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Open Access Publications from the University of California

The Berkeley Research Impact Initiative (BRII) provides funding to Berkeley authors (current faculty members, post-docs, graduate students, researchers) and publishers (Centers, Organized Research Units, and
Departments) to make their publications free to all readers immediately upon publication. The purpose of the BRII program is to foster broad public access to the work of Berkeley scholars by encouraging the Berkeley
community to take advantage of open access (OA) publishing opportunities. For more information about the program see the BRII website:

Transmission Design and Analysis for Large-Scale Offshore Wind Energy Development


The offshore wind resource is very large in many coastal regions, over 80,000 MW capacity in the region studied here. However, the resource cannot be utilized unless distant offshore wind generation can be effectively collected and brought to shore. Based on extensive oceanographic, environmental, and shipping data, a realistic wind energy deployment layout is designed with 160 wind power plants each 500 MW. The power collection and transmission infrastructure required to bring this power to shore and connect it to the electricity grid is designed and analyzed. Three types of connection to shore are compared; high voltage AC to the nearest onshore point of interconnection (POI), high voltage DC with voltage-source converter (HVDC-VSC) to the nearest onshore POI, and connecting to an offshore HVDC backbone running parallel to shore that interconnects multiple wind power plants and multiple POIs ashore. The electrical transmission losses are estimated step by step from the wind turbines to the POI. The results show that such a large system can be built with existing technology in near-load resources, and that losses in the HVDC-VSC systems are approximately 1%-2% lower than that in the AC system for a distance about 120 km from shore.

Phenotypic and genetic diversity in aposematic Malagasy poison frogs (genus Mantella )


Intraspecific color variation has long fascinated evolutionary biologists. In species with bright warning coloration, phenotypic diversity is particularly compelling because many factors, including natural and sexual selection, contribute to intraspecific variation. To better understand the causes of dramatic phenotypic variation in Malagasy poison frogs, we quantified genetic structure and color and pattern variation across three closely related species, Mantella aurantiaca, Mantella crocea, and Mantella milotympanum. Although our restriction site‐associated DNA (RAD) sequencing approach identified clear genetic clusters, they do not align with current species designations, which has important conservation implications for these imperiled frogs. Moreover, our results suggest that levels of intraspecific color variation within this group have been overestimated, while species diversity has been underestimated. Within major genetic clusters, we observed distinct patterns of variation including: populations that are phenotypically similar yet genetically distinct, populations where phenotypic and genetic breaks coincide, and populations that are genetically similar but have high levels of within‐population phenotypic variation. We also detected admixture between two of the major genetic clusters. Our study suggests that several mechanisms—including hybridization, selection, and drift—are contributing to phenotypic diversity. Ultimately, our work underscores the need for a reevaluation of how polymorphic and polytypic populations and species are classified, especially in aposematic organisms.

Effectiveness of a Multimodal Digital Psychotherapy Platform for Adult Depression: A Naturalistic Feasibility Study


Background: Although psychotherapy is one of the most efficacious and effective treatments for depression, limited accessibility to trained providers markedly limits access to care. In an attempt to overcome this obstacle, several platforms seeking to provide these services using digital modalities (eg, video, text, and chat) have been developed. However, the use of these modalities individually poses barriers to intervention access and acceptability. Multimodal platforms, comprising those that allow users to select from a number of available modalities, may be able to provide a solution to these concerns.

Objective: We aimed to investigate the preliminary effectiveness of providing psychotherapy through a multimodal digital psychotherapy platform. In addition, we aimed to examine differential responses to intervention by gender, self-reported physical health status, and self-reported financial status, as well as how prior exposure to traditional face-to-face psychotherapy affected the effectiveness of a multimodal digital psychotherapy intervention. Finally, we aimed to examine the dose-response effect.

Methods: Data were collected from a total of 318 active users of BetterHelp, a multimodal digital psychotherapy platform. Data on physical health status, financial status, and prior exposure to psychotherapy were obtained using self-report measures. Effectiveness was determined by the extent of symptom severity change, which was measured using the Patient Health Questionnaire at Time 1 (time of enrollment) and Time 2 (3 months after enrollment). Intervention dosage was measured as the sum of individual therapist-user interactions across modalities.

Results: Depression symptom severity was significantly reduced after the use of the multimodal digital psychotherapy intervention (P<.001). Individuals without prior traditional psychotherapy experience revealed increased improvement after intervention (P=.006). We found no significant dose-response effect of therapy, nor significant differences in outcomes across gender, self-reported financial status, and self-reported physical health status.

Conclusions: Users of BetterHelp experienced significantly reduced depression symptom severity after engaging with the platform. Study findings suggest that this intervention is equally effective across gender, self-reported financial status, and self-reported physical health status and particularly effective for individuals without a history of psychotherapy. Overall, study results suggest that multimodal digital psychotherapy is a potentially effective treatment for adult depression; nevertheless, experimental trials are needed. We discuss directions for future research.

Open-source food: Nutrition, toxicology, and availability of wild edible greens in the East Bay



Foraged leafy greens are consumed around the globe, including in urban areas, and may play a larger role when food is scarce or expensive. It is thus important to assess the safety and nutritional value of wild greens foraged in urban environments.


Field observations, soil tests, and nutritional and toxicology tests on plant tissue were conducted for three sites, each roughly 9 square blocks, in disadvantaged neighborhoods in the East San Francisco Bay Area in 2014–2015. The sites included mixed-use areas and areas with high vehicle traffic.


Edible wild greens were abundant, even during record droughts. Soil at some survey sites had elevated concentrations of lead and cadmium, but tissue tests suggest that rinsed greens of the tested species are safe to eat. Daily consumption of standard servings comprise less than the EPA reference doses of lead, cadmium, and other heavy metals. Pesticides, glyphosate, and PCBs were below detection limits. The nutrient density of 6 abundant species compared favorably to that of the most nutritious domesticated leafy greens.


Wild edible greens harvested in industrial, mixed-use, and high-traffic urban areas in the San Francisco East Bay area are abundant and highly nutritious. Even grown in soils with elevated levels of heavy metals, tested species were safe to eat after rinsing in tap water. This does not mean that all edible greens growing in contaminated soil are safe to eat—tests on more species, in more locations, and over a broader range of soil chemistry are needed to determine what is generally safe and what is not. But it does suggest that wild greens could contribute to nutrition, food security, and sustainability in urban ecosystems. Current laws, regulations, and public-health guidance that forbid or discourage foraging on public lands, including urban areas, should be revisited.

CRISPR-Cas9 interrogation of a putative fetal globin repressor in human erythroid cells


Sickle Cell Disease and ß-thalassemia, which are caused by defective or deficient adult ß-globin (HBB) respectively, are the most common serious genetic blood diseases in the world. Persistent expression of the fetal ß-like globin, also known as ?-globin, can ameliorate both disorders by serving in place of the adult ß-globin as a part of the fetal hemoglobin tetramer (HbF). Here we use CRISPR-Cas9 gene editing to explore a potential ?-globin silencer region upstream of the δ-globin gene identified by comparison of naturally-occurring deletion mutations associated with up-regulated ?-globin. We find that deletion of a 1.7 kb consensus element or select 350 bp sub-regions from bulk populations of cells increases levels of HbF. Screening of individual sgRNAs in one sub-region revealed three single guides that caused increases in ?-globin expression. Deletion of the 1.7 kb region in HUDEP-2 clonal sublines, and in colonies derived from CD34+ hematopoietic stem/progenitor cells (HSPCs), does not cause significant up-regulation of ?-globin. These data suggest that the 1.7 kb region is not an autonomous ?-globin silencer, and thus by itself is not a suitable therapeutic target for gene editing treatment of ß-hemoglobinopathies.

The Atlantic blue crab Callinectes sapidus Rathbun, 1896 expands its non-native distribution into the Ria Formosa lagoon and the Guadiana estuary (SW-Iberian Peninsula, Europe)


The Atlantic blue crab Callinectes sapidus Rathbun, 1896 is native in the western Atlantic, however it is a non-indigenous species across Europe since 1900, among other world regions. In this paper, we report the first occurrences of this species in the Ria Formosa lagoon and in the Guadiana estuary (SW-Iberian Peninsula, Europe) which occurred in 2016 and July 2017, respectively. We hypothesize that the introduction of this species into these ecosystems might be due to the expansion of the Guadalquivir estuary population through natural processes (larval advection, active movement), or due to unintended introduction events after being transported aboard fishing boats, or, less likely, through ballast water. Changes in Guadiana’s river flow after the construction of the Alqueva dam might also explain the presence of another non-indigenous species in the Guadiana estuary. The hypotheses presented, regarding the introduction of the Atlantic blue crab into these ecosystems and of its co-occurrence with other decapod species, are framed in a broader context to serve as a future research framework. The use of the Atlantic blue crab as a new fishing resource is also proposed, namely if it is to be used exclusively by local communities and if no deleterious impacts upon other fisheries and the ecosystem occur from this new fishery.

Bacterial Contamination of Drinking Water in Guadalajara, Mexico


In many regions where drinking water supply is intermittent and unreliable, households adapt by storing water in cisterns or rooftop tanks. Both intermittent supply and stored water can be vulnerable to contamination by microorganisms with deleterious health effects. The Metropolitan Zone of Guadalajara is a rapidly growing urban center with over five million residents where household storage is nearly ubiquitous. This pilot study was conducted in July 2018 to examine the microbiological quality of drinking water in Guadalajara. Samples were tested for free available chlorine residual, total coliform bacteria, and Escherichia coli. A survey on access to water and public perspectives was also conducted. Water exiting rooftop tanks exceeded regulatory limits for total coliform levels in half of the homes studied. Piped water arriving at two homes had total coliform levels that far exceeded regulatory limits. No E. coli were detected in any of the samples. Only 35% of homes had a chlorine residual between the recommended 0.2 and 1.5 mg/L. Many homes reported unpleasant odors and colors. Only 7% of residents drank the piped water. Future studies are needed, especially during April and May when many homes reported a higher disruption to water service.

Unintended pregnancy and subsequent postpartum long-acting reversible contraceptive use in Zimbabwe



The postpartum period is an opportune time for contraception adoption, as women have extended interaction with the reproductive healthcare system and therefore more opportunity to learn about and adopt contraceptive methods. This may be especially true for women who experience unintended pregnancy, a key target population for contraceptive programs and programs to eliminate mother-to-child HIV transmission. Among women in Zimbabwe surveyed in 2014, we examined the relationship between pregnancy intention associated with a woman’s most recent pregnancy, and her subsequent postpartum contraceptive use.


In our analysis we utilized a dataset from a random selection of catchment areas in Zimbabwe to examine the association between pregnancy intention of most recent pregnancy and subsequent postpartum contraceptive use using multinomial logistic regression models. We also explored whether this association differed by women’s HIV status. Finally, we examined the association between pregnancy intention and changes in contraception from the pre- to postpartum periods.


Findings suggest that women who reported that their pregnancy was unintended adopted less modern (all non-traditional) contraceptive methods overall, but adopted long-acting reversible contraception (LARC) more frequently than women reporting an intended pregnancy (OR 1.41; CI 1.18, 1.68). Among HIV-positive women, this relationship was particularly strong (OR 3.12; CI 1.96, 4.97). However, when examining changes in contraceptive use from the pre-pregnancy to the postpartum period, women who had an unintended pregnancy had lower odds of changing to a more effective method postpartum overall (OR 0.71; CI 0.64, 0.79).


We did not find evidence of higher modern method adoption in the postpartum period among women with an unintended pregnancy. However, women who were already on a method in the pre-pregnancy period were catalyzed to move to more effective methods (such as LARC) postpartum. This study provides evidence of low modern (non-traditional) method adoption in general in the postpartum period among a vulnerable sub-population in Zimbabwe (women who experience unintended pregnancy). Simultaneously, however, it shows a relatively greater portion specifically of LARC use among women with an unintended pregnancy. Further research is needed to more closely examine the motivations behind these contraceptive decisions in order to better inform distribution and counseling programs.

The impact of integrating medical assistants and community health workers on diabetes care management in community health centers



To compare the impact of implementing team-based diabetes care management involving community health workers (CHWs) vs. medical assistants (MA) in community health centers (CHCs) on diabetes care processes, intermediate outcomes, and patients’ experiences of chronic care.

Data sources

Clinical and administrative data (n = 6111) and patient surveys (n = 698) pre-intervention and post-intervention. Surveys (n = 285) and key informant interviews (n = 48) of CHC staff assessed barriers and facilitators of implementation.

Study design

A three-arm cluster-randomized trial of CHC sites integrating MAs (n = 3) or CHWs (n = 3) for diabetes care management compared control CHC sites (n = 10). Difference-in-difference multivariate regression with exact matching of patients estimated intervention effects.

Principal findings

Patients in the CHW intervention arm had improved annual glycated hemoglobin testing (18.5%, p < 0.001), while patients in the MA intervention arm had improved low-density lipoprotein cholesterol control (8.4%, p < 0.05) and reported better chronic care experiences over time (β=7.5, p < 0.001). Except for chronic care experiences (p < 0.05) for patients in the MA intervention group, difference-in-difference estimates were not statistically significant because control group patients also improved over time. Some diabetes care processes improved significantly more for control group patients than intervention group patients. Key informant interviews revealed that immediate patient care issues sometimes crowded out diabetes care management activities, especially for MAs.


Diabetes care improved in CHCs integrating CHWs and MAs onto primary care teams, but the improvements were no different than improvements observed among matched control group patients. Greater improvement using CHW and MA team-based approaches may be possible if practice leaders minimize use of these personnel to cover shortages that often arise in busy primary care practices.