Research Faculty and Staff

Navkiran Shokar is a clinician scientist, and her background and training in family medicine, public health, and clinical research has led her to pursue research in cancer prevention, early detection, and health disparities. Dr. Shokar’s research has focused largely on disparities in cancer screening, particularly as applied to colorectal, but also cervical, breast, and prostate cancer. Much of her research is guided by a socioecological framework and requires multilevel approaches to the problem. She incorporates a multidisciplinary, team-based approach and has many interinstitutional, collaborative projects. Her current research foci are: targeted and culturally tailored community-based cancer screening interventions (colorectal, breast, and cervical) for Hispanic populations; clinic-based, shared decision-making and informed decision-making interventions for colorectal cancer screening; interventions to improve the uptake of diagnostic tests after an abnormal screen; quantifying risks in Hispanic communities for cervical cancer, breast cancer, and colorectal cancer; translational research focusing on dissemination and testing of interventions in new populations; and understanding the lifestyle, biological, environmental, and genetic determinants of cancer risk, cancer screening behavior, and cancer outcomes in Hispanic populations.

Education

• Cambridge University England, B.A. / M.A. Cantab, anatomy (1989)
• Oxford University Medical School, England, B.M. / B.Ch. (M.D.) (1992)
• University of Texas School of Public Health, Houston, Texas, M.P.H. (2003)

Honors

• 2016 Top Doctor in El Paso, International Association of Health Care Professionals: Leading Physicians of the World
• 2016 TTUHSC El Paso Chancellor’s Award for Excellence in Research
• 2014 Dean’s Excellence in Research Award, TTUHSC El Paso
• 2011-2016 Best Doctors in America
• 2011 Dean’s Award for Excellence in Research TTUHSC El Paso
• 2011- 2015 Best Doctors in America
• 2006 Interdisciplinary Research in Women’s Health Scholar, NIH/NICHD and Office of Research in Women’s Health (ORWH), K12, PI: Abbey Berenson, M.D.
• 1999 Senior Resident of the Year at St. Joseph Family Practice Residency Program
• 1998 Resident of the Year at St. Joseph Family Practice Residency Program
• 1998-1999 Chief Resident, St. Joseph Family Practice Residency Program
• Cancer Prevention and Research Institute of Texas, ACCION: Against Colorectal Cancer in Our Neighborhoods: El Paso and Hudspeth County, PP140164 (2015-2018)
• Cancer Prevention and Research Institute of Texas, De Casa 2: Cervical Cancer Prevention in El Paso and West Texas, PP170004 (2017-2020)
• Cancer Prevention and Research Institute of Texas; Southwest Coalition for Colorectal Cancer Screening, PP170068 (2017-2020)
• Cancer Prevention and Research Institute of Texas, Tiempo de Vacunarte! Time to Get Vaccinated!, PP140211 (2014-2018)
• Cancer Prevention and Research Institute of Texas, BEST 2: Breast Cancer Education Screening and Navigation Program for El Paso and West Texas, PP180003 (2018-2021)
• National Cancer Institute, Comparative Effectiveness of Fecal Immunochemical Testing with Optical Colonoscopy, R01CA215034 (2017-2022)

Jennifer Molokwu received her M.D. from College of Medicine, University of Benin in Edo State, Nigeria. She obtained an M.P.H. in maternal and child health with an emphasis in epidemiology at the School of Public Health University of Minnesota, Minneapolis, Minnesota. She is board certified in family medicine after completing residency training at Hennepin County Medical Center, Minneapolis, Minnesota in 2010. Her areas of interest include women’s health, cancer prevention, and primary care research. She was a co-investigator on an AAFP grant investigating U.S./Mexico border women attitudes toward using self-sampling methods to detect cervix/vagina infections with the human papillomavirus and was the Project Director for the Cancer Prevention Research Institutive of Texas (CPRIT) grant Time To Get Vaccinated/Tiempo De Vacunarte.

Education

• MBBS University of Benin Medical School, Nigeria (2002)
• P.H., School of Public Health, University of Minnesota, Minneapolis, MN (2007)

Honors

• 2016-Present Fellow, American Academy of Family Physicians
• 2013-Date Best Doctors of America Recognition 2013, 2014, 2015, 2016
• 2013 Clerkship Teaching Award. Department of Family and Community Medicine, TTUHSC/ PLFSOM
• 2010 Department of Family Medicine Award for Outstanding Research and Scholarly Activity. Hennepin County Medical Center, Minneapolis Minnesota
• 2010 Eldon Berglund Award for academic excellence, clinical competence, educational commitment and professional demeanor, Department of family medicine, Hennepin County Medical Center, Minneapolis Minnesota
• 2004 Health Equity Award, School of Public Health, University of Minnesota, Minneapolis Minnesota
• 2004 James L. Craig Fellowship in Public Health, School of Public Health, University of Minnesota, Minneapolis Minnesota

Jennifer Salinas is a health disparities researcher with a focus on the influence of social context on the etiology of chronic disease in the Mexican-origin population living in the United States and Mexico. She conducts research in both countries on social risk factors for diabetes, cardiovascular disease, and obesity. Over the past eight years her work has focused on the U.S.-Mexico border region by comparing border-residing Mexican Americans to those living in other parts of the United States, and in the Mexican interior. Currently, she is involved in three main projects: a promotora-led physical activity clinical trial, an El Paso-based obesity prevention program, and a breast cancer prevention and epidemiological study. Early findings from these efforts suggest that the unique social and economic environment of the Paso del Norte region serves as a barrier, as well as a facilitating factor, in the proliferation of specific diseases in the Mexican-origin population living in the region. Cultural issues may be beneficial, influencing behaviors that promote good health and prevent the onset of certain diseases. However, economic inequities, coupled with limited access to health-promoting resources, are risk factors that are not easily offset by the salubrious effects of traditional Mexican culture.

Education

• The University of Texas at Austin, Ph.D., Sociology-Demography (2006)
• University of Pennsylvania, M.S.W., Social Work (1995)
• University of Massachusetts at Amherst, B.A., Psychology (1993)

Honors

• DHHS – National Heart, Lung, and Blood Institute, R01HL111718 (2016-2018)

Over the past 13 years, Jessica Calderon-Mora has been involved in formative work, development of interventions, and implementation of cluster randomized trials related to prostate, breast, cervical, and colorectal cancer prevention. Ongoing projects in which she is currently involved address cancer disparities among Hispanics in our region, a large percentage of whom are living below poverty and are uninsured.  She has developed training manuals and conducted trainings for community health workers to implement screening programs and interventions among our Hispanic community. She has been intimately involved in the planning and implementation of community-based participatory research.

Through her role as a research instructor, she has taken the lead in implementing, dissemination and implementation strategies into several of our programs, namely the colorectal cancer screening program, which she has been involved with since its inception. She is interested in determining how to increase the completion rate of mailed out screening tests to Hispanic patients from a federally qualified health center.

In the future as an independent researcher, she plans to conduct dissemination and implementation research along with independent community-based participatory research. She will also use her experience with community health workers to address health disparities within our community and region. Her career goal is to become an accomplished researcher who contributes greatly to health disparities research related to cancer among a growing Hispanic population in the Paso del Norte region. 

Education

• Stanford University, B.A., Human Biology and Psychology (2001)
• The University of Texas Health Science Center, School of Public Health, M.P.H. (2004)
• The University of Texas Health Science Center, School of Public Health, Dr.P.H. (2016)

Honors

• Master Certified Health Education Specialist (2005 - present)
• Delta Omega Honorary Society in Public Health, Alpha Iota Chapter (2005 - present)

I have the experience of working with children as a clinician for more than two decades. My research interests have been shaped by my active participation in several binational research projects on the U.S.-Mexico border examining the impact of diesel exposure and traffic-related air pollution on asthmatic children.

During the last five years I have gained valuable expertise in community-based cancer prevention particularly as it relates to colo-rectal, breast and cervical cancer screening, and cancer education for the Hispanic population.

One of my achievements has included developing and maintaining research databases for four ongoing cancer prevention projects. I have participated in analysis of data for scientific reports about children’s research and cancer prevention in the Border region.

Further areas of interest include applying and promoting cultural competence in research to address cancer prevention, and clinical and epidemiological research on obesity, metabolic syndrome and cardiovascular risk in children.

Education and academic positions

• Autonomous University of Nuevo Leon, Faculty of Medicine, Mexico (MD)(1984).
• Mexican Social Security Institute, Monterrey, Mexico Pediatric Residency (1986-1989).
• Pediatrician Mexican Social Security Institute, Hospital 6, Cd. Juarez, Chihuahua, Mexico (1990-2006).
• Institute National Public Health , M.Sc., Environmental Health (1999-2000).
• Environmental Health Advisor, Pan-American Health Organization El Paso, Texas (2003-2004).
• Chief of Pediatric Department, Mexican Social Security Institute, Regional Hospital 66, Ciudad Juarez, Chihuahua ( 2006-2013).
• Postdoctoral position, University of Texas at El Paso College of Health Science Department of Health Promotion (2007-2008).
• Graduate Research Associate, University of Texas at El Paso College of Health Science Department of Health Promotion (2009-2011).
• University of Texas at El Paso, Ph.D., Interdisciplinary Health Sciences (2008-2013).
• Senior Research Associate, Texas Tech University Health Sciences Center El Paso, Paul L. Foster School of Medicine, Department of Family and Community Medicine (2014-2016).
• Pediatric private practice; Monterrey Mexico (2017-2019).
• Research Assistant Professor, Texas Tech University Health Sciences Center El Paso, Center of Emphasis in Cancer, Department of Molecular and Translational Medicine, Paul L. Foster School of Medicine, El Paso, Texas (2019-present).

Honors (fellowships, career development awards, endowments, etc.)

• In 2007, I received a Janacek Postdoctoral Fellowship at UTEP to conduct of a clinical research in chronic disease in overweight Mexican and Mexican American adolescents.
• Other fellowships included a graduate research assistant position at the UTEP College of Health Science, which I received two years in a row (2010-2011) and several competitive travel grants to national meetings. 

Link to PubMed publications

View Dr. Silvia Flores-Luevano's publications.

Rebekah Salaiz, M.S., joined TTUHSC El Paso in 2011 as a health educator, where she became a trained diabetes educator with the Diabetes Empowerment Education Program (DEEP) from TMF Health Quality Institute to provide diabetes education classes to Family Medicine patients. In 2013, she became a research associate (program coordinator) for ACCION, a colorectal cancer program funded by the Cancer and Research Institute of Texas (CPRIT), where she was involved in the development, implementation, and coordination of the program. Soon after gaining experience with ACCION, in 2014 she became a senior research associate, working closely with the vice chair for research to ensure that all CPRIT programs were being implemented and that both institutional and funding agency policies and procedures were being followed. Previously, she worked with the University of Texas at El Paso (UTEP) College of Health Sciences for two grant-funded programs in substance abuse prevention as an intervention coordinator and program manager. She is now director of the research division of the Department of Family and Community Medicine. Rebekah obtained a B.S. in health sciences in 2004 and a M.S in health promotion from UTEP in 2007. Her hobbies include spending time with her family.

Adam Alomari, M.P.H., completed his undergraduate degree from the University of Texas at El Paso with a focus in sociology and health promotion in 2011. He earned an M.P.H. and a certificate in public health informatics in 2014 from the University of Texas Health Science Center (UTHSC) at Houston, where he is additionally concluding a second master’s in biomedical informatics. Throughout his academic career, he has held numerous research positions at UTHSC at Houston, TTUHSC El Paso, and the Paso Del Norte Institute for Healthy Living, all of which have been grant-funded projects focusing on health, prevention, and awareness. During his time in research at the Department of Family Medicine, he has managed the coordination of various cancer prevention programs, database design, data management, along with survey and manuscript development.

Pracheta Matharasi, M.P.H., obtained her M.P.H from the University of Texas at El Paso (UTEP) in 2017 with honors. During her master’s program, she gained work experience as a research assistant, with job responsibilities including literature review, data collection, and data analysis. The projects that she worked on are Healthy Eating and Active Living (HEAL) and the Environmental Lead study. She also worked as a teaching assistant for biology undergraduate students at UTEP. Pracheta joined the TTUHSC El Paso Department of Family and Community Medicine in January 2018 as a research associate for the SuCCCeS program.

Gaby Herrera, M.S., received her B.S. in Health Promotion with a minor in Community Health from the University of Texas at El Paso (UTEP) in 2005 and her M.S. in Mental Health and Wellness from Grand Canyon University in 2018. From 2005-2008, she worked at UTEP as a Facilitator for a substance abuse prevention program for children ages 5-12 and as an Intervention Coordinator for a program aimed at reducing the incidence of binge drinking among college students. After UTEP, she worked as a Health Educator for Southern New Mexico Human Development with a program geared at reducing drug use and truancy among at-risk high school students in the Gadsden Independent School District. She later went on to work at the City of El Paso Department of Public Health as a Health Education and Prevention Specialist. While at the Health Department, she worked on programs related to tobacco prevention, sexual health, and community and worksite wellness. She is also certified in Mental Health First Aid for Adults and Youth. Gaby joined the TTUHSC El Paso Department of Family and Community Medicine in January 2019 as a Research Associate for the BEST program.

Joe Padilla obtained a bachelor’s of Kinesiology from the University of Texas at El Paso and a Master’s in Public Health from New Mexico State University in 2018.  During his master’s program, he gained work experience as a Research Assistant for the NMSU Cancer Outreach Program, where he assisted in data collection and data analysis. The project he worked on was the program evaluation of the Culturally Adapted Colorectal Cancer Educational Program for Hispanics. His other efforts include developing educational materials that promote cancer screening among Hispanics. He completed a master’s thesis project examining "Factors Affecting CRC screening in Hispanics of Mexican Descent." Joe Joined the TTUHSC El Paso Department of Family and Community Medicine in February 2019 as a research associate for the SuCCCeS program. His current job responsibilities include working with the community, managing Community Health Workers and coordinating the program.

Jon Sheen, M.P.H., earned a bachelor’s degree in anthropology from Texas A&M University in 2015. He earned his M.P.H. in epidemiology in 2017 from the University of Texas Health Science Center at Houston. During his studies, Jon worked as a data collector for Brighter Bites, a non-profit health promotion program based out of Houston and interned at the University of Texas at Austin's Environmental Health and Safety department, revising components of the biological safety program. Jon joined the TTUHSC El Paso Department of Molecular and Translational Medicine Center of Emphasis in Cancer in May 2018.

Samantha Nicholson obtained a Bachelor of Business Administration with a concentration in finance from the University of Texas at El Paso. She has previously worked for the YMCA, which gave her the opportunity to expand her career and give back to the community. Samantha has been with the TTUHSC El Paso Department of Family and Community Medicine research division since December 2017.

Mateo Duran holds an associate’s degree in liberal arts from El Paso Community College (EPCC) and a Bachelor of Arts degree in multidisciplinary studies from the University of Texas at El Paso (UTEP). Prior to attending college, Mateo served in the military honorably for 11 years in both the Army and Navy. He is proud to say that he has served TTUHSC El Paso for about 10 years in the departments of Internal Medicine, Family Medicine, and Pediatrics in various capacities such as CNA, CMA, assistant clinic coordinator, and in his current role as coordinator. The majority of his responsibilities are data entry for grant-funded cancer research programs, including SuCCCeS (formerly ACCION 2) and De Casa en Casa. His goal is to make these programs as successful as possible to continue serving our community. While he enjoys a number of activities, such as gardening, cooking and bringing discarded lumber back to life as rustic furniture, his favorite time is spent as a volunteer coach for the city’s Parks and Recreation Department’s Youth Sports Programs. Says Mateo: “The evolution that is my life continues: never stop learning, never stop serving in all facets.”

Michael Joel Juarez joined TTUHSC El Paso in August 2018 as a Data Entry Specialist, working with various programs such as ACCION (Colorectal Cancer Program), De Casa En Casa (Cervical Cancer Prevention), as well as BEST (Breast Cancer Screening Program), all which are funded by the Cancer and Research Institute of Texas (CPRIT). He previously worked with civilian contractor’s processing through Fort Bliss’ CONUS Replacement Center for 4 years. His hobbies include music, watching sports, and spending time with family.

Marisela Cottrell, M.A., is a senior outreach worker with the research division of the Department of Family and Community Medicine at TTUHSC El Paso. She has a master’s degree in counseling, a bachelor’s degree in sociology, and an associate’s degree. She just completed a year-long community health worker certification program, she takes financial classes, and is presently taking some classes with the Dale Carnegie program. She studies other modalities such as Reiki, Prana, and Nuat Thai Massage. She is planning to start her doctorate degree soon, which has been her main life goal. She has worked in several agencies, which include Healthtrust in Houston for ten years with the Chronic Pain program, Lee & Beulah Moor Children’s Home, Family Service of El Paso, Head Start program, and other agencies within the El Paso region. She has been with TTUSHC El Paso for four years with the BEST program and De Casa en Casa Program. Her motto is to heal and become wiser to help others.

Sonia Escamilla holds an associate’s degree in social work. She has served as a senior outreach worker at TTUHSC El Paso for six months, providing navigation assistance to colorectal cancer screening participants. Some of her functions as a navigator include assisting participants in scheduling appointments, finding treatment assistance, providing test results, finding medical resources, making reminder calls for appointments, arranging transportation, and conducting intakes. Some of her previous job experiences include working as a navigator for the ACA program, providing education and assistance for enrolling in ACA insurance. Sonia also worked as a case worker with a case load of 40 participants. As a case worker, some of her duties were: to conduct home visits, assist participants in scheduling doctor appointments, and being a representative payee for Social Security benefits. Sonia enjoys serving in her church as a Sunday school teacher, spending time with her family, and baking. Says Sonia: “I believe in hard work, and I enjoy working hard.”

Bertha Macias joined TTUHSC El Paso in August 2018 as a Sr. Outreach Worker. Her past experience has been working with various nonprofit agencies in El Paso providing services to the community. She is very family oriented, and enjoys doing arts and crafts to share with family and friends.

Estrella D. Pena completed her Bachelor of Science in health promotion with a minor in community health in 2012. Estrella has previously worked at the University of Texas at El Paso (UTEP) as a reader scribe in the Center for Accommodations and Support Services (CASS). She has been with the TTUHSC El Paso Department of Family and Community Medicine research division for four years. She is currently working in the cervical cancer screening program, De Casa en Casa. Estrella spends her free time going to the Samalayuca Dunes, where she is part of the off-road and racing team Escuadron 4x4.

Brenda Quintanar holds a certificate as a community health worker. She is a senior outreach worker at the TTUHSC El Paso Department of Family and Community Medicine research division and has served as a navigator for five years. She helps with colorectal cancer screening tests for the community, providing results of the tests and helping those diagnosed with cancer find financial assistance for treatments and surgery, if needed. She also helps with follow-ups to specialists and primary care providers. She is experienced working in a busy office, including managing telephone calls and correspondence. She has excellent communication and interpersonal skills, as well as office management experience, including implementing and maintaining paper and electronic filing systems.

Hilda Flores completed a certificate program as a nursing assistant from Hospital Seguro Social in Mexico and an associate’s degree in humanities from Mexico. After moving to the United States, she obtained her certificate as a community health worker from El Paso Community College. She began her work as a community outreach worker as a volunteer with AmeriCorps through United Way, where she was involved in parent-relation classes. She then went on to work with the Texas A&M colonias program in El Paso, where she led other community outreach workers to organize food banks, toy drives, and nutritional classes. She has been with TTUHSC El Paso since 2012, first with the ACCION program and then the BEST program.

Rosa Maria Gonzalez was born and raised in Torreón, Coahuila, Mexico. She came to the United States with her husband, son, and daughters in the summer of 2005 with the hope and dream that her children would be successful. She began her adventure as a community health worker (promotora de salud) in 2009 when she completed the certification program at EPCC. Texas A&M opened up their doors and offered her a position at the Socorro Ramirez Community Center in Sparks, where she worked for two years. She met great people who taught her a lot, and she gained a lot of experience. Rosa worked with Dr. Cardenas doing H. Pylori exams. Through this job came the opportunity to become part of the ACCION program. Since 2012, Rosa has worked as a promotora de salud, giving wonderful service to the community. Rosa has educated a great amount of people, helping the community understand the importance of health screenings. She has enjoyed working in Hudspeth, Sierra Blanca and El Paso counties.

Rosa Maria Holguin completed her community health worker certification in 2007 from El Paso Community College. After receiving her certificate, she worked as a community health worker with the Texas A&M University colonias program in El Paso, providing education to the community about health, social resources, and the economy. She joined TTTUHSC El Paso in 2012 with the ACCION Program, where she provides education about colorectal cancer screening. During her spare time, she enjoys spending time with her family, listening to music, and dancing.

Sarai Martinez completed her Bachelor of Science in health promotion with a minor in community health in 2012. Sarai previously worked at Centro de Salud Familiar La Fe as a patient educator. She also worked as an outreach worker for the BEST program and Time to Get Vaccinated program at TTUHSC El Paso. She has been a research aide with the TTUHSC El Paso Department of Family and Community Medicine research division for three years. Sarai likes doing outside activities with her family and watching movies.

Bertha A. Medina was born in Cd. Juárez, Mexico, where she studied business administration. Bertha also obtained a certificate as a community health worker in El Paso. Before joining TTUHSC El Paso as an outreach worker in 2015, she worked in various businesses in Juárez and El Paso in secretarial and data entry positions. She is currently working in the breast cancer screening program after having previously worked on the HPV prevention and outreach research study. She enjoys spending her free time with her family and enjoys dancing and drawing.

Elizabeth Meza attended El Paso Community College, with a major in liberal arts. She completed the certificate program as a community health worker in 2006. Since then, she has held a variety of positions. She was previously employed by the Ysleta Independent School District after graduation, where she was a substitute teacher at Desertaire Elementary School for three years, but felt an urge to put her degree to full use. In 2009, she obtained a position with the El Paso chapter of AVANCE as an educator for both parents and their children. Elizabeth began working for TTUHSC El Paso in October of 2015. As an outreach worker, she provides help to the community and makes people aware of resources they did not know were available to them. Elizabeth says it has been very fulfilling to serve the El Paso area and looks forward to being with the institution and program for many years to come.

Bertha Ostos was born and raised in Cd. Chihuahua, Chihuahua, Mexico where she worked as a registered nurse. She came to the United States in 1992 with her husband and three small children. She is now a proud grandmother of seven, and they are her inspiration and motivation to live life to the fullest. Since she arrived in the U.S., her goal has been to help her community and work in the health field. She had been a volunteer at the Montana Vista Community Center (now La Fe Community Center), for three years, when in 1998 she was offered a promotora de salud position with Texas A&M University. During her 10-year tenure at Texas A&M, she received the promotora de salud certification and contributed greatly to the colonia neighborhoods in our region. This time was very important to her because it taught her how to reach out to the community, and she discovered the needs of our people, which inspired her to continue to work with more passion. In 2006, the Texas A&M colonias program was discontinued due to lack of funding, and shortly after her mother suffered a stroke. Due to this series of events, she took time off to care for her mother, but she started to get involved in the community again after her mother’s passing in 2009. It wasn’t long before she decided to recertify as a promotora de salud, completing the program in 2014. One year later, she came upon the opportunity of outreach worker at TTUHSC El Paso, and she feels very blessed to be a part of this great team. She is very grateful to the department leaders for giving her this opportunity, based on her 20 years of experience. Every day she spends as a community outreach worker is a day she gets to help members of our community, and she is extremely grateful and fulfilled.

Gabriel Nieves was born in Puerto Rico but raised in Ohio.  He grew up in Cleveland and is new to El Paso. His career began in working for nonprofit organizations in 1985 throughout the Cleveland area. He worked primarily with the Hispanic population as an Employment Counselor, Career Counselor, Case Manager and Family Interventionist, just to name a few of his community endeavors. He worked with high-risk youth populations, language barrier and mental health consumers. His background includes behavioral health and mental health, and he feels he has been blessed working with these populations throughout his career. He’s gained tremendous experience and learned that this is what he enjoys doing, meeting some wonderful teachers along the way and working with great personnel. In short, he enjoys working in the community “doing the most good” and feels TTUHSC El Paso's Accion program will be just that.

Jesse was born and raised across the border and spent much of his childhood in Juarez, Mexico, before moving to the United States in the early 1990’s. He is a first-generation college student who is extremely proud of his Mexican-American roots and sees himself as an example to his family. He is married and the proud father of two sons. Working within the community and making a difference is one of his many passions, along with his love for music.

Betty has gained much experience throughout her carrier in different fields that have led her to various settings and experiences. She earned a B.S. in Management from the University of Phoenix along with nearly completing a B.S. in Nursing from the University of Texas at El Paso, needing a few more hours. Her work experience has a wide range, with the majority of it focused on clinical research as a coordinator in just over 20 clinical trials to date in the therapeutic area of rheumatology and gastroenterology. She is fluent in both English and Spanish and traveling/sightseeing is her favorite hobby.