Infections Expert Witnesses

Infectious Diseases, Internal Medicine - COVID-19, nursing homes, long term care, sepsis, necrotizing fasciitis, infections, surgical site infections, infection control, antimicrobial stewardship, consulting, insurance, case review, medical malpractice, standards of care, sepsis, bacterial or viral infections, outbreak management

Ramzi Asfour, MD, is board certified in Infectious Diseases and Internal Medicine, and Assistant Clinical Professor of Medicine at the University of California San Francisco (UCSF). In addition to his 20+ years of extensive private practice, Dr Asfour has privileges at five California hospitals (Alameda County Medical Center, Alameda Hospital, Sutter Lakeside Hospital, Sutter Eden Medical Center, and Mammoth Hospital). Dr. Asfour has worked for the World Health Organization in Geneva in the HIV / AIDS department, developing training programs for doctors in HIV. In addition to his clinical practice, Dr Asfour also advises hospitals, skilled nursing facilities, schools and businesses on infection control, including outbreak control and COVID-19, and antimicrobial stewardship. Dr Asfour has experience working with both plaintiff and defense attorneys to provide clear, independent opinions on matters involving: Medical malpractice, standards of care, sepsis, necrotizing fasciiti...

Wound Care, Medical Management - bedsores, skin injuries, surgical wounds, burns, pressure ulcers, venous ulcers, hyperbaric oxygen, infections, nursing home, medical devices, telemedicine, scar, qui tam, medical necessity, fraud, patents, medical devices, medical director, decubitus ulcers, diabetic ulcers, regenerative medicine

Award-winning wound care physician in active clinical practice. Wound care clinical, safety ,and leadership experience in acute care, skilled nursing (nursing homes), rehabilitation, and home health settings. Certified Wound Specialist (CWS) with additional Board Certifications in Hyperbaric Medicine and Family Practice. Has served as the medical director of several wound programs. Over twenty years of medical necessity/utilization review and expert witness experience. Midwestern University Medical School faculty. Significant private equity, medical device, startup, and consulting experience. Undergraduate degree in aeronautical engineering, Rensselaer Polytechnic Institute. Deposition and trial experience in multiple states. Over 85,000 wound encounters. Key roles have included medical director oversight of several level 1 hospital trauma wound programs, 5 community hospital wound programs, and over 15 SNF/LTACHs. Co-implemented one of the largest wound care/hyperbaric clinical de...

Hospitalist, Internal Medicine - Hospital Medicine, Adult Hospital Medicine, Hospital Inpatient, Infections, Pneumonia, Electrolyte Abnormalities, Hypertension, Diabetes, Heart Disease, Sepsis, Falls, Stroke, Bedsores

I am a practicing hospitalist with over 18 years of patient care experience since completing a residency in the specialty of Internal Medicine at the University of Utah Health Sciences Center in Salt Lake City, UT. In addition, I hold a Doctor of Medicine degree from Eastern Virginia Medical School in Norfolk, VA. Before this, I completed a Bachelor of Science in Biology at The College of William and Mary in Williamsburg, VA. I am board certified in the specialty of Internal Medicine by the American Board of Internal Medicine. My initial certification was in 2004, and I recertified in 2014 with a Focused Practice in Hospital Medicine. In 2016, I was selected as a Fellow of the American College of Physicians. I have served as an outside medical consultant for the Arizona Medical Board since 2016 and an outside medical consultant for the Arizona Board of Osteopathic Medical Examiners since 2018. I am currently licensed to practice medicine in Arizona and Montana.

Infectious Diseases, Internal Medicine - COVID-19, nursing homes, long term care, sepsis, necrotizing fasciitis, infections, surgical site infections, infection control, antimicrobial stewardship, consulting, insurance, case review, medical malpractice, standards of care, sepsis, bacterial or viral infections, outbreak management

Ramzi Asfour, MD, is board certified in Infectious Diseases and Internal Medicine, and Assistant Clinical Professor of Medicine at the University of California San Francisco (UCSF). In addition to his 20+ years of extensive private practice, Dr Asfour has privileges at five California hospitals (Alameda County Medical Center, Alameda Hospital, Sutter Lakeside Hospital, Sutter Eden Medical Center, and Mammoth Hospital). Dr. Asfour has worked for the World Health Organization in Geneva in the HIV / AIDS department, developing training programs for doctors in HIV. In addition to his clinical practice, Dr Asfour also advises hospitals, skilled nursing facilities, schools and businesses on infection control, including outbreak control and COVID-19, and antimicrobial stewardship. Dr Asfour has experience working with both plaintiff and defense attorneys to provide clear, independent opinions on matters involving: Medical malpractice, standards of care, sepsis, necrotizing fasciiti...

Pediatrics, General Practice - Infants, Children, Teens, General Pediatrics, Primary Care, Outpatient, Newborns, Standard of Care, Evidence-Based Medicine, Development, Behavior, Failure to Thrive, Nutrition, Vaccines, child abuse, neglect, Allergies, Asthma, Obesity, Infections, Rashes, Telemedicine

Dr. Jennie W. Gary is board-certified in Pediatrics and is a Fellow of the American Academy of Pediatrics. She works at a busy outpatient community pediatrics clinic as a general pediatrician, where she sees thousands of patients annually. She also teaches and supervises pediatric residents on a bi-weekly basis. She participates in weekly CME activities and practices standard of care, evidence-based medicine according to American Academy of Pediatrics guidelines.

Infectious Diseases - Infections in all medical Specialties, Sepsis, HIV, AIDS, hepatitis, food poisoning, pneumonia, orthopedic infections, meningitis, surgical infections, wound infections, urinary tract infections, endocarditis, abdominal infections, abscess, septic arthritis, infection control

Clinical Infectious Disease Specialist in active practice; Extensive experience in medico-legal review for both plaintiffs and defense; Board Certified in Infectious Disease; HIV Specialist; Medical Director of Infection Prevention and Control at two Northern California Hospitals; Chief of Infectious Disease at Summit Medical Center. See CV for further details.

Hospitalist, Internal Medicine - Hospitalist, Hospital Medicine, Internal Medicine, Infections, Pneumonia, Electrolyte abnormalities, Hypertension, Diabetes, Heart Disease, Sepsis, Shock, Falls, Stroke, Medical Necessity, InterQual, Milliman Care Guidelines (MCG)

Dr. McIlraith received his BS, and MD from the University of Wisconsin; and completed Internal Medicine Residency at the McGaw Medical Center of Northwestern University in 1999. In 2000, he was made the head of the hospitalist division in the South Sacramento Kaiser Permanente. He became the Chairman of Hospital Medicine at Mercy Medical Group in 2004. In the subsequent 12 years he grew the department from 12 to 84 hospitalists. He was elected to the MMG board of directors in 2009, and served as Treasurer from 2011 through 2016. Dr. McIlraith has been providing expert opinion services to defense and plaintiff clients since 2011. He has served on the The Doctors Company Hospital Medicine Advisory Board. Dr. McIlraith joined NAIP (now SHM) as a charter member in 1998 and has been active ever since. He was in the inaugural FHM class in 2009, the inaugural SFHM class in 2010, and the inaugural CLHM class in 2013. He was the 2016 recipient of the SHM Award of Excellence, and is...

Nursing Homes - Nursing Home, SNF, Skilled Nursing Facility, Hospice, Infections, Palliative Care, Geriatrics, Dementia, Neglect, Goals of care, Delirium, Polypharmacy, Alzheimer's, COVID, Bed Sores, Pressure Ulcers, Medical Malpractice, Standards of Care, Hypertension, Diabetes, Heart Disease, long-term care

Dr. Andrew Ng is board certified in Internal Medicine. He began practice working as a hospitalist in the acute care setting both in Michigan and then in California. After starting part-time work caring for patients in the skilled nursing environment, Dr. Ng transitioned to full-time practice in Skilled Nursing Facilities (SNF) and long-term care settings. Dr. Ng specializes in short-term and long-term care for patients who reside in SNFs. He is aware of the intricacies involved in providing care in this setting and appropriate standards of care. He can provide efficient case reviews in all aspects of nursing home care. Specialty areas include; COVID-19, nursing homes, long-term care, medical negligence, elder abuse/neglect, nursing home falls, physical and chemical restraints, elopement, dementia, memory care, geriatric polypharmacy, bedsores (pressure wounds or pressure ulcers), nursing home infections (MRSA, VRE), dehydration, geriatrics, head trauma, accidental and suspected no...

Critical Care Medicine, Critical Care Surgery - Surgical Critical Care, ICU Medicine, Shock, Sepsis, Resuscitation, Cardiac arrest, Emergency airway, Intubation, Respiratory failure, COVID, Pneumonia, Pulmonary embolism (PE), Central line, Procedural complications, Infections, Tele-ICU, Medical records review

Dual board certified in General Surgery and Surgical Critical Care by the American Board of Surgery with additional certification obtained in Bariatrics Surgery. In active clinical practice focusing on Surgical Critical Care and ICU Medicine. Experienced as an ICU Medical Director as well as with quality improvement metrics and clinical optimization. I take care of general Medical and Surgical Critical Care patients in a variety of settings including academic, community, rural and tele-ICU. Able to provide objective expert opinions on medical malpractice cases. CV available upon request.

Nursing Homes - Nursing Home, SNF, Skilled Nursing Facility, Hospice, Infections, Palliative Care, Geriatrics, Dementia, Neglect, Goals of care, Delirium, Polypharmacy, Alzheimer's, COVID, Bed Sores, Pressure Ulcers, Medical Malpractice, Standards of Care, Hypertension, Diabetes, Heart Disease, long-term care

Dr. Taher is board-certified in Internal Medicine. He completed his residency in Internal Medicine at the Alameda County Medical Center in Oakland, California, and a Rheumatology Fellowship at the University of California, San Francisco. His practice focuses mainly on skilled nursing facilities, caring for adult geriatric patients, including patients in sub-acute facilities who are ventilator-dependent. He has extensive experience in all aspects of nursing home care, including fall prevention, pain management, treatment of diabetes, hypertension, stroke, end-of-life care, common infections, and policies and procedures related to skilled nursing homes. He is currently the Medical Director at three San Francisco Bay Area skilled nursing facilities, one of which includes a sub-acute unit. He also serves as a hospice medical director. Specialty areas include; COVID-19, nursing homes, long-term care, medical negligence, elder abuse/neglect, nursing home falls, physical and chemical res...

Emergency Medicine - Failure to Diagnose, Pain and suffering, Trauma, Motor vehicle accident, Heart Attack, Myocardial Infarction, MI, Aortic Dissection, Pulmonary Embolism, PE, Aortic Aneurysm, Appendicitis, Ischemic Bowel, Stroke, TIA, Subarachnoid Hemorrhage, Cauda Equina Syndrome, Sepsis, Pneumonia, Infections

Hi, I’m Dr. Glenn Birnbaum, a residency-trained, board-certified Emergency Medicine Specialist and a fellow of the American College of Emergency Physicians. In addition to over 30 years’ experience in clinical practice as an emergency physician, I have extensive additional experience as core faculty for an emergency medicine residency training program, leadership of several high-volume, high-acuity emergency departments, and leadership of a large regional Emergency Physician group. I specialize in Emergency Room Failure to Diagnose cases and have assisted attorneys in 50-100 personal injury and medical malpractice cases, including frequent trial and deposition testimony in federal court and state courts nationwide. As an emergency medicine expert, I diligently review the facts of the matter at hand, identify all the relevant issues, and provide an extensive analysis of the matter. Hallmarks of my work as an expert include: clear, consistent, well-supported opinions, explanation ...

Medical Management, Risk Management - Healthcare risk management, patient safety, patient falls, medical errors, surgical errors, medication errors, delay in treatment, credentialing, root cause analysis, healthcare handoffs, hospital acquired conditions, infections, pressure ulcers, nursing home abuse

Patient Safety Expert Healthcare Risk Manager Keynote Speaker Arnold Mackles, MD, MBA is a nationally recognized expert on Patient Safety. The mission of Dr. Mackles’ healthcare career has been to provide access to the highest quality care; first, during his 23 years of practice as a neonatal physician and then, for the past 15 years, as a National Patient Safety Expert in all areas of medical practice. Dr. Mackles’ specific areas of expertise include: Prevention of Medical Errors, Risk Management, Healthcare Performance Improvement Strategies, Creating / Maintaining a Culture of Patient Safety Excellence, Healthcare Communication Protocols, Safe and Accurate Medication Delivery, Root Cause Analysis, Healthcare Technology, Medical Documentation, and Patient Safety in Hospitals. He places a strong focus on systemic problems inherent within organizations and with individual providers that result in adverse patient outcomes. Dr. Mackles plays many roles within the Healthcare space ...

Urgent Care Medicine, Family Medicine - Urgent Care Standard of Care, Urgent Care Malpractice, Nurse Practitioner Supervision, Physician Assistant Supervision, Wrongful Death, Chest Pain, Abdominal Pain, Headaches, Fractures,Orthopedic injuries, Foreign Bodies, Infections, Pediatrics,urgent care medicine

Dr. Pick received his medical degree from the University of the Witwatersrand in Johannesburg, South Africa. He is board certified in Family Medicine and is a fellow of the American Academy of Family Physicians.In addition he is board certified in Urgent Care Medicine. He completed his residency at the University of Miami, Jackson Memorial Hospital where he was Chief Resident. Dr. Pick has practiced urgent care medicine for over twenty years. He is a founding member of the Board of Certification in Urgent Care Medicine and a founding board member of the Urgent Care College of Physicians.

Urgent Care Medicine, Emergency Medicine - trauma, stroke, heart attack, myocardial infarction, MI, pulmonary embolism, PE, sepsis, appendicitis, airway management, internal medicine, head injury, concussion, epidural abscess, foreign body removal, chest pain, wound care, infections, abdominal pain, testicular torsion, medical management

Emergency Medicine Physician in active clinical practice. 30+ years of clinical experience in both Emergency Room and Urgent Care settings. Holder of 2 US Medical Device Patents, specializing in performance safety in foreign body removal, measuring wound site damage, and suturing.

Internal Medicine, Document Examination - Delayed Diagnosis, Failure to Diagnose, Failure to Refer, Medication Errors, Lab Reporting, Cardiovascular Risk Factors, Pulmonary Embolism, Deep Venous Thrombosis, COVID-19, Supervision of Physician Extenders, Hypertension, Cancer Screening, Infections, Complications, Sepsis, Detailed Chart Review

Award-winning, Harvard-trained primary care physician. Extensive teaching experience: Emory Faculty (2001-Present), Former Harvard Faculty. Fellowship trained. Active clinical practice.

Emergency Medicine, Emergency Medical Toxicology - Stroke, sepsis, myocardial infarction, infections, trauma, medication side effects, drug testing, alcohol issues, intoxication, prison and jail medicine

I am Board-Certified in Internal Medicine as well, yet have exclusively practiced Emergency Medicine for the past 35 years, first in a county hospital setting, followed by working in a few private hospitals, where I practice presently. I am Board -Certified in Emergency Medicine since 1988 and have been recertified every 10 years since then, with the latest coming just two months ago. In addition, I have been Board-Certified in Medical Toxicology.

Phlebotomy, Laboratories & Testing - phlebotomist, venipuncture, blood work, blood test, specimen collection, nerve injury, infections, EHR, electronic health records, heplock, bruising, swelling, clots, bleeding, infiltration, arterial puncture, allergies, fainting, extravasation, petechiae, haemoconcentration, iatrogenic anemia

Physician Assistant, Orthopedic Surgery - Physician Assistant, PA, Midlevel, Orthopedics, Surgery, Trauma, Spine, Joint replacement, fracture, sports medicine, arthroscopy, foot and ankle, osteoporosis, revision surgery, cast, splint, infections, epidural abscess, pain management, narcotics, injections, preoperative, postoperative, EMR

I have been a Physician Assistant (PA) for 23 years. I have worked in primary care, school-based health, urgent care, pediatric intensive care, outpatient orthopedics and orthopedic surgery. I have been an expert witness for 5 years. I have extensive experience as a PA, most recently in all aspects of orthopedics and orthopedic surgery. My orthopedic experience includes non-operative care and operative care as first assistant for patients with complex conditions involving the spine, neck, hand and extremities, joints, total joints and revision joints, injections, casting, wound care, perioperative care, narcotic and non-narcotic pain management, trauma and fractures. I have rounded on thousands of hospital patients for a variety of operative and non-operative orthopedic conditions; managing their pain, wellness, expectations, anticoagulation therapy, wound and dressing care, antibiotics, hospital and surgical complications, and discharge needs. I am a leader in electronic medical...

Infectious Diseases, Internal Medicine - COVID-19, nursing homes, long term care, sepsis, necrotizing fasciitis, infections, surgical site infections, infection control, antimicrobial stewardship, consulting, insurance, case review, medical malpractice, standards of care, sepsis, bacterial or viral infections, outbreak management

Ramzi Asfour, MD, is board certified in Infectious Diseases and Internal Medicine, and Assistant Clinical Professor of Medicine at the University of California San Francisco (UCSF). In addition to his 20+ years of extensive private practice, Dr Asfour has privileges at five California hospitals (Alameda County Medical Center, Alameda Hospital, Sutter Lakeside Hospital, Sutter Eden Medical Center, and Mammoth Hospital). Dr. Asfour has worked for the World Health Organization in Geneva in the HIV / AIDS department, developing training programs for doctors in HIV. In addition to his clinical practice, Dr Asfour also advises hospitals, skilled nursing facilities, schools and businesses on infection control, including outbreak control and COVID-19, and antimicrobial stewardship. Dr Asfour has experience working with both plaintiff and defense attorneys to provide clear, independent opinions on matters involving: Medical malpractice, standards of care, sepsis, necrotizing fasciiti...

Emergency Medicine - Failure to Diagnose, Pain and suffering, Trauma, Motor vehicle accident, Heart Attack, Myocardial Infarction, MI, Aortic Dissection, Pulmonary Embolism, PE, Aortic Aneurysm, Appendicitis, Ischemic Bowel, Stroke, TIA, Subarachnoid Hemorrhage, Cauda Equina Syndrome, Sepsis, Pneumonia, Infections

Hi, I’m Dr. Glenn Birnbaum, a residency-trained, board-certified Emergency Medicine Specialist and a fellow of the American College of Emergency Physicians. In addition to over 30 years’ experience in clinical practice as an emergency physician, I have extensive additional experience as core faculty for an emergency medicine residency training program, leadership of several high-volume, high-acuity emergency departments, and leadership of a large regional Emergency Physician group. I specialize in Emergency Room Failure to Diagnose cases and have assisted attorneys in 50-100 personal injury and medical malpractice cases, including frequent trial and deposition testimony in federal court and state courts nationwide. As an emergency medicine expert, I diligently review the facts of the matter at hand, identify all the relevant issues, and provide an extensive analysis of the matter. Hallmarks of my work as an expert include: clear, consistent, well-supported opinions, explanation ...

Hospitalist, Internal Medicine - Hospital Medicine, Infections, Pneumonia, Electrolyte Abnormalities, Hypertension, Diabetes, Heart Disease, Sepsis, Falls, Stroke, Thromboembolic phenomena, gastrointestinal bleeding, chronic obstructive lung disease, congestive heart failure, Renal diseases, inflamatory bowel disease, oncology

I am an internist with over 15 years of clinical experience in the hospitalist medicine as well as ambulatory care. I am board certified in the Internal Medicine and Focused Hospital Medicine Practice. I had started my expert witness practice in 2009. Since then I have reviewed and generated reports of a variety of clinical cases on the side of plaintiffs, as well as defendants. I have also testified in depositions.

Emergency Medicine - Myocardial Infarction, Pulmonary Embolism, Critical Care, Stroke, Sepsis, Foreign Bodies, Fractures, Infections, Cardiac Arrest, Appendicitis, Airway Management, Urgent Care, PA & NP Supervision, Abdominal Pain, Abdominal Pain, Adult and Pediatric Cases.

I am a residency trained, board certified emergency medicine attending physician at a suburban emergency department. As the Associate Director of Emergency Services I assist with the management and leadership of the emergency department in addition to seeing patients. My duties include facilitating departmental policies & procedures, performance improvement and quality measures in the ED. I am published in the field of Emergency Medicine. I have prior experience performing medical expert consulting on case reviews with other law firms, medical consulting with a large consulting group and have court room experience.

Family Medicine, General Practice - Primary Care, Urgent Care, Preventative Medicine, Standard of Care, Pediatrics, Diabetes, Cancer Screening, Failure to Diagnose, Adolescent Health Care, Chest Pain, Infections, Gynecology

Dr. Gully is board certified in Family Medicine, currently practicing full-time as a Primary Care Physician, including care through telemedicine. In addition to treating patients he also supervises Nurse Practitioners and medical students. Prior to this he practiced in both Urgent Care Centers and Hospital settings. He earned an MD from the University of Cincinnati and completed residency in Chicago. Dr. Gully has recent experience in cases involving failure to diagnose, cancer screening, anticoagulation therapy, orthopedics, and morbidity following inpatient and outpatient surgery. He has been lauded for his written and oral communication skills, as well as poise during testimony.

Pediatrics - General pediatrics, General Pediatric care, Pediatric Standard of Care, Pediatric expert, Community pediatrics, Outpatient pediatrics, Board Certified, Newborn, infant, adolescent, infections, hip dysplasia, respiratory illness, Pediatric emergencies, documentation, nursery, pediatric expert

Dr. Herschel Lessin has been a full-time practicing Pediatrician since 1982 and has served as an expert witness in Pediatric malpractice litigation since 1987, working for both plaintiff and defense. Trained at Stanford and Yale, Dr. Lessin has experience in case review as well as both deposition and trial testimony. He a founding member and Vice President of one of the larger US single specialty Pediatric practices with 8 locations and 26 clinicians, His practice includes children from birth through college. Dr. Lessin is active on a national policy level, having been co-lead author on several American Academy of Pediatrics policy statements and technical reports, as well as being a member of the authoring committee on several others. He is co-editor of the 2019 AAP ADHD Toolkit. He reviews a majority of AAP policy statements making comments for possible revision as needed. He has been a member of the Committee on Practice/Ambulatory Medicine and the Payer Advocacy Advisory Commit...

Pediatrics, General Practice - Infants, Children, Adolescents, General Pediatrics, Primary Care, Newborns, Standard of Care, Evidence-Based Medicine, Development, Behavior, Failure to Thrive, Nutrition, Vaccines, Sexual/child abuse, neglect, Allergies, Asthma, Obesity, Infections, Rashes, Telemedicine, ADHD

Dr. Carey C. Williams is board-certified in Pediatrics and is a Fellow of the American Academy of Pediatrics. She works at a large suburban outpatient pediatrics clinic which serves 16,000+ patients from birth to 19 years of age. As a general pediatrician, she sees thousands of patients annually for acute and preventive care, and regularly rounds in the newborn nursery. She serves as lead physician for clinic- and community-based quality improvement initiatives, participates in regular CME activities, and practices evidence-based medicine according to American Academy of Pediatrics guidelines. She also teaches and supervises medical students on a regular basis.

Family Medicine, General Practice - Primary Care, Urgent Care, Preventative Medicine, Standard of Care, Pediatrics, Diabetes, Cancer Screening, Failure to Diagnose, Adolescent Health Care, Chest Pain, Infections, Gynecology

Dr. Gully is board certified in Family Medicine, currently practicing full-time as a Primary Care Physician, including care through telemedicine. In addition to treating patients he also supervises Nurse Practitioners and medical students. Prior to this he practiced in both Urgent Care Centers and Hospital settings. He earned an MD from the University of Cincinnati and completed residency in Chicago. Dr. Gully has recent experience in cases involving failure to diagnose, cancer screening, anticoagulation therapy, orthopedics, and morbidity following inpatient and outpatient surgery. He has been lauded for his written and oral communication skills, as well as poise during testimony.

Emergency Medicine - Failure to Diagnose, Pain and suffering, Trauma, Motor vehicle accident, Heart Attack, Myocardial Infarction, MI, Aortic Dissection, Pulmonary Embolism, PE, Aortic Aneurysm, Appendicitis, Ischemic Bowel, Stroke, TIA, Subarachnoid Hemorrhage, Cauda Equina Syndrome, Sepsis, Pneumonia, Infections

Hi, I’m Dr. Glenn Birnbaum, a residency-trained, board-certified Emergency Medicine Specialist and a fellow of the American College of Emergency Physicians. In addition to over 30 years’ experience in clinical practice as an emergency physician, I have extensive additional experience as core faculty for an emergency medicine residency training program, leadership of several high-volume, high-acuity emergency departments, and leadership of a large regional Emergency Physician group. I specialize in Emergency Room Failure to Diagnose cases and have assisted attorneys in 50-100 personal injury and medical malpractice cases, including frequent trial and deposition testimony in federal court and state courts nationwide. As an emergency medicine expert, I diligently review the facts of the matter at hand, identify all the relevant issues, and provide an extensive analysis of the matter. Hallmarks of my work as an expert include: clear, consistent, well-supported opinions, explanation ...