547 matching studies

Sponsor Condition of Interest
Decision Support Training for Advanced Cancer Family Caregivers: The CASCADE Factorial Trial
University of Alabama at Birmingham Family Members Cancer
Using a highly innovative methodology, the Multiphase Optimization Strategy (MOST), the purpose of this randomized factorial trial is to identify components of a intervention (CASCADE) to enhance the decision support skills of family caregivers of persons with newly-diagnosed advanced cancer. Using1 expand

Using a highly innovative methodology, the Multiphase Optimization Strategy (MOST), the purpose of this randomized factorial trial is to identify components of a intervention (CASCADE) to enhance the decision support skills of family caregivers of persons with newly-diagnosed advanced cancer. Using a 2x2x2x2 full factorial design, 256 family caregivers of persons with newly-diagnosed advanced cancer will be randomized to receive one or more nurse coach-delivered decision partnering training components, based on the Ottawa Decision Support Framework and Social Support Effectiveness Theory: 1) psychoeducation on effective decision partnering principles (1 vs. 3 sessions); 2) decision partnering communication training (yes vs. no); 3) Ottawa Decision Guide training (yes vs. no); and monthly follow (1 monthly follow-up call vs. monthly follow-up calls for 24 weeks).

Type: Interventional

Start Date: Jan 2022

open study

Video Telehealth Exercise Training in Cystic Fibrosis
University of Alabama at Birmingham Cystic Fibrosis
The purpose of this research study is to begin an exercise program for patients with a cystic fibrosis (CF) exacerbation. expand

The purpose of this research study is to begin an exercise program for patients with a cystic fibrosis (CF) exacerbation.

Type: Interventional

Start Date: Jul 2022

open study

T-DM1 and Tucatinib Compared with T-DM1 Alone in Preventing Relapses in People with High Risk HER2-1
Alliance for Clinical Trials in Oncology Anatomic Stage IA Breast Cancer AJCC V8 Anatomic Stage II Breast Cancer AJCC V8 Anatomic Stage IIA Breast Cancer AJCC V8 Anatomic Stage IIB Breast Cancer AJCC V8 Anatomic Stage III Breast Cancer AJCC V8
This phase III trial studies how well trastuzumab emtansine (T-DM1) and tucatinib work in preventing breast cancer from coming back (relapsing) in patients with high risk, HER2 positive breast cancer. T-DM1 is a monoclonal antibody, called trastuzumab, linked to a chemotherapy drug, called DM1. Tra1 expand

This phase III trial studies how well trastuzumab emtansine (T-DM1) and tucatinib work in preventing breast cancer from coming back (relapsing) in patients with high risk, HER2 positive breast cancer. T-DM1 is a monoclonal antibody, called trastuzumab, linked to a chemotherapy drug, called DM1. Trastuzumab is a form of targeted therapy because it attaches to specific molecules (receptors) on the surface of cancer cells, known as HER2 receptors, and delivers DM1 to kill them. Tucatinib may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth. Giving T-DM1 and tucatinib may work better in preventing breast cancer from relapsing in patients with HER2 positive breast cancer compared to T-DM1 alone.

Type: Interventional

Start Date: Mar 2021

open study

Using Early Time Restricted Feeding and Timed Light Therapy to Improve Glycemic Control in Adults W1
University of Alabama at Birmingham Diabetes Mellitus, Type 2 Time Restricted Feeding Light; Therapy, Complications
The purpose of this study is to test whether eating earlier in the day and/or timed light therapy can improve blood sugar in people with type 2 diabetes. This study will also test whether these treatments improve other aspects of health, including the circadian (biological) clock, sleep, weight, bo1 expand

The purpose of this study is to test whether eating earlier in the day and/or timed light therapy can improve blood sugar in people with type 2 diabetes. This study will also test whether these treatments improve other aspects of health, including the circadian (biological) clock, sleep, weight, body composition, cardiovascular health, quality of life, and mood.

Type: Interventional

Start Date: Apr 2021

open study

Influence of Metabolic Syndrome on Endogenous Oxalate Synthesis
University of Alabama at Birmingham MASLD Metabolic Dysfunction-Associated Steatotic Liver Disease
This study aims to determine the daily rate of endogenous synthesis of oxalate using fasted urine collection and a low-oxalate controlled diet in patients with Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD). expand

This study aims to determine the daily rate of endogenous synthesis of oxalate using fasted urine collection and a low-oxalate controlled diet in patients with Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD).

Type: Interventional

Start Date: Apr 2023

open study

PREVENT ALL ALS Study
St. Joseph's Hospital and Medical Center, Phoenix Amyotrophic Lateral Sclerosis
The ALL ALS Clinical Research Consortium is establishing research to collect a wide range of samples, clinical information and measurements from Amyotrophic Lateral Sclerosis (ALS) symptomatic, ALS gene carriers and control cohorts. This consortium is begin funded by the National Institutes of Heal1 expand

The ALL ALS Clinical Research Consortium is establishing research to collect a wide range of samples, clinical information and measurements from Amyotrophic Lateral Sclerosis (ALS) symptomatic, ALS gene carriers and control cohorts. This consortium is begin funded by the National Institutes of Health/National Institute of Neurological Disorders and Stroke (NIH/NINDS) and managed by two clinical coordinating centers (CCC) at Barrow Neurological Institute and Massachusetts General Hospital. The clinical sites are distributed across the country, and led by a group of collaborative principal investigators. Once data and samples are collected and harmonized, it will be made available to research community for future research into ALS and related neurological diseases. PREVENT protocol is specific for asymptomatic participants who are genetically at risk for ALS. The participants will be followed for up to 36 months (3 years), and will include 4 in-person on-site visits once a year and 6 off-site(remote) visits once in 4 months. The study includes collection of medical history, clinical outcomes, and blood samples once in 4 months. Additionally, the participants will complete patient reported outcomes and speech recordings once in 4 months. Participants may also provide optional Cerebrospinal Fluid (CSF) samples.The participants may also opt into a sub-study if they are interested in genetic testing for ALS causative genes. The sub-study will involve a minimum of 3 visits over a course of 2-3 months. This will include a screening/pre-test genetic counseling visit, a return of genetic results and a post-test counseling visit.

Type: Observational

Start Date: Jul 2024

open study

Testimonials and Navigation in Rheumatology
University of Alabama at Birmingham Rheumatologic Disease Autoimmune Diseases
The overall goal of this study is to determine whether a novel, multi-modal, patient-directed behavioral intervention initiated in rheumatology clinics is an effective approach to improve uptake of updated COVID-19 vaccine. expand

The overall goal of this study is to determine whether a novel, multi-modal, patient-directed behavioral intervention initiated in rheumatology clinics is an effective approach to improve uptake of updated COVID-19 vaccine.

Type: Interventional

Start Date: Dec 2024

open study

RESTORE: An RCT to Evaluate the Efficacy of the Revi System
BlueWind Medical Urinary Urge Incontinence
The Revi System is indicated for the treatment of patients with symptoms of urgency incontinence alone or in combination with urinary urgency. expand

The Revi System is indicated for the treatment of patients with symptoms of urgency incontinence alone or in combination with urinary urgency.

Type: Interventional

Start Date: Feb 2024

open study

Positron Emission Tomography (PET) Imaging of Neuroinflammation in Patients with Neurological Dysfu1
University of Alabama at Birmingham SARS CoV-2 Post-Acute Sequelae
This clinical imaging study will use the small molecule translocator protein (TSPO) ligand, Fluorodeoxyglucose(18F)-labeled DPA-714, to visualize and quantify neuroinflammation in individuals with post-acute sequelae of SARS-CoV-2 (PASC) . The brain uptake of DPA-714 will be contrasted with healthy1 expand

This clinical imaging study will use the small molecule translocator protein (TSPO) ligand, Fluorodeoxyglucose(18F)-labeled DPA-714, to visualize and quantify neuroinflammation in individuals with post-acute sequelae of SARS-CoV-2 (PASC) . The brain uptake of DPA-714 will be contrasted with healthy subjects.

Type: Interventional

Start Date: Nov 2023

open study

Multiparametic Metabolic and Hypoxic PET/MRI for Disease Assessment in High Grade Glioma
University of Alabama at Birmingham High Grade Glioma
This feasibility study will assess the clinical potential of a new imaging approach to detect viable high grade glioma (HGG) in pediatric and adult patients after standard of care radiation therapy (RT) with or without concurrent temozolomide (TMZ). Study participants will undergo simultaneous posi1 expand

This feasibility study will assess the clinical potential of a new imaging approach to detect viable high grade glioma (HGG) in pediatric and adult patients after standard of care radiation therapy (RT) with or without concurrent temozolomide (TMZ). Study participants will undergo simultaneous positron emission tomography/magnetic resonance imaging (PET/MRI) with O-([2-[F-18]fluoroethyl)-L-tyrosine (FET, amino acid transport) and 1H-1-(3-[F-18]fluoro-2-hydroxypropyl)-2-nitroimidazole (FMISO, hypoxia) at the time of standard of care imaging after completion of RT. The presence of viable tumor at this time point will be assessed on a per patient basis. Study participants will be followed clinically and with standard of care (SOC) imaging for up to 2 years after completion of PET/MRI to determine the nature of lesions seen on investigational imaging and to obtain patient outcome data. The imaging data will also be used to develop a semi-automated workflow suitable for implementation in clinical trials and standard of care PET/MRI studies.

Type: Interventional

Start Date: Mar 2024

open study

Neuroinflammation in Asymptomatic Carotid Artery Disease - Imaging Substudy
University of Alabama at Birmingham Critical Asymptomatic Carotid Artery Disease Non-Critical Asymptomatic Carotid Artery Disease
This clinical imaging substudy will use the small molecule translocator protein (TSPO) ligand, Fludeoxyglucose(18F)-labeled DPA-714, to compare neuroinflammation in individuals with high or low grade asymptomatic carotid artery stenosis (aCAD) who are participating in the separate Neuroinflammation1 expand

This clinical imaging substudy will use the small molecule translocator protein (TSPO) ligand, Fludeoxyglucose(18F)-labeled DPA-714, to compare neuroinflammation in individuals with high or low grade asymptomatic carotid artery stenosis (aCAD) who are participating in the separate Neuroinflammation in Asymptomatic Carotid Artery Disease study lead by Dr. Ron Lazar (IRB-300007806). The positron emission tomography (PET) tracer [18F]DPA-714 binds to the 18 kDa translocator protein (TSPO, also known as the peripheral benzodiazepine receptor) in the mitochondria of activated microglia/macrophages and provides a non-invasive measure of neuroinflammation.

Type: Interventional

Start Date: Apr 2026

open study

Hyperhydration in Children With Shiga Toxin-Producing E. Coli Infection
University of Calgary Shiga Toxin-Producing Escherichia Coli (E. Coli) Infection Hemolytic-Uremic Syndrome
The objective of this study is to determine if early high volume intravenous fluid administration (hyperhydration) may be effective in mitigating or preventing complications of shiga toxin-producing E. coli (STEC) infection in children and adolescents when compared with traditional approaches (cons1 expand

The objective of this study is to determine if early high volume intravenous fluid administration (hyperhydration) may be effective in mitigating or preventing complications of shiga toxin-producing E. coli (STEC) infection in children and adolescents when compared with traditional approaches (conservative fluid management).

Type: Interventional

Start Date: Sep 2022

open study

Biomarker and Edema Attenuation in IntraCerebral Hemorrhage (BEACH)
Johns Hopkins University Intracerebral Hemorrhage
This first-in-patient phase 2a pilot study will assess the safety and tolerability of MW01-6-189WH (hereafter called MW189) in patients with Intracerebral Hemorrhage (ICH). expand

This first-in-patient phase 2a pilot study will assess the safety and tolerability of MW01-6-189WH (hereafter called MW189) in patients with Intracerebral Hemorrhage (ICH).

Type: Interventional

Start Date: Oct 2022

open study

Feasibility of a New Model for Exercise Prescription in Cystic Fibrosis
University of Alabama at Birmingham Cystic Fibrosis
The purpose of this protocol is to begin an exercise program combined with behavioral counseling for patients who are hospitalized with a cystic fibrosis exacerbation. The exercise program will begin during the hospital stay. Beginning an exercise program during this period of reduced mobility and1 expand

The purpose of this protocol is to begin an exercise program combined with behavioral counseling for patients who are hospitalized with a cystic fibrosis exacerbation. The exercise program will begin during the hospital stay. Beginning an exercise program during this period of reduced mobility and isolation may be an ideal time to deliver a structured exercise prescription along with a behavioral program to promote long-term adherence to exercise (structured physical activity) . Hospitalized patients have an acute awareness that their lung function is declining and may be more motivated and open to changing their behavior and adding exercise to their treatment regimen.

Type: Interventional

Start Date: Dec 2020

open study

HCRN Core Data Project: Characterizing Patient Populations in the Hydrocephalus Clinical Research N1
University of Utah Pediatric Hydrocephalus
The Hydrocephalus Clinical Research Network (HCRN) has been established by philanthropic funding to conduct multi-institutional research (clinical trials and observational studies) on pediatric hydrocephalus. In addition to philanthropic funding, the HCRN has also received an NIH NINDS Challenge Gr1 expand

The Hydrocephalus Clinical Research Network (HCRN) has been established by philanthropic funding to conduct multi-institutional research (clinical trials and observational studies) on pediatric hydrocephalus. In addition to philanthropic funding, the HCRN has also received an NIH NINDS Challenge Grant to support the network infrastructure which allows for the conduct of this and other network studies. The HCRN consists of multiple Clinical Centers and the Data Coordinating Center (DCC). The HCRN Core Data Project will obtain data about all neurosurgical hydrocephalus events from the network Clinical Centers, and create a database to be used by HCRN investigators. The ongoing maintenance of the Core Data Project serves two main purposes: 1) it will help investigators understand the variability, progression, and current treatment practices for hydrocephalus in children, with an ultimate goal of better guiding and assessing therapeutic intervention and providing recommendations on patient care and, 2) it will provide pilot and descriptive data necessary for hypothesis generation and study design (i.e. preliminary power analyses, recruitment projections) for studies under development by the HCRN. This multi-institutional database will be maintained throughout the lifetime of the HCRN, and may be useful for tracking trends in pediatric hydrocephalus over time. The Core Data Project will be an invaluable resource to the HCRN and will help stimulate new research protocols, identify potential need for future expansion of the network to incorporate additional patient populations, and provide a descriptive understanding of children with hydrocephalus cared for within the network.

Type: Observational

Start Date: Apr 2008

open study

Stimulus-Evoked Directional Field Potentials to Guide Subthalamic and Pallidal DBS for PD
University of Alabama at Birmingham Parkinson Disease
Our goal is to better understand how DBS modifies local neuronal activity and to pioneer device technologies that can record local DBS-evoked potentials (DLEPs) to guide therapy. Our vision is for a patient's unique electrophysiology to guide both electrode targeting during surgery and programming1 expand

Our goal is to better understand how DBS modifies local neuronal activity and to pioneer device technologies that can record local DBS-evoked potentials (DLEPs) to guide therapy. Our vision is for a patient's unique electrophysiology to guide both electrode targeting during surgery and programming in clinic, eventually as an integrated component of the implanted pulse generator. Our results will inform directional DBS for PD and serve as a model for translation to other diseases where knowledge on DBS circuit interactions is at an even earlier stage.

Type: Interventional

Start Date: Jan 2024

open study

Tracking Peripheral Immune Cell Infiltration of the Brain in Central Inflammatory Disorders Using [1
University of Alabama at Birmingham Fibromyalgia Chronic Fatigue Syndrome Multiple Sclerosis Healthy
This study will use brain Positron Emission Tomography/ Magnetic Resonance Imaging (PET/MRI) and an investigational radioactive drug called [Zr-89]oxine to track the location of white blood cells (also called leukocytes) in the body. PET/MRI will be used to visualize labeled white blood cells and d1 expand

This study will use brain Positron Emission Tomography/ Magnetic Resonance Imaging (PET/MRI) and an investigational radioactive drug called [Zr-89]oxine to track the location of white blood cells (also called leukocytes) in the body. PET/MRI will be used to visualize labeled white blood cells and determine if they enter the central nervous system in conditions associated with brain inflammation (also called neuroinflammation). By better understanding the role of neuroinflammation in fibromyalgia, chronic fatigue syndrome, and multiple sclerosis, the investigator hopes to be able to better diagnose and treat patients in the future.

Type: Interventional

Start Date: Oct 2021

open study

The EndRAD Trial: Eliminating Total Body Irradiation (TBI) for NGS-MRD Negative Children, Adolescen1
Pediatric Transplantation & Cellular Therapy Consortium B-cell Acute Lymphoblastic Leukemia
This study will evaluate the use of non- TBI (total body irradiation) conditioning for B-ALL patients with low risk of relapse as defined by absence of NGS-MRD (next generation sequencing minimal residual disease) before receiving a hematopoietic cell transplant (HCT). Patients diagnosed with B-ALL1 expand

This study will evaluate the use of non- TBI (total body irradiation) conditioning for B-ALL patients with low risk of relapse as defined by absence of NGS-MRD (next generation sequencing minimal residual disease) before receiving a hematopoietic cell transplant (HCT). Patients diagnosed with B-ALL who are candidates for HCT will be screened by NGS-MRD on a test of bone marrow done before the HCT. Subjects who are pre-HCT NGS-MRD negative will be eligible to receive a non-TBI conditioning regimen as part of the treatment cohort of the study. Subjects who are pre-HCT NGS-MRD positive will be treated as per treating center standard and will be followed in an observational cohort (HCT center standard of care).

Type: Interventional

Start Date: Aug 2018

open study

Reducing Vertical Transmission of Hepatitis B in Africa
University of Alabama at Birmingham Hepatitis B Infection
Hepatitis B virus is an infection that can be easily transmitted from women to newborns at the time of delivery. Our objective is to identify novel options that are effective and safe in preventing perinatal transmission of hepatitis B in Africa. The REVERT-B study (Reducing Vertical Transmission o1 expand

Hepatitis B virus is an infection that can be easily transmitted from women to newborns at the time of delivery. Our objective is to identify novel options that are effective and safe in preventing perinatal transmission of hepatitis B in Africa. The REVERT-B study (Reducing Vertical Transmission of Hepatitis B in Africa) is a clinical trial designed to test a new strategy of using antiviral medication in high-risk pregnant women and newborns to reduce the risk of hepatitis B transmission. The study will measure efficacy, safety, tolerability and adherence to medication.

Type: Interventional

Start Date: Sep 2021

open study

Glycemic Control After Antenatal Corticosteroids in Women with Pregestational and Gestational Diabe1
University of Alabama at Birmingham Diabetes Mellitus, Type 2 Preterm Birth Pregnancy, High Risk Diabetes, Gestational
There is a fundamental gap in understanding the maternal and neonatal effects of antenatal corticosteroid (ACS) administration in women with threatened preterm birth (PTB) who have diabetes. Since the initial discovery of ACS for neonatal benefit in 1972, more than 40 randomized controlled trials h1 expand

There is a fundamental gap in understanding the maternal and neonatal effects of antenatal corticosteroid (ACS) administration in women with threatened preterm birth (PTB) who have diabetes. Since the initial discovery of ACS for neonatal benefit in 1972, more than 40 randomized controlled trials have been performed evaluating its efficacy. However, none of these trials have included women with T2DM, and there is limited data among women with gestational diabetes. While ACS have been shown to reduce neonatal morbidity associated with PTB in non-diabetic women, the side effects of ACS (maternal hyperglycemia and fetal hyperinsulinemia) may mitigate the neonatal benefit of ACS in women with diabetes. Before neonatal benefit of ACS can be evaluated in this population, the first step is to optimize maternal glycemic control after ACS. Previous studies evaluating maternal hyperglycemia after ACS have been limited by small sample size, retrospective study design, or insufficient glucose data. Use of continuous glucose monitoring (CGM) in a randomized clinical trial provides a unique opportunity to overcome these challenges. Our long-term goal is to improve maternal and child health among women with diabetes as an independently funded clinical researcher. The research objectives of this proposal are to test the efficacy of three treatment strategies at achieving maternal glycemic control after ACS and evaluate the association between maternal glycemic control and neonatal outcomes. Our central hypothesis is that treatment with a continuous insulin infusion will improve maternal glycemic control, which is key to improving neonatal outcomes, but at the cost of less patient satisfaction and more health resource utilization. This hypothesis will be tested by pursuing the following specific aims: 1) Test the efficacy of three treatment strategies (addition of sliding scale insulin, up-titration of home insulin, and continuous insulin infusion) at achieving maternal glycemic control after ACS and 2) Quantify the association between maternal glycemic control after ACS and neonatal morbidity. Completion of these aims will determine the optimal strategy to achieve maternal glycemic control after ACS and inform a larger, multicenter trial to improve neonatal outcomes among women with diabetes and threatened PTB.

Type: Interventional

Start Date: Feb 2022

open study

KT Tape for Pediatric Clavicle Fractures
University of Alabama at Birmingham Clavicle Fracture
Clavicle fractures in children are mostly managed non-operatively since they have an overall high union rate (95%) and a "good" functional outcome following nonoperative treatment. However, the downside of such a conservative approach is that patients have to live with pain and disability until the1 expand

Clavicle fractures in children are mostly managed non-operatively since they have an overall high union rate (95%) and a "good" functional outcome following nonoperative treatment. However, the downside of such a conservative approach is that patients have to live with pain and disability until the fracture heals. To minimize this, fractures are usually immobilized with a sling. There have been no studies looking at clavicle fractures treated with kinesiology (elastic) tape. No adverse effects (skin irritation, redness, etc.) are observed with the application of this tape. Elastic tape has previously been examined regarding muscular advantages rather than for healing fractures. Since this tape should immobilize fractures better than a sling, patients should experience less pain and disability associated with their fracture.

Type: Interventional

Start Date: Oct 2020

open study

International Weight Control Registry
Tufts University Weight Loss Overweight Obesity
The IWCR is a global scientific study aimed at better understanding the opportunities and barriers for reducing the prevalence of obesity by collecting information from people who have experience with weight management in their everyday lives. The investigators seek to gather information on a wide1 expand

The IWCR is a global scientific study aimed at better understanding the opportunities and barriers for reducing the prevalence of obesity by collecting information from people who have experience with weight management in their everyday lives. The investigators seek to gather information on a wide range of weight management experiences, ranging from weight loss and weight loss maintenance to weight gain and inability to lose weight.

Type: Observational [Patient Registry]

Start Date: Dec 2020

open study

I-SPY COVID-19 TRIAL: An Adaptive Platform Trial for Critically Ill Patients
QuantumLeap Healthcare Collaborative COVID-19
The goal of this project is to rapidly screen promising agents, in the setting of an adaptive platform trial, for treatment of critically ill COVID-19 patients. In this phase 2 platform design, agents will be identified with a signal suggesting a big impact on reducing mortality and the need for, a1 expand

The goal of this project is to rapidly screen promising agents, in the setting of an adaptive platform trial, for treatment of critically ill COVID-19 patients. In this phase 2 platform design, agents will be identified with a signal suggesting a big impact on reducing mortality and the need for, as well as duration, of mechanical ventilation.

Type: Interventional

Start Date: Jul 2020

open study

Regulation of Inflammatory Genes in Psoriasis
University of Alabama at Birmingham Psoriasis Inflammation
Psoriasis is a chronic and recurrent skin disorder characterized by marked inflammatory changes in the skin. An extensive cytokine network including generated by activated dendritic cells and T cells mediates the formation of psoriatic lesions. These immune-response parameters can be used as marker1 expand

Psoriasis is a chronic and recurrent skin disorder characterized by marked inflammatory changes in the skin. An extensive cytokine network including generated by activated dendritic cells and T cells mediates the formation of psoriatic lesions. These immune-response parameters can be used as markers in the severity and management of the disease after further in-depth studies.

Type: Observational

Start Date: Apr 2014

open study

Validation of Early Prognostic Data for Recovery Outcome After Stroke for Future, Higher Yield Tria1
University of Cincinnati Stroke Stroke, Acute Stroke, Ischemic Stroke Hemorrhagic
VERIFY will validate biomarkers of upper extremity (UE) motor outcome in the acute ischemic stroke window for immediate use in clinical trials, and explore these biomarkers in acute intracerebral hemorrhage. VERIFY will create the first multicenter, large-scale, prospective dataset of clinical, tra1 expand

VERIFY will validate biomarkers of upper extremity (UE) motor outcome in the acute ischemic stroke window for immediate use in clinical trials, and explore these biomarkers in acute intracerebral hemorrhage. VERIFY will create the first multicenter, large-scale, prospective dataset of clinical, transmagnetic stimulation (TMS), and MRI measures in the acute stroke time window.

Type: Observational

Start Date: Jun 2022

open study