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The aim of this research is to identify the prosthetic foot that results in improved walking performance when individuals with lower limb amputation carry infants, toddlers, or other loads.
The natural lower limbs provide important biomechanical functions such as body weight support, forward propulsion, and balance control during ambulation. When the loads borne by the lower limbs change, lower limb muscle activation responds accordingly to enable seamless continuation of biomechanical function. These loads can change suddenly, such as when carrying an infant, toddler, or other load like a heavy backpack. For individuals with a lower limb amputation, these sudden changes to weight-bearing loads can be problematic because they can negatively impact walking performance. One reason walking performance may suffer is that the properties of most prosthetic limbs, such as their stiffness, are constant and do not change to suit varying load conditions. Another reason is that the most widely prescribed prosthetic feet do not have motors, sensors, or brain-like controllers that act to replace the neuromuscular system of the amputated limb. Regardless of the reason, no evidence exists to guide prescription practice for veterans who walk with a prosthesis and experience sudden load changes.
The aim of this research is to identify the prosthetic foot that results in improved walking performance when individuals with lower limb amputation carry infants, toddlers, or other loads. The investigators will conduct a human subject experiment with help of twenty individuals with below-knee amputations. Study participants will walk on a treadmill with no added load and four added load conditions using a weighted pack (13.6 kg or ~30 lbs) to simulate an infant, toddler, or other load. The four conditions include the pack strapped to their front, their back, and carried with their arms on the intact limb side and the prosthetic limb side. Each participant will wear a usual prosthetic foot, this same foot with a heel-stiffening wedge, the same prosthetic foot but one category stiffness higher, a new-to-market dual keel prosthetic foot intended for load carrying situations, and a powered ankle foot prosthesis. The results from these experiments will aid clinicians in specifying the best prosthesis for individuals with lower limb amputations who frequently carry infants, toddlers, or other loads.
For individuals who wear a lower limb prosthesis while carrying infants, toddlers, or other loads, this research will provide evidence to support prosthesis prescription practice that reduces undesirable compensatory responses to load carriage. The objective is to help clinicians select among currently available solutions to enable individuals with lower limb loss to achieve their life and work goals.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| No added load | Experimental | Study participants will walk with no added load. |
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| Anterior added load | Experimental | Study participants will walk with 13.6 kg (30 lbs) of added load on their anterior side. |
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| Posterior added load | Experimental | Study participants will walk with 13.6 kg (30 lbs) of added load on their posterior side. |
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| Intact-side added load | Experimental | Study participants will walk with 13.6 kg (30 lbs) of added load on their intact side. |
| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Standard-of-care prosthetic foot | Device | Widely prescribed prosthetic foot of stiffness category appropriate to the participant's body weight and activity level. |
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| Measure | Description | Time Frame |
|---|---|---|
| Vertical Ground Reaction Force Impulse (Normalized) | A measure of body support. Normalized by body mass, including the mass of the load when applicable. | During study visit (approximately 3 hours) |
| Anterior Ground Reaction Force Impulse (Normalized) | A measure of body forward propulsion. Normalized by body mass, including the mass of the load when applicable. | During study visit (approximately 3 hours) |
| Peak-to-peak Range of Sagittal Plane Whole-body Angular Momentum (Normalized) | A measure of balance control primarily for anterior and posterior added load conditions. Normalized by body mass (kg) including the mass of the load when applicable, body height (m), and [gravity*body height]^0.5 (m/s) resulting in a unitless number. | During study visit (approximately 3 hours) |
| Peak-to-peak Range of Coronal Plane Whole-body Angular Momentum (Normalized) | A measure of balance control primarily for intact-side added load conditions. Normalized by body mass (kg) including the mass of the load when applicable, body height (m), and [gravity*body height]^0.5 (m/s) resulting in a unitless number. | During study visit (approximately 3 hours) |
| Net Positive Ankle Joint Mechanical Work Over the Prosthetic Limb Gait Cycle (Normalized) | Positive ankle joint mechanical work over the prosthetic limb gait cycle is a measure of propulsion capability. A prosthetic foot with greater propulsion capability may enhance gait efficiency during everyday ambulation. Normalized to body mass and the added load mass when applicable. | During study visit (approximately 3 hours) |
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Inclusion Criteria:
Exclusion Criteria:
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| Name | Affiliation | Role |
|---|---|---|
| Glenn Klute, PhD | VA Puget Sound Care System | Principal Investigator |
| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| VA Puget Sound Health Care System Seattle Division | Seattle | Washington | 98108 | United States |
A de-identified, anonymized dataset in machine-readable format will be created and shared for all individual participant data (IPD) that underlie results in a publication. The investigators will follow 164.514(a) of the HIPAA Privacy Rule for de-identification of IPD.
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Within six months after publication of final study findings.
Open-source data repository (e.g., PubMed Central)
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One enrolled participant decided they were no longer interested in participating after the first visit (alignment and acclimation) but before the second visit (randomization).
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| ID | Title | Description |
|---|---|---|
| FG000 | Individuals With Lower Limb Amputation | In this cross-over study, all subjects were asked to with no added load and four added load conditions using a weighted pack (13.6 kg or ~30 lbs) to simulate an infant, toddler, or other load. The four conditions include the pack strapped to their front (anterior), their back (posterior), and carried with their arms on the intact limb side and the prosthetic limb side. The load conditions were presented in block randomized order. While performing each of these activities, the participant wore five different prosthetic feet. These prosthetic feet included a standard-of-care prosthetic foot, this same prosthetic foot with a heel-stiffening wedge, this same prosthetic foot but one category stiffer, a dual keel prosthetic foot intended for load carriage applications, and a powered ankle-foot purported to adapt to changing loads. The prosthetic feet were worn in randomized order and the subject was blinded to the study foot using a sock and foot cover when possible (wearing a powered ankle-foot is obvious to the participant). The study was conducted over two visits with overnight rest in between each visit. During the first study visit, each study foot was aligned to the participant's prosthesis and wore each for at least 15 minutes. During the second study visit, the participant walked wearing each of the five different study feet while performing each of the five different load conditions. |
| Title | Milestones | Reasons Not Completed | |||||
|---|---|---|---|---|---|---|---|
| Overall Study |
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| Type | Includes Protocol | Includes SAP | Includes ICF | Document Label | Document Date | Document Uploaded Date | Document File Name |
|---|---|---|---|---|---|---|---|
| Prot | Yes | No | No | Study Protocol | Oct 14, 2021 | Dec 18, 2025 |
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This study will employ a within-subject experimental design. Each participant will wear, in randomized order, a standard-of-care prosthetic foot, this same prosthetic foot with a heel-stiffening wedge, this same prosthetic foot but one category stiffer, a dual keel prosthetic foot intended for load carriage applications, and a powered ankle-foot purported to adapt to changing loads. All study prostheses are commercially available. Each participant, wearing each of the study prostheses, will walk overground with no added load and four added load conditions of 13.6 kg: anterior, posterior, intact-side carry, and prosthetic-side carry. The load condition will be presented in block randomized order.
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A sock and foot cover to blind the participants to the study prostheses when possible (use of the powered ankle-foot will be obvious).
| Prosthetic-side added load | Experimental | Study participants will walk with 13.6 kg (30 lbs) of added load on their prosthetic side. |
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| Standard-of-care prosthetic foot with heel-stiffening wedge | Device | Widely prescribed prosthetic foot with a wedge inserted between the heel and foot keels intended to stiffen the behavior of the heel. |
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| Standard-of-care prosthetic foot of one category greater stiffness | Device | Widely prescribed prosthetic foot of one stiffness category greater than usually prescribed based on the participant's body weight and activity level. |
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| Dual keel prosthetic foot | Device | A prosthetic foot with two forefoot keels intended for load carriage applications. |
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| Powered ankle-foot | Device | A powered prosthetic ankle-foot. |
|
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| **Standard-of-care prosthetic foot |
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| Walking with no added load |
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| Walking with anterior load |
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| Walking with posterior side |
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| Walking with load on prosthetic side |
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| Walking with load on intact side |
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| **Standard-of-care prosthetic foot of one category greater stiffness |
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| Walking with no added load |
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| Walking with anterior load |
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| Walking with posterior load |
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| Walking with load on prosthetic side |
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| Walking with load on intact side |
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| **Standard-of-care prosthetic foot with heel-stiffening wedge |
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| Walking with no added load |
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| Walking with anterior load |
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| Walking with posterior load |
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| Walking with load on prosthetic side |
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| Walking with load on intact side |
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| **Dual keel prosthetic foot |
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| Walking with no added load |
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| Walking with anterior load |
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| Walking with posterior load |
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| Walking with load on prosthetic side |
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| Walking with load on intact side |
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| **Powered ankle-foot |
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| Walking with no added load |
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| Walking with anterior load |
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| Walking with posterior load |
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| Walking with load on prosthetic side |
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| Walking with load on intact side |
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| COMPLETED |
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| NOT COMPLETED |
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| ID | Title | Description |
|---|---|---|
| BG000 | Individuals With Lower Limb Amputation | In this cross-over study, all subjects were asked to with no added load and four added load conditions using a weighted pack (13.6 kg or ~30 lbs) to simulate an infant, toddler, or other load. The four conditions include the pack strapped to their front (anterior), their back (posterior), and carried with their arms on the intact limb side and the prosthetic limb side. The load conditions were presented in block randomized order. While performing each of these activities, the participant wore five different prosthetic feet. These prosthetic feet included a standard-of-care prosthetic foot, this same prosthetic foot with a heel-stiffening wedge, this same prosthetic foot but one category stiffer, a dual keel prosthetic foot intended for load carriage applications, and a powered ankle-foot purported to adapt to changing loads. The prosthetic feet were worn in randomized order and the subject was blinded to the study foot using a sock and foot cover when possible (wearing a powered ankle-foot is obvious to the participant). The study was conducted over two visits with overnight rest in between each visit. During the first study visit, each study foot was aligned to the participant's prosthesis and wore each for at least 15 minutes. During the second study visit, the participant walked wearing each of the five different study feet while performing each of the five different load conditions. |
| Units | Counts |
|---|---|
| Participants |
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| Title | Description | Population Description | Parameter Type | Dispersion Type | Unit of Measure | Calculate Percentage | Denominator Units Selected | Denominators | Classes | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Age, Continuous | Mean | Standard Deviation | years |
| |||||||||||||||||
| Sex: Female, Male | Count of Participants | Participants |
| ||||||||||||||||||
| Race (NIH/OMB) | Count of Participants | Participants | No |
| |||||||||||||||||
| Ethnicity (NIH/OMB) | Count of Participants | Participants | No |
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| Type | Title | Description | Population Description | Reporting Status | Anticipated Posting Date | Parameter Type | Dispersion Type | Unit of Measure | Calculate Percentage | Time Frame | Units Analyzed | Denominator Units Selected | Arm/Group Information | Denominators | Classes | Analyses | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Primary | Vertical Ground Reaction Force Impulse (Normalized) | A measure of body support. Normalized by body mass, including the mass of the load when applicable. | Posted | Mean | Standard Error | Newtons*seconds/kg | During study visit (approximately 3 hours) |
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| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Primary | Anterior Ground Reaction Force Impulse (Normalized) | A measure of body forward propulsion. Normalized by body mass, including the mass of the load when applicable. | Posted | Mean | Standard Error | Newtons*seconds/kg | During study visit (approximately 3 hours) |
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Primary | Peak-to-peak Range of Sagittal Plane Whole-body Angular Momentum (Normalized) | A measure of balance control primarily for anterior and posterior added load conditions. Normalized by body mass (kg) including the mass of the load when applicable, body height (m), and [gravity*body height]^0.5 (m/s) resulting in a unitless number. | Posted | Mean | Standard Error | unitless | During study visit (approximately 3 hours) |
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Primary | Peak-to-peak Range of Coronal Plane Whole-body Angular Momentum (Normalized) | A measure of balance control primarily for intact-side added load conditions. Normalized by body mass (kg) including the mass of the load when applicable, body height (m), and [gravity*body height]^0.5 (m/s) resulting in a unitless number. | Posted | Mean | Standard Error | unitless | During study visit (approximately 3 hours) |
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Primary | Net Positive Ankle Joint Mechanical Work Over the Prosthetic Limb Gait Cycle (Normalized) | Positive ankle joint mechanical work over the prosthetic limb gait cycle is a measure of propulsion capability. A prosthetic foot with greater propulsion capability may enhance gait efficiency during everyday ambulation. Normalized to body mass and the added load mass when applicable. | Posted | Mean | Standard Error | J/kg | During study visit (approximately 3 hours) |
|
1 week
In this study, subjects only wore the study prosthetic feet while in the laboratory under supervision of laboratory staff. Because the study prosthetic feet could be quickly changed in between walking conditions (no added load, load added to the anterior side, load added to the posterior side, load added to the prosthetic side, and load added to the intact side), adverse events for all arms/groups and interventions were combined.
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| ID | Title | Description | Deaths (Affected) | Deaths (At Risk) | Serious Events (Affected) | Serious Events (At Risk) | Other Events (Affected) | Other Events (At Risk) |
|---|---|---|---|---|---|---|---|---|
| EG000 | Individuals With Lower Limb Amputation | In this cross-over study, all subjects were asked to with no added load and four added load conditions using a weighted pack (13.6 kg or ~30 lbs) to simulate an infant, toddler, or other load. The four conditions include the pack strapped to their front (anterior), their back (posterior), and carried with their arms on the intact limb side and the prosthetic limb side. The load conditions were presented in block randomized order. While performing each of these activities, the participant wore five different prosthetic feet. These prosthetic feet included a standard-of-care prosthetic foot, this same prosthetic foot with a heel-stiffening wedge, this same prosthetic foot but one category stiffer, a dual keel prosthetic foot intended for load carriage applications, and a powered ankle-foot purported to adapt to changing loads. The prosthetic feet were worn in randomized order and the subject was blinded to the study foot using a sock and foot cover when possible (wearing a powered ankle-foot is obvious to the participant). The study was conducted over two visits with overnight rest in between each visit. During the first study visit, each study foot was aligned to the participant's prosthesis and wore each for at least 15 minutes. During the second study visit, the participant walked wearing each of the five different study feet while performing each of the five different load conditions. | 0 | 12 | 0 | 12 | 0 | 12 |
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| Title | Organization | Phone | Extension | |
|---|---|---|---|---|
| Glenn Klute, PhD | VA Center for Limb Loss and MoBility | 206-277-2962 | Glenn.Klute@va.gov |
| Prot_000.pdf |
| SAP | No | Yes | No | Statistical Analysis Plan | Sep 20, 2024 | Dec 19, 2025 | SAP_001.pdf |
| ICF | No | No | Yes | Informed Consent Form | Aug 4, 2022 | Jan 26, 2026 | ICF_003.pdf |
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| ID | Term |
|---|---|
| D061485 | Tobacco Use Cessation Devices |
| ID | Term |
|---|---|
| D013812 | Therapeutics |
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| Native Hawaiian or Other Pacific Islander |
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| Black or African American |
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| White |
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| More than one race |
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| Unknown or Not Reported |
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| Unknown or Not Reported |
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| Walking with posterior load |
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| Walking with anterior load |
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| Walking with load on prosthetic side |
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| Walking with load on intact side |
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Walking with posterior load: Hypothesis testing for the overall association between outcome and foot type was carried out using conditional F-tests for each load type. |
| Regression, Linear |
| 0.032 |
| Superiority |
| Walking with posterior load: Hypothesis testing for pairwise differences across feet was carried out using Tukey's method to account for the inflation of the Type 1 error due to assessment of 10 pairwise differences for each load. | Regression, Linear | 0.024 | Superiority |
| Walking with posterior load: Hypothesis testing for pairwise differences across feet was carried out using Tukey's method to account for the inflation of the Type 1 error due to assessment of 10 pairwise differences for each load. | Regression, Linear | .046 | Superiority |
| Walking with anterior load: Hypothesis testing for the overall association between outcome and foot type was carried out using conditional F-tests for each load type. | Regression, Linear | .180 | Superiority |
| Walking with prosthetic side load: Hypothesis testing for the overall association between outcome and foot type was carried out using conditional F-tests for each load type. | Regression, Linear | .076 | Superiority |
| Walking with intact side load: Hypothesis testing for the overall association between outcome and foot type was carried out using conditional F-tests for each load type. | Regression, Linear | 0.210 | Superiority |
| OG004 | Powered Ankle-foot | A powered prosthetic ankle-foot. |
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A prosthetic foot with two forefoot keels intended for load carriage applications. |
| OG004 | Powered Ankle-foot | A powered prosthetic ankle-foot. |
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A prosthetic foot with two forefoot keels intended for load carriage applications.
| OG004 | Powered Ankle-foot | A powered prosthetic ankle-foot. |
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A prosthetic foot with two forefoot keels intended for load carriage applications. |
| OG004 | Powered Ankle-foot | A powered prosthetic ankle-foot. |
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