogate modeling for computation of resonance frequencies of both canonical and non-canonical samples, and ultimately, the inversion of elastic moduli.

Prevalence, temporal course and risk factors for phantom eye symptoms in uveal melanoma.

BACKGROUND: Phantom eye symptoms (PES), particularly phantom visual sensations (PVS) and phantom eye pain (PEP), are common in enucleated patients and can lead to psychological distress. Current cross-sectional studies cannot examine the temporal course of symptoms, nor can they identify dynamic risk factors or consequences of PES. METHODS: Cohort study of 105 enucleated uveal melanoma patients returning self-report questionnaires, within 4 weeks of diagnosis and 6-, 12- and 24-months post-treatment. Questionnaires measuring PVS and PEP symptoms in the week prior to completion, pain severity, Hospital Anxiety and Depression Scale scores and the Functional Assessment of Cancer Therapy scale (FACT-G) measuring quality of life. RESULTS: PVS and PEP emerged after 6 months, were relatively stable over the study and did not remit. PVS showed 6-, 12- and 24-month prevalence rates of 44.6%, 48.2% and 30.2%, and PEP 16.1%, 18.4% and 17.5% respectively. PVS were generally elementary, with only 10-15% of the total cohort experiencing complex sensations. PEP was generally neither prolonged nor intense, except in a small proportion. PVS and PEP were showed moderate associations but did not predict each other prospectively. Anxiety within 4 weeks of diagnosis was a risk factor for the initiation of PEP. Neither PVS nor PEP prospectively predicted anxiety, depression or quality of life. CONCLUSIONS: PES were prevalent and non-remitting, beginning within 6 months of enucleation. PVS and PEP may not represent symptoms of a coherent syndrome. We discuss findings with reference to theories of phantom sensations, and directions for clinical practise and research.

Direct Measurement of the Spectral Structure of Cosmic-Ray Electrons+Positrons in the TeV Region with CALET on the International Space Station.

Detailed measurements of the spectral structure of cosmic-ray electrons and positrons from 10.6 GeV to 7.5 TeV are presented from over 7 years of observations with the CALorimetric Electron Telescope (CALET) on the International Space Station. The instrument, consisting of a charge detector, an imaging calorimeter, and a total absorption calorimeter with a total depth of 30 radiation lengths at normal incidence and a fine shower imaging capability, is optimized to measure the all-electron spectrum well into the TeV region. Because of the excellent energy resolution (a few percent above 10 GeV) and the outstanding e/p separation (10^{5}), CALET provides optimal performance for a detailed search of structures in the energy spectrum. The analysis uses data up to the end of 2022, and the statistics of observed electron candidates has increased more than 3 times since the last publication in 2018. By adopting an updated boosted decision tree analysis, a sufficient proton rejection power up to 7.5 TeV is achieved, with a residual proton contamination less than 10%. The observed energy spectrum becomes gradually harder in the lower energy region from around 30 GeV, consistently with AMS-02, but from 300 to 600 GeV it is considerably softer than the spectra measured by DAMPE and Fermi-LAT. At high energies, the spectrum presents a sharp break around 1 TeV, with a spectral index change from -3.15 to -3.91, and a broken power law fitting the data in the energy range from 30 GeV to 4.8 TeV better than a single power law with 6.9 sigma significance, which is compatible with the DAMPE results. The break is consistent with the expected effects of radiation loss during the propagation from distant sources (except the highest energy bin). We have fitted the spectrum with a model consistent with the positron flux measured by AMS-02 below 1 TeV and interpreted the electron+positron spectrum with possible contributions from pulsars and nearby sources. Above 4.8 TeV, a possible contribution from known nearby supernova remnants, including Vela, is addressed by an event-by-event analysis providing a higher proton-rejection power than a purely statistical analysis.

Erratum: Charge-Sign Dependent Cosmic-Ray Modulation Observed with the Calorimetric Electron Telescope on the International Space Station [Phys. Rev. Lett. 130, 211001 (2023)].

This corrects the article DOI: 10.1103/PhysRevLett.130.211001.

Rain, recreation and risk: Human activity and ecological disturbance create seasonal risk landscapes for the prey of an ambush predator.

Predation risk and prey responses exhibit fluctuations in space and time. Seasonal ecological disturbances can alter landscape structure and permeability to influence predator activity and efficacy, creating predictable patterns of risk for prey (seasonal risk landscapes). This may create corresponding seasonal shifts in antipredator behaviour, mediated by species ecology and trade-offs between risk and resources. Yet, how human recreation interacts with seasonal risk landscapes and antipredator behaviour remains understudied. In South Florida, we investigated the impact of a seasonal ecological disturbance, specifically flooding, which is inversely related to human activity, on interactions between Florida panthers (Puma concolor coryi) and white-tailed deer (Odocoileus virginianus). We hypothesized that human activity and ecological disturbances would interact with panther-deer ecology, resulting in the emergence of two distinct seasonal landscapes of predation risk and the corresponding antipredator responses. We conducted camera trap surveys across southwestern Florida to collect detection data on humans, panthers and deer. We analysed the influence of human site use and flooding on deer and panther detection probability, co-occurrence and diel activity during the flooded and dry seasons. Flooding led to decreased panther detections and increased deer detections, resulting in reduced deer-panther co-occurrence during the flooded season. Panthers exhibited increased nocturnality and reduced diel activity overlap with deer in areas with higher human activity. Supporting our hypothesis, panthers' avoidance of human recreation and flooding created distinct risk schedules for deer, driving their antipredator behaviour. Deer utilized flooded areas to spatially offset predation risk during the flooded season while increasing diurnal activity in response to human recreation during the dry season. We highlight the importance of understanding how competing risks and ecological disturbances influence predator and prey behaviour, leading to the generation of seasonal risk landscapes and antipredator responses. We emphasize the role of cyclical ecological disturbances in shaping dynamic predator-prey interactions. Furthermore, we highlight how human recreation may function as a 'temporal human shield,' altering seasonal risk landscapes and antipredator responses to reduce encounter rates between predators and prey.

Charge-Sign Dependent Cosmic-Ray Modulation Observed with the Calorimetric Electron Telescope on the International Space Station.

We present the observation of a charge-sign dependent solar modulation of galactic cosmic rays (GCRs) with the Calorimetric Electron Telescope onboard the International Space Station over 6 yr, corresponding to the positive polarity of the solar magnetic field. The observed variation of proton count rate is consistent with the neutron monitor count rate, validating our methods for determining the proton count rate. It is observed by the Calorimetric Electron Telescope that both GCR electron and proton count rates at the same average rigidity vary in anticorrelation with the tilt angle of the heliospheric current sheet, while the amplitude of the variation is significantly larger in the electron count rate than in the proton count rate. We show that this observed charge-sign dependence is reproduced by a numerical "drift model" of the GCR transport in the heliosphere. This is a clear signature of the drift effect on the long-term solar modulation observed with a single detector.

Direct Measurement of the Cosmic-Ray Helium Spectrum from 40 GeV to 250 TeV with the Calorimetric Electron Telescope on the International Space Station.

We present the results of a direct measurement of the cosmic-ray helium spectrum with the CALET instrument in operation on the International Space Station since 2015. The observation period covered by this analysis spans from October 13, 2015, to April 30, 2022 (2392 days). The very wide dynamic range of CALET allowed for the collection of helium data over a large energy interval, from ∼40 GeV to ∼250 TeV, for the first time with a single instrument in low Earth orbit. The measured spectrum shows evidence of a deviation of the flux from a single power law by more than 8σ with a progressive spectral hardening from a few hundred GeV to a few tens of TeV. This result is consistent with the data reported by space instruments including PAMELA, AMS-02, and DAMPE and balloon instruments including CREAM. At higher energy we report the onset of a softening of the helium spectrum around 30 TeV (total kinetic energy). Though affected by large uncertainties in the highest energy bins, the observation of a flux reduction turns out to be consistent with the most recent results of DAMPE. A double broken power law is found to fit simultaneously both spectral features: the hardening (at lower energy) and the softening (at higher energy). A measurement of the proton to helium flux ratio in the energy range from 60 GeV/n to about 60 TeV/n is also presented, using the CALET proton flux recently updated with higher statistics.

Fear of cancer recurrence and adverse cancer treatment outcomes: predicting 2- to 5-year fear of recurrence from post-treatment symptoms and functional problems in uveal melanoma survivors.

OBJECTIVE: The fear of cancer recurrence (FCR) in later survivorship can lead to poorer mental health, quality of life and physical and functional recovery. Later-occurring FCR may be a consequence of late-emerging physical symptoms and functional problems from cancer or its treatment. Based on the self-regulation model, we predicted that persistent or escalating symptoms and functional problems would prospectively predict FCR observed 2-5 years after diagnosis and treatment. METHODS: This is a five-year study of 708 uveal melanoma (UM) patients, measuring self-reported visual and ocular symptoms, functional problems and FCR at 6, 12, 24, 36, 48 and 60 months post-diagnosis. A mixed measures design over four levels with observations staggered to represent prospective prediction. Criterion variables were FCR at 24, 36, 48 and 60 months. Predictors were symptom and function scores measured at the previous two observations to FCR. Controls were FCR measured at the previous observation to the criterion FCR measure and demographic, clinical and treatment variables. RESULTS: Linear mixed modelling showed that FCR was uniquely predicted by enduring symptoms, those that emerged two observations previously, but not symptoms arising at the previous observation. FCR was predicted by functional problems, which emerged in the observation prior to FCR, but not the observation previous to that. CONCLUSIONS: Persistent or emerging post-treatment symptoms and functional limitations are probable risk factors for late-occurring FCR in UM survivors. IMPLICATIONS FOR CANCER SURVIVORS: Monitoring symptoms and functional limitations assists in identifying at-risk survivors and targeting preventive interventions. Self-regulation theory suggests that helping survivors to more realistically appraise symptoms and functional problems may prevent FCR.

Developing Health Care Faculty to Address the Needs of North Carolina's Diverse Populations.

Addressing community needs improves population health and the well-being of health care providers. The development of the health care workforce requires faculty to address the needs of North Carolina's diverse and rural populations. This can be best accomplished by building interdisciplinary and cross-functional service-learning experiences and developing community-academic partnerships and coalitions.

Observation of Spectral Structures in the Flux of Cosmic-Ray Protons from 50 GeV to 60 TeV with the Calorimetric Electron Telescope on the International Space Station.

A precise measurement of the cosmic-ray proton spectrum with the Calorimetric Electron Telescope (CALET) is presented in the energy interval from 50 GeV to 60 TeV, and the observation of a softening of the spectrum above 10 TeV is reported. The analysis is based on the data collected during ∼6.2 years of smooth operations aboard the International Space Station and covers a broader energy range with respect to the previous proton flux measurement by CALET, with an increase of the available statistics by a factor of ∼2.2. Above a few hundred GeV we confirm our previous observation of a progressive spectral hardening with a higher significance (more than 20 sigma). In the multi-TeV region we observe a second spectral feature with a softening around 10 TeV and a spectral index change from -2.6 to -2.9 consistently, within the errors, with the shape of the spectrum reported by DAMPE. We apply a simultaneous fit of the proton differential spectrum which well reproduces the gradual change of the spectral index encompassing the lower energy power-law regime and the two spectral features observed at higher energies.

Direct Measurement of the Nickel Spectrum in Cosmic Rays in the Energy Range from 8.8 GeV/n to 240 GeV/n with CALET on the International Space Station.

The relative abundance of cosmic ray nickel nuclei with respect to iron is by far larger than for all other transiron elements; therefore it provides a favorable opportunity for a low background measurement of its spectrum. Since nickel, as well as iron, is one of the most stable nuclei, the nickel energy spectrum and its relative abundance with respect to iron provide important information to estimate the abundances at the cosmic ray source and to model the Galactic propagation of heavy nuclei. However, only a few direct measurements of cosmic-ray nickel at energy larger than ∼3 GeV/n are available at present in the literature, and they are affected by strong limitations in both energy reach and statistics. In this Letter, we present a measurement of the differential energy spectrum of nickel in the energy range from 8.8 to 240 GeV/n, carried out with unprecedented precision by the Calorimetric Electron Telescope (CALET) in operation on the International Space Station since 2015. The CALET instrument can identify individual nuclear species via a measurement of their electric charge with a dynamic range extending far beyond iron (up to atomic number Z=40). The particle's energy is measured by a homogeneous calorimeter (1.2 proton interaction lengths, 27 radiation lengths) preceded by a thin imaging section (3 radiation lengths) providing tracking and energy sampling. This Letter follows our previous measurement of the iron spectrum [1O. Adriani et al. (CALET Collaboration), Phys. Rev. Lett. 126, 241101 (2021).PRLTAO0031-900710.1103/PhysRevLett.126.241101], and it extends our investigation on the energy dependence of the spectral index of heavy elements. It reports the analysis of nickel data collected from November 2015 to May 2021 and a detailed assessment of the systematic uncertainties. In the region from 20 to 240 GeV/n our present data are compatible within the errors with a single power law with spectral index -2.51±0.07.

Cosmic-Ray Boron Flux Measured from 8.4 GeV/n to 3.8 TeV/n with the Calorimetric Electron Telescope on the International Space Station.

We present the measurement of the energy dependence of the boron flux in cosmic rays and its ratio to the carbon flux in an energy interval from 8.4 GeV/n to 3.8 TeV/n based on the data collected by the Calorimetric Electron Telescope (CALET) during ∼6.4 yr of operation on the International Space Station. An update of the energy spectrum of carbon is also presented with an increase in statistics over our previous measurement. The observed boron flux shows a spectral hardening at the same transition energy E_{0}∼200 GeV/n of the C spectrum, though B and C fluxes have different energy dependences. The spectral index of the B spectrum is found to be γ=-3.047±0.024 in the interval 25

Prediction of all-cause mortality from 24 month trajectories in patient-reported psychological, clinical and quality of life outcomes in uveal melanoma patients.

A number of patient-reported outcomes (PROs) predict increased mortality after primary cancer treatment. Studies, though, are sometimes affected by methodological limitations. They often use control variables that poorly predict life expectancy, examine only one or two PROs thus not controlling potential confounding by unmeasured PROs, and observe PROs at only a single point in time. To predict all-cause mortality, this study used control variables affording good estimates of life expectancy, conducted multivariate analyses of multiple PROs to identify independent predictors, and monitored PROs two years after diagnosis. We recruited a consecutive sample of 824 patients with uveal melanoma between April 2008 and December 2014. PROs were variables shown to predict mortality in previous studies; anxiety, depression, visual and ocular symptoms, visual function impairment, worry about cancer recurrence, and physical, emotional, social and functional quality of life (QoL), measured 6, 12 and 24 months after diagnosis. We conducted Cox regression analyses with a census date of December 2018. Covariates were age, gender, marital and employment status, self-reported co-morbidities, tumor diameter and thickness, treatment modality and chromosome 3 mutation status, the latter a genetic mutation strongly associated with mortality. Single predictor analyses (with covariates), showed 6-month depression and poorer functional QoL predicting mortality, as did 6-12 month increases in anxiety and 6-12 month decreases in physical and functional QoL. Multivariate analyses using all PROs showed independent prediction by 6-month depression and decreasing QoL over 6-12 months and 12-24 months. Elevated depression scores six months post-diagnosis constituted an increased mortality risk. Early intervention for depressive symptoms may reduce mortality.

Is accurate routine cancer prognostication psychologically harmful? 5-year outcomes of life expectancy prognostication in uveal melanoma survivors.

PURPOSE: Prognostication in cancer is growing in importance as increasingly accurate tools are developed. Prognostic accuracy intensifies ethical concerns that a poor prognosis could be psychologically harmful to survivors. Uveal melanoma (UM) prognostication allows survivors to be reliably told that life expectancy is either normal (good prognosis) or severely curtailed because of metastatic disease (poor prognosis). Treatment cannot change life expectancy. To identify whether prognosis is associated with psychological harm, we compared harm in UM survivors with good and poor prognoses and those who declined testing and compared these outcomes to general population norms. METHODS: Non-randomized 5-year study of a consecutive series of 708 UM survivors (51.6% male, mean age 69.03, SD=12.12) with observations at 6, 12, 24, 36, 48 and 60 months. We operationalized psychological harm as anxiety and depression symptoms, worry about cancer recurrence (WREC) and poor quality of life (QoL). RESULTS: Compared to other groups, survivors with poor prognoses showed initially elevated anxiety and depression and consistently elevated worry about local or distant recurrence over 5 years. Good prognoses were not associated with outcomes. Generally, no prognostic groups reported anxiety, depression and WREC or QoL scores that exceeded general population norms. CONCLUSIONS: Using a large sample, we found that harm accruing from a poor prognosis was statistically significant over 5 years, but did not exceed general non-cancer population norms. IMPLICATIONS FOR CANCER SURVIVORS: Survivors desire prognostic information. At a population level, we do not believe that our findings show sufficiently strong links between prognostication outcome and psychological harm to deny patients the option of knowing their prognosis. Nonetheless, it is important that patients are informed of potential adverse psychological consequences of a poor prognosis.

Measurement of the Iron Spectrum in Cosmic Rays from 10 GeV/n to 2.0 TeV/n with the Calorimetric Electron Telescope on the International Space Station.

The Calorimetric Electron Telescope (CALET), in operation on the International Space Station since 2015, collected a large sample of cosmic-ray iron over a wide energy interval. In this Letter a measurement of the iron spectrum is presented in the range of kinetic energy per nucleon from 10 GeV/n to 2.0 TeV/n allowing the inclusion of iron in the list of elements studied with unprecedented precision by space-borne instruments. The measurement is based on observations carried out from January 2016 to May 2020. The CALET instrument can identify individual nuclear species via a measurement of their electric charge with a dynamic range extending far beyond iron (up to atomic number Z=40). The energy is measured by a homogeneous calorimeter with a total equivalent thickness of 1.2 proton interaction lengths preceded by a thin (3 radiation lengths) imaging section providing tracking and energy sampling. The analysis of the data and the detailed assessment of systematic uncertainties are described and results are compared with the findings of previous experiments. The observed differential spectrum is consistent within the errors with previous experiments. In the region from 50 GeV/n to 2 TeV/n our present data are compatible with a single power law with spectral index -2.60±0.03.

County-level correlates of dental service utilization for low income pregnant women. Ecologic study of the North Carolina Medicaid for Pregnant Women (MPW) program.

BACKGROUND: Dental care utilization for low income pregnant women is met with challenges in the traditional dentist-centered model of care. County-level measures provide insights for policy and roles for stakeholders that extend beyond the dentist-patient relationship. We examined county-level data to generate hypotheses about factors that influence utilization of dental services in North Carolina's Medicaid for Pregnant Women (MPW) program. METHODS: County-level Medicaid utilization data for dental services for 2014-2016 were pooled to get mean county estimates of dental utilization in the MPW program. Descriptive statistics and multivariate regression models of dental utilization and county-level measures are presented. Data used were collected by NC Child and the Robert Wood Johnson Foundation's County Health Rankings Reports. USDA Economic Research Service data were used to categorize counties in terms of Farming, Recreation, Persistent Poverty, and metro/non-metro status using Rural Urban Continuum Codes. RESULTS: Dental utilization ranged from 1-26% with a median of 8.5% across the 100 counties of North Carolina. Strong patterns linking utilization of dental services in the MPW program to contextual social measures of well-being emerged, specifically, increased reporting of child abuse and neglect, elevated infant mortality, poor quality of life, and worse ranking in years of potential life lost. Counties with persistent poverty had lower rates of dental utilization. CONCLUSIONS: Utilization of dental services in the MPW program is generally low. Patterns identify the potential for enhancing community-clinical linkages to improve birth outcomes and care coordination for pregnant women to enhance dental utilization in this population. Dental coverage in the Medicaid program in most states is administered separately from medical coverage. The separation of the funding mechanisms adds a further layer of complexity to care integration. Efforts to enhance dental care for pregnant women in the Medicaid program may benefit from policy that aligns incentives for care coordination within the community. Policy that extends the window of eligibility for dental benefits to 24 months after the birth of the child will help women complete the dental treatment that is needed. This also leverages the value of care coordination for community stakeholders from diverse child health sectors.

Resilience, Self-compassion, and Mental Health Outcomes: Rebuilding Eastern North Carolina After Natural Disasters.

Natural disasters have occurred more frequently in Eastern North Carolina in recent years. Evidence supports that repeated exposure to natural disasters may have lasting mental health impacts among vulnerable populations. Greater access to mental health services may aid in ensuring equitable access to needed care and promote resilience.

Predictors of long-term anxiety and depression in uveal melanoma survivors: A cross-lagged five-year analysis.

OBJECTIVE: Cancer survivors commonly experience long-term anxiety and depression. Anxiety and depression might result from problems emerging during survivorship rather than illness and treatment. This study tested three potential causal paths: (a) concerns about physical symptoms and functional problems and fear of cancer recurrence (FCR) arising during survivorship directly cause anxiety and depression, (b) an indirect path whereby FCR mediates effects of concerns about physical symptoms and functional problems on anxiety and depression, and (c) a reciprocal path whereby anxiety and depression cause concerns about physical symptoms and functional problems and FCR, which exacerbate later anxiety and depression. METHODS: Sample of 453 uveal melanoma survivors who completed observations 6-, 12-, 24-, 36-, 48- and 60-months post-diagnosis and did not miss two consecutive observations. Cross-lagged analyses were conducted to predict Hospital Anxiety and Depression Scale subscale scores. Symptoms and functional problems were measured using the EORTC OPT 30 scale, and FCR operationalised by the EORTC OPT 30 worry about recurrence scale. Covariates were age, gender, treatment modality, and visual acuity of the fellow eye and chromosome-3 status (which accurately predicts 10-year survival), worry and anxiety or depression. RESULTS: All paths received some support, although the indirect path emerged only for anxiety in females. Concerns about physical symptoms, functional problems, and FCR originated in survivorship and appeared to both influence and be influenced by anxiety and depression. CONCLUSIONS: Findings emphasise the importance of actively monitoring survivors to prevent, detect, and intervene in the development of anxiety and depression during survivorship.

People with obsessive-compulsive disorder often remain symptomatic following psychological treatment: A clinical significance analysis of manualised psychological interventions.

BACKGROUND: Previous meta-analyses conclude that efficacious psychological treatments for obsessive-compulsive disorder (OCD) exist. However, determining the efficacy of psychological treatments requires multiple forms of assessment. We conducted an individual patient data meta-analysis of randomised controlled trials (RCTs) of manualised psychological therapy for adults with OCD. METHODS: Four electronic databases were searched from their inception until July 2019. IPD were available for 24 (n = 1626) of 43 (n = 2455) eligible RCTs. Treatment efficacy was evaluated using clinical significance analyses (using standardised Jacobson methodology) and standardised mean difference within-group effect-size analyses. Outcomes were Yale-Brown Obsessive Compulsive Scale (Y-BOCS) scores at post-treatment and follow-up. RESULTS: At follow-up, large within-group effect sizes were found for treated patients (g = 1.45) and controls (g = 0.90). Treated patients were significantly more likely than controls to recover, but recovery rates were low; post-intervention, only 32% of treated patients and 3% of controls recovered; rising to 38% and 21% respectively at follow-up. Regardless of allocation, only 20% of patients were asymptomatic at follow-up. Individual cognitive therapy (CT) was most efficacious, followed by group CT plus exposure and response prevention. Self-help interventions were generally less efficacious than face-to-face approaches. LIMITATIONS: Data were analysed from 24 of the 43 eligible RCTs. We were unable to consider the long-term efficacy of treatments because only two RCTs provided long-term (> 12 month) follow-up data. CONCLUSION: Almost 80% of treated patients remain symptomatic. The efficacy of psychological interventions for patients with OCD must be enhanced.

Trajectories of Homeless Shelter Utilization in the At Home/Chez Soi Trial of Housing First.

OBJECTIVE: Studies have shown that Housing First, a recovery-oriented housing intervention, is effective in reducing service utilization among homeless individuals with mental illness, but less is known about how Housing First affects patterns of service use over time and about characteristics associated with various utilization trajectories. This analysis aimed to explore latent class trajectories of shelter utilization in a randomized controlled trial of Housing First conducted across five Canadian cities. METHODS: Data from the At Home/Chez Soi trial were analyzed (N=2,058). Latent class growth analysis was performed using days of shelter utilization to identify trajectories over 24 months. Multinomial logistic regression was used to determine which baseline variables, including treatment group, could predict class membership. RESULTS: Four shelter use trajectories were identified: consistently low (N=1,631, 79%); mostly low (N=120, 6%); early temporary increase (N=179, 9%); and higher use, late temporary increase (N=128, 6%). Treatment group was a significant predictor of class membership. Those enrolled in Housing First had lower odds of experiencing higher shelter use trajectories (mostly low: odds ratio [OR]=0.50, 95% confidence interval [CI]=0.34-0.72; early temporary increase: OR=0.21, 95% CI=0.15-0.31; higher use, late temporary increase: OR=0.14, 95% CI=0.09-0.22). Other variables associated with trajectory classes included older age and longer time homeless, both of which were associated with higher shelter use. CONCLUSIONS: Several participant characteristics were associated with different shelter use patterns. Knowledge of variables associated with more favorable trajectories may help to inform service planning and contribute to modeling efforts for homelessness.