- Author: Kathy Keatley Garvey
Professor Joanna Chiu, vice chair of the department, was singled out for her outstanding graduate and professional mentoring, and Professor Diane Ullman, former chair of the department, for her stellar undergraduate teaching.
The Academic Senate minutes state:
"Professor Joanna Chiu is known for her ability to help students visualize and internalize abstract interactions that are invisible to the naked eye. Students and colleagues praise her desire to demystify pathways to success in science. She's admired for her compassion and dedication to students at all levels, whether they are visiting high school students, undergraduates, or graduate students. Her graduate students have landed jobs in academia, industry, and medicine, and they seek her counsel well into their professional lives. Professor Chiu has also created training programs and financial awards to increase diversity and inclusivity in her field."
"Professor Diane Ullman has provided superb teaching and mentoring for many years, not only in the Department of Entomology and Nematology but as a leader in the Science and Society program. She has brought art-science fusion alive in innovative ways. Her nominees and students rave about her deep dedication, care, and knowledge in all teaching interactions, as well as her overall commitment to student success. One student nominee summed it up best: "My experience in her course last spring was one that lifted my spirits, enriched my education, and strengthened my love for art and science during a time when it was difficult to feel positive about anything.”
The award packets called for a nomination letter, letters of support from students, curriculum vitae (including publications, research grants, and honors and awards), teaching activities, and student evaluations.
Chiu, a molecular geneticist and physiologist, joined the department in 2010 and has served as the vice chair of the department since 2016. She was nominated by medical entomologist-geneticist Geoffrey Attardo, assistant professor.
Attardo, a co-instructor and a guest lecturer in some of her classes, wrote: "Joanna is skilled at communicating complex/abstract topics. She has a clear and concise manner of delivering information which is essential when dealing with aspects of molecular biology/genetics/biochemistry. This is especially so for students with little to no background in these fields. The nature of these topics requires students to internalize the information and visualize abstract interactions invisible to the naked eye. I have observed (and in fact taken classes myself) where this type of information is presented in a dense and impenetrable lecture format with little to no interaction between the professor and the students."
Complex Subject Matter. Commenting on analysis of genomic variation, Attardo wrote: "The class covered the basics of genetic variation, techniques used to characterize/analyze this type of data and ways in which this data can be applied to applications such as taxonomy, evolutionary biology, and population dynamics. Joanna presented this complex subject matter in a stepwise manner using clear visual aids with each step being reinforced by real world examples from the literature. She further engaged the students with queries to interpret examples, ask questions and explore their understanding of the material to that point. Her strategy of presenting this information in small chunks followed by time for thought and personal interpretation is an excellent way to introduce these topics and give the students time to process/wrestle with the information internally before moving onto the next concept. I sat in on this session as this topic is somewhat of a weak spot for me and I found it extremely informative and enjoyable."
Graduate students Erin Taylor Kelly, Lindsey Mack, Christine Tabuloc and Yao Cai, and alumnus Kelly Hamby (now an associate professor/Extension specialist, Department of Entomology, University of Maryland) strongly supported the nomination.
"I consider Dr. Chiu's teaching and mentorship approach to be a model that I seek to emulate. Her lectures are famously clear and organized; I find myself returning to them long after classes are over for topic refreshers," Kelly wrote in part.
Encourages Us to Think Deeply. Mack praised her commitment to her students and her ability to relate course content to current research. "She encourages us to think deeply about course material to stimulate questions and acquire skills."
"What makes her so outstanding is her commitment to helping us improve as scientists and researchers and preparing us for our future career endeavors," wrote Tabuloc. "She advises me on how to be a more resilient scientist and gives me the opportunity to do outreach events where I talk about my science with the general public, teach workshops about writing in the sciences and the circadian clock, present my work at conferences, and attend workshops that increase my skillset. I have learned how to make the subject interesting to the audience and easy to understand."
"There is no final exam in the class," Cai related. "As a substitute, students are asked to write a two-page National Science Foundation research proposal and peer-review others' proposals. She encourages students to think actively, instead of just memorizing facts for the exams. Dr. Chiu knows what skills are the most critical in a certain stage of PhD training…critical thinking, scientific reading, scientific writing, presentation, time management, scientific rigor."
Office Always Open. Wrote Hamby: "Her office is always open to students, whether they are visiting high school students, undergraduates, or graduate students, her own students or someone else's. She carefully guides students throughout their experiments, directly providing technical training—side by side at the bench—while developing their critical thinking and communication skills. Joanna not only imparts excellent analytic and laboratory molecular skills to her students, but also commits to providing ongoing professional advice and development."
The students also lauded her commitment to improving diversity in the department and supporting stipend raises.
Professor Chiu is the co-administrator of the campuswide Research Scholars in Insect Biology, which aims to provide undergraduates with a closely mentored research experience in biology. A 2019-23 Chancellor's Fellow, she received the 2019 Physiology, Biochemistry and Toxicology Award from the Pacific Branch, Entomological Society of America. She holds a bachelor's degree in biology and music from Mount Holyoke College, Mass., and a doctorate in molecular genetics from New York University. She served as a postdoctoral fellow in chronobiology--molecular genetics and biochemistry, at the Center for Advanced Biotechnology and Medicine, Rutgers, the State University of New Jersey.
Professor Ullman, both an entomologist and an artist, received her bachelor of science degree in horticulture from the University of Arizona and her doctorate in entomology from UC Davis in 1985. She joined the UC Davis faculty in 1995 after serving as an associate professor of entomology at the University of Hawaii. Her credentials include: chair of the UC Davis Department of Entomology, 2004-2005; associate dean for undergraduate academic programs for the College of Agricultural and Environmental Sciences, 2005 to 2014; and co-founder and co-director of the UC Davis Art/Science Fusion Program, launched in September 2006.
A Fellow of both the American Association for the Advancement of Science (2014) and the Entomological Society of America (2011), Ullman was named the 2014 recipient of the ESA National Excellence in Teaching Award.
International Acclaim. UC Davis Distinguished Professor Jay Rosenheim, a fellow faculty member since 1994--and who has known Ullman since she was a doctoral student--wrote the letter of nomination. "I have seen in Diane the rare academic who places co-equal emphasis on her research program, which has given her international acclaim, and her teaching and mentorship. Diane cares for every student who comes into her classes and her laboratory, takes them under her wing, and helps them thrive. She cares deeply about the well-being of everyone she mentors, and it shows in everything she does."
Rosenheim noted that her commitment to mentorship motivated her to "create a nationwide mentorship program as part of a $3.75 million grant from the USDA, for which she was the lead principal investigator, to give undergraduate students a closely mentored opportunity to conduct individual research projects. This program (Vector Pathogen Educational Network or VPEN) trained 28 postdoctoral researchers and graduate students to be mentors, and then paired each with an undergraduate student researcher mentee."
Rosenheim praised her entomology class, ENT 001, "Art, Science and the World of Insects," which he described as "a unique and creative course, created by Diane, to bring together art and science. The class includes two hours of lecture each week plus a single three-hour “labudio” – i.e., a combination of a science laboratory and an art studio. The lectures cover the biology and ecology of insects, including their interactions with humans and their importance in human culture."
Creative and Effective Approach. "Her commitment to student success has motivated her since she joined our campus, and she has taken a creative and effective approach to teaching and mentorship that has magnified her impact beyond her own immediate students and mentee," Rosenheim noted. "She has trained graduate students and postdoctoral researchers to be more effective mentors themselves, and the success of VPEN and the Career Discovery Groups (an undergraduate mentoring program founded by Ullman with David Rizzo) will ensure that these efforts continue to bear fruit well into the future."
In a letter of support, undergraduate entomology student Kyle Elshoff, Class of 2024, described Professor Ullman as "one of the best instructors" he's ever had. "She has a love and passion for both art and science that is infectious and inspires further discussion and exploration by students outside of class."
Professor Ullman is committed to "helping us succeed," Elshoff related, "especially with the challenges presented by remote learning during a pandemic. For instance, despite being unable to work with us in-person to create art in the wonderfully named 'Labudio,' she still ensured that every student would be able to exercise their creativity and create a meaningful final artwork. She prepared and shipped each of us a box of watercolor supplies to use and keep, and she recorded watercolor video tutorials with a local artist so that we could familiarize ourselves with basic principles and techniques. I felt supported by these kind actions; it was reassuring to know that I had a professor who cared about me and who, right from the outset, was willing to go the extra mile for her students."
Elshoff concluded: "My experience in her ENT 001 course last spring was one that lifted my spirits, enriched my education, and strengthened my love for art and science during a time when it was difficult to feel positive about anything. More than just a professor, Dr. Ullman is someone who I feel comfortable reaching out to for advice and guidance as I move forward with entomology and art."
- Author: Kathy Keatley Garvey
In an event dedicated to science, 11 UC Davis museums and collections will showcase their displays:
- Arboretum and Public Garden
- Bee Haven
- Bohart Museum of Entomology
- Botanical Conservatory
- California Raptor Center
- Center for Plant Diversity
- Department of Anthropology Museum
- Museum of Wildlife and Fish Biology
- Nematode Collection
- Paleontology Collection
- Phaff Yeast Culture Collection
Scientists will be on hand to greet visitors and answer questions.
The always popular birds of prey from the California Raptor Center will include Swainson's hawks (Grasshopper and Whistler) and great-horned owls (Forrest and Luna), according to Julie Cotton, interim operations supervisor. "We most likely will also have our barn owl (Ember) and red-tailed hawk (Jack), but their appearances could be of limited duration."
In addition to the exhibits in the Conference Center, five museums or collections will offer tours. The UC Davis Bee Haven, a half-acre educational bee demonstration garden maintained and operated by the UC Davis Department of Entomology and Nematology, will offer tours at noon and 2 p.m., with a limit of 20 people per tour. "We'll focus on how best to observe and identify bees in the garden, as well as suggested bee plants that grow well in our area with low water," said Christine Casey, academic program management officer of the Bee Haven. No masks will be required in the garden, she said. The site is located next to the Harry H. Laidlaw Jr. Honey Bee Research Facility on Bee Biology Road.
The UC Davis Arboretum and Public Garden has scheduled two 30-45 minute tours, "Climate Ready Tree Project: Texas Tree Trials." Groups will leave the Conference Center at 11:30 a.m. and 1:30 p.m. "Join us at Biodiversity Day for a tour of the Arboretum and Public Garden's new Texas Tree Trial Research Grove!" invites Rachel Davis, GATEways horticulturist and museum scientist at the Arboretum and Public Garden. "Tag along and learn about what the Urban Tree Stewardship student intern team is doing to promote a resilient and climate-adapted tree canopy in the Sacramento Valley. Make sure to bring hats, good walking shoes, and a curious attitude!"
Tours are also planned by three other entities, with times and other information pending:
CrowdFund. Crowdfund projects for both the Biodiversity Museum Day and the Bee Haven are underway until 12:59 p.m., Feb. 28.
The Biodiversity Museum Day Crowdfund at https://bit.ly/3HPhSaA seeks $5000. Donors can be anonymous in name or contribution, or can donate in honor of someone, or in memory of a loved one. Contributions from $5 on up are welcome, said the two project managers Tabatha Yang, education and public outreach coordinator for the Bohart Museum of Entomology, and Rachel Davis, a GATEways horticulturist and museum scientist at the UC Davis Arboretum and Public Garden.
"Donations will not only help us sustain the free, in-person event, it will enable our student interns to take science outreach to a whole new level," they said. "The goal of our event is to connect people from all walks of life to science and the biodiversity surrounding them. All donors will be recognized on the Biodiversity Museum Day social media accounts with a shout-out post."
The Bee Haven CrowdFund at https://crowdfund.ucdavis.edu/project/29773 seeks $3000 to support classroom visits from low-income schools and youth group visits. "Our CrowdFund will provide funding to three Title I schools or affiliated youth groups that will cover the guided tour fee and transportation costs for up to 50 people (students, teachers, parents) to participate in a 90-minute field trip at the Bee Haven on the UC Davis campus," related Casey. "We will fund up to $1000 per school," she writes on the Crowdfund website. "Our unique outdoor learning adventure has been experienced by nearly 50,000 visitors since 2013."
"Participants will see and learn about the 200 plant and 80 bee species that occur at the Haven. They will safely catch and observe bees and participate in a grade-appropriate bee monitoring exercise that will introduce them to scientific research and create a memorable learning adventure about bees, plants, science, and the natural world. We'll also provide books for each school's library that can be used to extend program impact."
The UC Davis Biodiversity Museum Day is traditionally held on the Saturday of Presidents' Day weekend. However, last year's event was virtual, and this year's event is centrally located in an exposition. For more information, access the UC Davis Biodiversity Museum Day website and/or connect with Instagram, Twitter, and Facebook.
- Author: Kathy Keatley Garvey
A natural product from the dried root of a pea-family plant, potentially combined with an enzyme inhibitor discovered in the Bruce Hammock laboratory at the University of California, Davis, may provide hope in alleviating neuroinflammation in Parkinson's disease, an eight-member team of researchers from Dalian Medical University, China, and UC Davis announced today.
Their novel research, published in the current edition of the Proceedings of the National Academy of Sciences (PNAS), shows that a soluble epoxide hydrolase (sEH) inhibitor and kurarinone, a compound from the dried root of Sophora flavescens, reduced neuroinflammation in an animal model with Parkinson's disease (PD). The dried root, also known as kushen in Chinese, has been used for hundreds of years in traditional Chinese medicines.
“Traditional Chinese medicines play an immeasurable role in the treatment of all kinds of diseases,” said thelead researcher Cheng-Peng Sun, a Dalian Medical University associate professor who is partnering with the Hammock lab on the PD research. For the past 35 years, Hammock, a distinguished professor who holds a joint appointment with the Department of Entomology and Nematology and the UC Davis Comprehensive Cancer Center, has researched enzyme inhibitors that dramatically reduce inflammation, inflammatory pain and neuropathic pain.
“We investigated the neuroprotective effects of S. flavescens in Parkinson's disease based on the neuroinflammation,” Sun explained. “Our extensive studies indicated that kurarinone possesses several pharmacological effects, including anti-inflammatory and antioxidative activities.”
The research, titled “Kurarinone Alleviated Parkinson's Disease via Stabilization of Epoxyeicosatrienoic Acids in Animal Model (Mice),” may lead to an effective therapy for PD, a progressive neurogenerative or brain disorder which affects more than 10 million people worldwide, including a million in the United States, according to the Mayo Clinic. Most PD patients are 65 or over and most are men. There is no cure.
“Basically, kurarinone targets the soluble epoxide hydrolase (sEH), which is a key regulatory enzyme involved in the metabolism of fatty acids, and inhibitors of the sEH enzyme resolve neuroinflammation,” said Professor Hammock, corresponding author. “The enzyme regulates a newly studied class of natural chemical mediators, which in turn regulates inflammation, blood pressure and pain.”
“We have known for a number of years that the soluble epoxide hydrolase inhibitors, now in human safety trials, are active in reducing the development of Parkinson's disease in several rodent models,” Hammock said. “The evidence for this is quite strong, particular based on work of our longterm collaborator Kenji Hashimoto at Chiba University in Japan. Certainly, Parkinson's disease is one of our targets for the sEH inhibitors, but the regulatory path is slow and expensive. This path becomes much faster for a natural product, so the discovery of this natural product from Cheng-Peng's laboratory potentially offers relief to patients far faster than a classical pharmaceutical.”
“In addition to its use as a natural product for treating Parkinson's disease, kurarinone provides a new model for the design of still more active compounds to block the neuroinflammation associated with multiple neurodegenerative diseases where sEH inhibitors have shown efficacy in rodent models including Alzheimer's, autism, and other disorders,” Hammock said. “The fact that kurarinone binds in the sEH enzyme in an adjacent but non-identical site opens the door to new synthetic drugs for these diseases.”
Co-author Christophe Morisseau, a biochemist in the Hammock lab, performed the enzyme kinetics, demonstrating the potency of the compound and how it interacts with the enzyme. “This research is important in two ways,” he said. “In lay terms, it demonstrates the use of a natural compound to treat Parkinson's disease. Right now, there is no effective treatment for this disease, so this is pretty cool. And we show that the compound used has a novel mechanism of inhibiting sEH compared to the previous inhibitors published.”
UC Davis Health System neurologist and School of Medicine Professor Lin Zhang, who is known for his PD expertise (he was not involved in the study), praised the research as novel and “Although we now have multiple medications to manage the debilitating symptoms of Parkinson's disease, we still don't have a way to stop the progression of the disease, not to mention having a cure,” said Zhang, who treats PD patients. “The conventional wisdom believes the reason for that is that we have been only treating the symptoms, not the cause of the disease. One of the contributing causes, as evidenced recently, has been neuroinflammation.”
A common Parkinson model comes from mice treated with MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine). Tragically this deadly drug was discovered as an impurity in a recreational “This paper shows that when parkinsonian mice were treated with the natural product kurarinone, their Parkinson-like behaviors were significantly alleviated by attenuation of neurotoxicity,” Zhang said. “The same natural product was able to suppress sEH activities selectively so much so that neuroinflammation was markedly ameliorated. Furthermore, when the same models had their sEH gene knocked out, kurarinone did not provide additional protection against Parkinsonism.”
“This paper shows that kurarinone, a natural product, is able to alleviate Parkinson symptoms,” Zhang pointed out. “The mechanism for that has something to do with the fact that kurarinone targets soluble epoxide hydrolase (sEH) which mediates neuroinflammation. Products capable of inhibiting sEH like kurarinone can provide a novel, yet promising, mechanism to reduce neuroinflammation, subsequently treating neurodegenerative disorders including PD at its core.”
Added Zhang: “These findings presented in this paper help to solidify the candidacy of sEH as a key player of PD pathogenesis via neuroinflammation, underscoring the role of sEH inhibitors as a new class of anti-neuroinflammatory pharmaceuticals treating neurodegenerative disorders including PD.”
What's the next step?
“We hope that the natural herbal medicine will offer some relief from Parkinson's disease,” said Sun.
Added Morisseau: “We also hope to increase kurarinone levels in the plant and ensure that the extracts are nontoxic and effective. Possibly we can even find a food plant that is effective.”
Hammock lab researcher Sung Hee Hwang, an organic chemist, has been making small molecule inhibitors for Parkinson's disease, “and the crystal structure of sEH bound to kurarinone will be a great help to him,” Hammock said. “He has been working with Jogen Atone who is just finishing his doctorate in the UC Davis Pharmacology Toxicology program working on basic aspects of Parkinson's disease and environmental chemicals that may cause it.”
Sophora (the Arabic name for a pea-flowered tree) is a genus of about 45 species of evergreen trees and shrubs in the pea family, Fabaceae. The species are native to southern Asia, Australasia, various Pacific islands, western South America, the western United States, Florida and Puerto Rico. About fifteen of these species have a long history of use in traditional Chinese
“Now that we have a lead structure, we hope to screen related species for related compounds and efficacy,” Morisseau said.
“Parkinson's disease occurs when nerve cells in the basal ganglia, an area of the brain that controls movement, become impaired and/or die,” according to the National Institute on Aging (NIA). “Normally, these nerve cells, or neurons, produce an important brain chemical known as dopamine. When the neurons die or become impaired, they produce less dopamine, which causes the movement problems of Parkinson's. Scientists still do not know what causes cells that produce dopamine to die.”
“One clear risk factor for Parkinson's disease is age,” NIA says. “Although most people with Parkinson's first develop the disease at about age 60, about 5 to 10 percent of people with Parkinson's have ‘early-onset' disease, which begins before the age of 50. Early-onset forms of Parkinson's are often, but not always, inherited, and some forms have been linked to specific gene mutations.”
Hammock expressed hope that a variety of research pathways, such as the one resulting in kurarinone, “can lead to therapies, preventions and cures of Parkinson's disease and other neuroinflammatory problems associated with aging.”
Contact:
Bruce Hammock, bdhammock@ucdavis.edu
- Author: Kathy Keatley Garvey
His seminar, to be both in-person and virtual, begins at 4:10 p.m., Pacific Time in 122 Briggs Hall. The Zoom link is https://ucdavis.zoom.us/j/99515291076.
"From the moment of initial encounter with an insect herbivore, a suite of inducible plant defenses are triggered; however, the molecular mechanisms for recognition and response are not highly studied," Steinbrenner writes in his abstract. "Specific molecular patterns from insects can serve as elicitors of defense responses on host plants, but precise receptors mediating such responses have remained elusive. We recently identified a cell surface receptor, Inceptin Receptor (INR), which detects a set of ubiquitous peptide fragments found in the oral secretions of Lepidopteran larval herbivores. INR is specific to select legume species and may structure insect host range across this plant family. We hypothesize that INR serves as a recently evolved and highly potent mechanism to perceive a specific danger signal, above and beyond cues associated with generic tissue damage. I will discuss our recent transcriptiomic characterization of inceptin responses in bean and cowpea, highlighting strong anti-herbivore defense outputs which occur after inceptin treatment but not wounding alone. I will also compare plant responses to herbivory with well-characterized pathways mediating recognition of microbial pathogens."
Steinbrenner focuses his research on cell and molecular biology, genetics and genomics, and plant biology. He holds a bachelor of science degree in biology from Tufts University (2010) and a doctorate from UC Berkeley in plant biology (2015). He was awarded a Howard Hughes Medical Institute Postdoctoral Fellowship of $180,000 in 2016 and studied with Eric Schmelz at UC San Diego.
The Steinbrenner lab studies the molecular bases of plant immunity to pathogens and pests. "We are specifically interested in recognition and signaling functions of cell surface receptors and evolutionary processes driving novel immune specificity," he says on his website.
Steinbrenner served as the lead author of a paper published Nov. 23, 2021 in the Proceedings of the National Academy of Sciences on how cowpea plants detect that they're being eaten by caterpillars. In the article, A Receptor-Like Protein Mediates Plant Immune Responses to Herbivore-Associated Molecular Patterns, scientists from the University of Washington and UC San Diego reported that the cowpea plants harbor receptors on the surface of their cells that can detect a compound in caterpillar saliva and initiate anti-herbivore defenses.
"Despite chemical controls, crop yield losses to pests and disease generally range from 20-30 percent worldwide," Steinbrenner related in a University of Washington news release. "Yet many varieties are naturally resistant or immune to specific pests. Our findings are the first to identify an immune recognition mechanism that sounds the alarm against chewing insects.”
Wrote UW science writer James Urton: "The team showed that, in response to both leaf wounds and the presence of a protein fragment specific to caterpillar saliva, the cowpea's INR protein boosts the production of ethylene, a hormone that plants often produce in response to munching by herbivores and other types of environmental stress. The protein fragment in caterpillar spit that elicited this response, Vu-IN, is actually a fragment of a cowpea protein, which gets broken down by the caterpillar as it dines on cowpea leaves." (See full article.)
Nematologist Shahid Siddique, assistant professor, UC Davis Department of Entomology and Nematology, coordinates the Wednesday seminars. For any Zoom technical issues, contact him at ssiddique@ucdavis.edu.
- Author: Kathy Keatley Garvey
"Our CrowdFund will provide funding to three Title I schools or affiliated youth groups that will cover the guided tour fee and transportation costs for up to 50 people (students, teachers, parents) to participate in a 90-minute field trip at the Bee Haven on the UC Davis campus," announced Christine Casey, academic program management officer for the UC Davis Bee Haven, an educational bee demonstration garden maintained and operated by the UC Davis Department of Entomology and Nematology.
"Participants will see and learn about the 200 plant and 80 bee species that occur at the Haven. They will safely catch and observe bees and participate in a grade-appropriate bee monitoring exercise that will introduce them to scientific research and create a memorable learning adventure about bees, plants, science, and the natural world. We'll also provide books for each school's library that can be used to extend program impact." View Casey's YouTube video.
Casey serves as the Crowdfund leader. Assisting her are Haven volunteers Connie Alexich, Diane Kelly, and Barbara Heinsch.
The bee garden, located next to the Harry H. Laidlaw Jr. Honey Bee Research Facility on Bee Biology Road, is open daily from dawn to dusk except for Tuesdays (open at 10 a.m.) "so we can maintain physical distance during garden maintenance," Casey says.
The UC Davis Bee Haven was installed in the fall of 2009 during the interim department-chair term of Professor Lynn Kimsey, director of the Bohart Museum of Entomology. Art by the UC Davis Art-Science Fusion, co-directed and co-founded by Diane Ullman, professor and former chair, UC Davis Department of Entomology and Nematology, and Donna Billick of Davis, graces the garden. Billick, a self-described "rock artist, created the six-foot-long, 200-pound ceramic mosaic sculpture of a worker bee, "Miss Bee Haven," in 2010.
All contributions to support the fundraising project are welcome and appreciated. Access the CrowdFund site at https://crowdfund.ucdavis.edu/project/29773. As of 11 a.m. today (Feb. 17), donations amounted to $575. The project ends at 12:59 p.m., Feb. 28.