Inactive hydrothermal vent microbial communities are important contributors to deep ocean primary productivity.

Active hydrothermal vents are oases for productivity in the deep ocean, but the flow of dissolved substrates that fuel such abundant life ultimately ceases, leaving behind inactive mineral deposits. The rates of microbial activity on these deposits are largely unconstrained. Here we show primary production occurs on inactive hydrothermal deposits and quantify its contribution to new organic carbon production in the deep ocean. Measured incorporation of 14C-bicarbonate shows that microbial communities on inactive deposits fix inorganic carbon at rates comparable to those on actively venting deposits. Single-cell uptake experiments and nanoscale secondary ion mass spectrometry showed chemoautotrophs comprise a large fraction (>30%) of the active microbial cells. Metagenomic and lipidomic surveys of inactive deposits further revealed that the microbial communities are dominated by Alphaproteobacteria and Gammaproteobacteria using the Calvin-Benson-Bassham pathway for carbon fixation. These findings establish inactive vent deposits as important sites for microbial activity and organic carbon production on the seafloor.

A female woolly mammoth's lifetime movements end in an ancient Alaskan hunter-gatherer camp.

Woolly mammoths in mainland Alaska overlapped with the region's first people for at least a millennium. However, it is unclear how mammoths used the space shared with people. Here, we use detailed isotopic analyses of a female mammoth tusk found in a 14,000-year-old archaeological site to show that she moved ~1000 kilometers from northwestern Canada to inhabit an area with the highest density of early archaeological sites in interior Alaska until her death. DNA from the tusk and other local contemporaneous archaeological mammoth remains revealed that multiple mammoth herds congregated in this region. Early Alaskans seem to have structured their settlements partly based on mammoth prevalence and made use of mammoths for raw materials and likely food.

Comparison of patient exit interviews with unannounced standardised patients for assessing HIV service delivery in Zambia: a study nested within a cluster randomised trial.

OBJECTIVES: To compare unannounced standardised patient approach (eg, mystery clients) with typical exit interviews for assessing patient experiences in HIV care (eg, unfriendly providers, long waiting times). We hypothesise standardised patients would report more negative experiences than typical exit interviews affected by social desirability bias. SETTING: Cross-sectional surveys in 16 government-operated HIV primary care clinics in Lusaka, Zambia providing antiretroviral therapy (ART). PARTICIPANTS: 3526 participants aged ≥18 years receiving ART participated in the exit surveys between August 2019 and November 2021. INTERVENTION: Systematic sample (every nth file) of patients in clinic waiting area willing to be trained received pre-visit training and post-visit interviews. Providers were unaware of trained patients. OUTCOME MEASURES: We compared patient experience among patients who received brief training prior to their care visit (explaining each patient experience construct in the exit survey, being anonymous, without manipulating behaviour) with those who did not undergo training on the survey prior to their visit. RESULTS: Among 3526 participants who participated in exit surveys, 2415 were untrained (56% female, median age 40 (IQR: 32-47)) and 1111 were trained (50% female, median age 37 (IQR: 31-45)). Compared with untrained, trained patients were more likely to report a negative care experience overall (adjusted prevalence ratio (aPR) for aggregate sum score: 1.64 (95% CI: 1.39 to 1.94)), with a greater proportion reporting feeling unwelcome by providers (aPR: 1.71 (95% CI: 1.20 to 2.44)) and witnessing providers behaving rude (aPR: 2.28 (95% CI: 1.63 to 3.19)). CONCLUSION: Trained patients were more likely to identify suboptimal care. They may have understood the items solicited better or felt empowered to be more critical. We trained existing patients, unlike studies that use 'standardised patients' drawn from outside the patient population. This low-cost strategy could improve patient-centred service delivery elsewhere. TRIAL REGISTRATION NUMBER: Assessment was nested within a parent study; www.pactr.org registered the parent study (PACTR202101847907585).

Patterns of person-centred communications in public HIV clinics: a latent class analysis using the Roter interaction analysis system.

INTRODUCTION: Poor client-provider communication is a critical barrier to long-term retention in care among people living with HIV. However, standardized assessments of this key metric are limited in Africa. We used the Roter Interaction Analysis System (RIAS) to quantitatively characterize patterns of person-centred communication (PCC) behaviours in Zambia. METHODS: We enrolled pairs of people living with HIV making routine HIV follow-up visit and their providers at 24 Ministry of Health-facilities supported by the Centre for Infectious Disease Research in Zambia in Lusaka province between August 2019 and November 2021. Client-provider encounters were audio-recorded and coded using RIAS by trained research staff. We performed latent class analysis to identify interactions with distinctive patterns of provider PCC behaviours (i.e. rapport building, person-centred counselling, PCC micropractices [e.g. brief empathy statements], assessing barriers to care, shared decision-making and leveraging discretionary power) and compared their distribution across client, provider, interaction and facility characteristics. RESULTS: We enrolled 478 people living with HIV and 139 providers (14% nurses, 73.6% clinical officers, 12.3% were medical officers). We identified four distinct profiles: (1) "Medically Oriented Interaction, Minimal PCC Behaviours" (47.6% of interactions) was characterized by medical discussion, minimal psychosocial/non-medical talk and low use of PCC behaviours; (2) "Balanced Medical/Non-medical Interaction, Low PCC Behaviours" (21.0%) was characterized by medical and non-medical discussion but limited use of other PCC behaviours; (3) "Medically Oriented Interaction, Good PCC Behaviours" (23.9%) was characterized by medically oriented discussion, more information-giving and increased use of PCC behaviours; and (4) "Highly person-centred Interaction" (7.5%) was characterized by both balanced medical/non-medical focus and the highest use of PCC behaviours. Nurse interactions were more likely to be characterized by more PCC behaviours (i.e. Class 3 or 4) (44.8%), followed by medical officers (33.9%) and clinical officers (27.3%) (p = 0.031). Longer interactions were also more likely to integrate more PCC behaviours (p < 0.001). CONCLUSIONS: PCC behaviours are relatively uncommon in HIV care in Zambia, and often limited to brief rapport-building statements and PCC micropractices. Strengthening PCC, such as shared decision-making and leveraging discretionary power to better accommodate client needs and preferences, may be an important strategy for improving the quality in HIV treatment programmes.

Provider perspectives on patient-centredness: participatory formative research and rapid analysis methods to inform the design and implementation of a facility-based HIV care improvement intervention in Zambia.

INTRODUCTION: Implementation of patient-centred care (PCC) practices in HIV treatment depends on healthcare workers' (HCWs) perceptions of the acceptability, appropriateness and feasibility of such practices (e.g. use of intentional, metric-driven activities to improve patient experiences). METHODS: We applied rapid, rigorous formative research methods to refine a PCC intervention for future trial. In 2018, we conducted focus group discussions (FGDs) with 46 HCWs purposefully selected from two pilot sites. We elicited HCW perceptions of HIV service delivery, HCW motivation and perceived value of patient experience measures intended to improve PCC. FGDs utilized participatory methods to understand HCW responses to patient-reported care engagement challenges and Scholl's PCC Framework principles (e.g. seeing a patient as a unique person), enablers (e.g. care coordination) and activities (e.g. patient involvement). Our rapid analysis used analytic memos, thematic analysis, research team debriefs and HCW feedback to inform time-sensitive trial implementation. RESULTS: While HCWs nearly universally identified with and supported principles of PCC in both facilities, they raised practical barriers given the practice environment. HCWs described motivation to help patients, attached value to seeing positive health outcomes and the importance of teamwork. However, HCWs reported challenges with enablers needed to deliver PCC. HCWs cited a work culture characterized by differential power dynamics between cadres and departments restricting HCW autonomy and resource access. Barriers included inflexibility in accommodating individual patient needs due to high patient volumes, limited human resources, laboratory capacity, infrastructure and skills translating patient perspectives into practice. HCW motivation was negatively influenced by encounters with "difficult patients," and feeling "unappreciated" by management, resulting in cognitive dissonance between HCW beliefs and behaviours. However, the enactment of PCC values also occurred. Results suggested that PCC interventions should reduce practice barriers, highlighting the value of mentors who could help HCWs dynamically engage with health system constraints, to facilitate PCC. CONCLUSIONS: While HCWs perceived PCC principles as acceptable, they did not think it universally appropriate or feasible given the practice environment. Participatory and rapid methods provided timely insight that PCC interventions must provide clear and effective systems enabling PCC activities by measuring and mitigating relational and organizational constraints amenable to change such as inter-cadre coordination.

Freshwater and anadromous fishing in Ice Age Beringia.

While freshwater and anadromous fish have been critical economic resources for late prehistoric and modern Native Americans, the origin and development of fishing is not well understood. We document the earliest known human use of freshwater and anadromous fish in North America by 13,000 and 11,800 years ago, respectively, from primary anthropogenic contexts in central Alaska (eastern Beringia). Fish use appears conditioned by broad climatic factors, as all occurrences but one are within the Younger Dryas chronozone. Earlier Bølling-Allerød and later early Holocene components, while exhibiting similar organic preservation, did not yield evidence of fishing, suggesting that this was a response to changing environmental factors, perhaps reductions in higher ranked resources such as large terrestrial mammals. Late Pleistocene and recent Indigenous peoples harvested similar fish taxa in the region (salmon, burbot, whitefish, and pike). We characterize late Pleistocene fishing in interior Beringia as an important element of broad-spectrum foraging rather than the intensive communal fishing and storage common among recent peoples.

Trajectories of re-engagement: factors and mechanisms enabling patient return to HIV care in Zambia.

INTRODUCTION: While disengagement from HIV care threatens the health of persons living with HIV (PLWH) and incidence-reduction targets, re-engagement is a critical step towards positive outcomes. Studies that establish a deeper understanding of successful return to clinical care among previously disengaged PLWH and the factors supporting re-engagement are essential to facilitate long-term care continuity. METHODS: We conducted narrative, patient-centred, in-depth interviews between January and June 2019 with 20 PLWH in Lusaka, Zambia, who had disengaged and then re-engaged in HIV care, identified through electronic medical records (EMRs). We applied narrative analysis techniques, and deductive and inductive thematic analysis to identify engagement patterns and enablers of return. RESULTS: We inductively identified five trajectories of care engagement, suggesting patterns in patient characteristics, experienced barriers and return facilitators that may aid intervention targeting including: (1) intermittent engagement;(2) mostly engaged; (3) delayed linkage after testing; (4) needs time to initiate antiretroviral therapy (ART); and (5) re-engagement with ART initiation. Patient-identified periods of disengagement from care did not always align with care gaps indicated in the EMR. Key, interactive re-engagement facilitators experienced by participants, with varied importance across trajectories, included a desire for physical wellness and social support manifested through verbal encouragement, facility outreach or personal facility connections and family instrumental support. The mechanisms through which facilitators led to return were: (1) the promising of living out one's life priorities; (2) feeling valued; (3) fostering interpersonal accountability; (4) re-entry navigation support; (5) facilitated care and treatment access; and (6) management of significant barriers, such as depression. CONCLUSIONS: While preliminary, the identified trajectories may guide interventions to support re-engagement, such as offering flexible ART access to patients with intermittent engagement patterns instead of stable patients only. Further, for re-engagement interventions to achieve impact, they must activate mechanisms underlying re-engagement behaviours. For example, facility outreach that reminds a patient to return to care but does not affirm a patient's value or navigate re-entry is unlikely to be effective. The demonstrated importance of positive health facility connections reinforces a growing call for patient-centred care. Additionally, interventions should consider the important role communities play in fostering treatment motivation and overcoming practical barriers.

Primates chunk simultaneously-presented memoranda.

Though much research has characterized both the behavior and electrophysiology of spatial memory for single targets in non-human primates, we know much less about how multiple memoranda are handled. Multiple memoranda may interact in the brain, affecting the underlying representations. Mnemonic resources are famously limited, so items may compete for "space" in memory or may be encoded cooperatively or in a combined fashion. Understanding the mode of interaction will inform future neural studies. As a first step, we quantified interactions during a multi-item spatial memory task. Two monkeys were shown 1-4 target locations. After a delay, the targets reappeared with a novel target and the animal was rewarded for fixating the novel target. Targets could appear either all at once (simultaneous) or with intervening delays (sequential). We quantified the degree of interaction with memory rate correlations. We found that simultaneously presented targets were stored cooperatively while sequentially presented targets were stored independently. These findings demonstrate how interaction between concurrently memorized items depends on task context. Future studies of multi-item memory would be served by designing experiments to either control or measure the mode of this interaction.

HIV care experiences and health priorities during the first wave of COVID-19: clients' perspectives - a qualitative study in Lusaka, Zambia.

BACKGROUND: The novel COVID-19 pandemic threatened to disrupt access to human immunodeficiency (HIV) treatment for persons living with HIV (PLHIV), two-thirds of whom live in sub-Saharan Africa. To inform a health system response supportive of continuity of care, we sought to understand clients' HIV care experiences and health priorities during the first wave of COVID-19 outbreak in Lusaka, Zambia. METHODS: Leveraging a study cohort of those who completed periodic SMS surveys on HIV care, we purposefully sampled 25 PLHIV after first confirmed COVID-19 case was reported in Zambia on 18th March 2020. We phone-interviewed participants, iteratively refining interview guide to capture emergent themes on COVID-19 awareness, health facility interactions, and social circumstances, which we analyzed using matrix analysis. RESULTS: All participants were aware of COVID-19, and HIV care experiences and health priorities of clients were affected by associated changes at health system, household, and individual level. The health system instituted early clinic visits to provide 6-months of antiretroviral therapy (ART) for stable patients and 3-months for unstable patients to reduce clinic visits and wait times. Most patients welcomed this long-desired extended appointment spacing. Some reported feeling respected and engaged when health care workers telephoned requesting their early clinic visit. However, others felt discouraged by an absence of physical distancing during their clinic visit due to 'severe acute respiratory syndrome coronavirus 2' (SARS-CoV-2) infection concerns. Several expressed a lack of clarity regarding next viral load monitoring date and means for receiving results. Patients suggested regular patient-facility communication by telephone and SMS. Patients emphasized that COVID-19 restrictions led to loss of employment and household income, exacerbating poverty and difficulties in taking ART. At individual level, most participants felt motivated to stay healthy during COVID-19 by ART adherence and regular laboratory monitoring. CONCLUSIONS: Clients' HIV care and health priorities during the first wave of COVID-19 in Lusaka province were varied with a combination of positive and negative experiences that occurred especially at health system and individual levels, while at household level, the experiences were all negative. More research is needed to understand how patients practice resiliency in the widespread context of socio-economic instability. Governments and patients must work together to find local, health systems solutions to support ART adherence and monitoring. Additionally, the health system should consider how to build on changes for long-term HIV management and service delivery.

Late date of human arrival to North America: Continental scale differences in stratigraphic integrity of pre-13,000 BP archaeological sites.

By 13,000 BP human populations were present across North America, but the exact date of arrival to the continent, especially areas south of the continental ice sheets, remains unclear. Here we examine patterns in the stratigraphic integrity of early North American sites to gain insight into the timing of first colonization. We begin by modeling stratigraphic mixing of multicomponent archaeological sites to identify signatures of stratigraphic integrity in vertical artifact distributions. From those simulations, we develop a statistic we call the Apparent Stratigraphic Integrity Index (ASI), which we apply to pre- and post-13,000 BP archaeological sites north and south of the continental ice sheets. We find that multiple early Beringian sites dating between 13,000 and 14,200 BP show excellent stratigraphic integrity. Clear signs of discrete and minimally disturbed archaeological components do not appear south of the ice sheets until the Clovis period. These results provide support for a relatively late date of human arrival to the Americas.

'I need time to start antiretroviral therapy': understanding reasons for delayed ART initiation among people diagnosed with HIV in Lusaka, Zambia'.

INTRODUCTION: Rapid antiretroviral therapy (ART) initiation can improve patient outcomes such as viral suppression and prevent new infections. However, not everyone who can start ART does so immediately. METHODS: We conducted a qualitative study to inform interventions supporting rapid initiation in the 'Test and Start' era. We purposively sampled 20 adult patients living with HIV and a previous gap in care from ten health facilities in Lusaka, Zambia for interviews. We inductively analysed transcripts using a thematic, narrative approach. In their narratives, seven participants discussed delaying ART initiation. RESULTS: Drawing on messages gleaned from facility-based counselling and community information, many cited greater fear of rapid sickness or death due to imperfect adherence or treatment side effects than negative health consequences due to delayed initiation. Participants described needing time to 'prepare' their minds for a lifetime treatment commitment. Concerns about inadvertent HIV status disclosure during drug collection discouraged immediate initiation, as did feeling healthy, and worries about the impact of ART initiation on relationship dynamics. CONCLUSION: Findings suggest that counselling messages should accurately communicate treatment risks, without perpetuating fear-based narratives about HIV. Identifying and managing patient-specific concerns and reasons for the 'need for time' may be important for supporting individuals to rapidly accept lifelong treatment.Key messagesFear-based adherence messaging in health facilities about the dangers of missing a treatment dose or changing the time when ART is taken contributes to Zambian patients' refusals of immediate ART initiationResponsive health systems that balance a stated need for time to accept one's diagnosis and prepare to embark on a lifelong treatment plan with interventions to identify and manage patient-specific treatment related fears and concerns may support more rapid ART initiationPerceived social stigma around HIV continues to be a significant challenge for treatment initiation.

"Provider discretionary power practices to support implementation of patient-centered HIV care in Lusaka, Zambia".

Introduction: Traditional patient-provider relationships privilege the providers, as they possess the formal authority and clinical knowledge applied to address illness, but providers also have discretion over how they exercise their power to influence patients' services, benefits, and sanctions. In this study, we assessed providers' exercise of discretionary power in implementing patient-centered care (PCC) practices in Lusaka, Zambia. Methods: HIV clinical encounters between patients on antiretroviral therapy (ART) and providers across 24 public health facilities in Lusaka Province were audio recorded and transcribed verbatim. Using qualitative content analysis, we identified practices of discretionary power (DP) employed in the implementation of PCC and instances of withholding DP. A codebook of DP practices was inductively and iteratively developed. We compared outcomes across provider cadres and within sites over time. Results: We captured 194 patient-provider interactions at 24 study sites involving 11 Medical Officers, 58 Clinical Officers and 10 Nurses between August 2019 to May 2021. Median interaction length was 7.5 min. In a hierarchy where providers dominate patients and interactions are rapid, some providers invited patients to ask questions and responded at length with information that could increase patient understanding and agency. Others used inclusive language, welcomed patients, conducted introductions, and apologized for delayed services, narrowing the hierarchical distance between patient and provider, and facilitating recognition of the patient as a partner in care. Although less common, providers shared their decision-making powers, allowing patients to choose appointment dates and influence regimens. They also facilitated resource access, including access to services and providers outside of scheduled appointment times. Application of DP was not universal and missed opportunities were identified. Conclusion: Supporting providers to recognize their power and intentionally share it is both inherent to the practice of PCC (e.g., making a patient a partner), and a way to implement improved patient support. More research is needed to understand the application of DP practices in improving the patient-centeredness of care in non-ART settings.

A controlled study to assess the effects of a Fast Track (FT) service delivery model among stable HIV patients in Lusaka Zambia.

Fast Track models-in which patients coming to facility to pick up medications minimize waiting times through foregoing clinical review and collecting pre-packaged medications-present a potential strategy to reduce the burden of treatment. We examine effects of a Fast Track model (FT) in a real-world clinical HIV treatment program on retention to care comparing two clinics initiating FT care to five similar (in size and health care level), standard of care clinics in Zambia. Within each clinic, we selected a systematic sample of patients meeting FT eligibility to follow prospectively for retention using both electronic medical records as well as targeted chart review. We used a variety of methods including Kaplan Meier (KM) stratified by FT, to compare time to first late pick up, exploring late thresholds at >7, >14 and >28 days, Cox proportional hazards to describe associations between FT and late pick up, and linear mixed effects regression to assess the association of FT with medication possession ratio. A total of 905 participants were enrolled with a median age of 40 years (interquartile range [IQR]: 34-46 years), 67.1% were female, median CD4 count was 499 cells/mm3 (IQR: 354-691), and median time on ART was 5 years (IQR: 3-7). During the one-year follow-up period FT participants had a significantly reduced cumulative incidence of being >7 days late for ART pick-up (0.36, 95% confidence interval [CI]: 0.31-0.41) compared to control participants (0.66; 95% CI: 0.57-0.65). This trend held for >28 days late for ART pick-up appointments, at 23% (95% CI: 18%-28%) among intervention participants and 54% (95% CI: 47%-61%) among control participants. FT models significantly improved timely ART pick up among study participants. The apparent synergistic relationship between refill time and other elements of the FT suggest that FT may enhance the effects of extending visit spacing/multi-month scripting alone. ClinicalTrials.gov Identifier: NCT02776254 https://clinicaltrials.gov/ct2/show/NCT02776254.

The effect of tracer contact on return to care among adult, "lost to follow-up" patients living with HIV in Zambia: an instrumental variable analysis.

INTRODUCTION: Tracing patients lost to follow-up (LTFU) from HIV care is widely practiced, yet we have little knowledge of its causal effect on care engagement. In a prospective, Zambian cohort, we examined the effect of tracing on return to care within 2 years of LTFU. METHODS: We traced a stratified, random sample of LTFU patients who had received HIV care between August 2013 and July 2015. LTFU was defined as a gap of >90 days from last scheduled appointment in the routine electronic medical record. Extracting 2 years of follow-up visit data through 2017, we identified patients who returned. Using random selection for tracing as an instrumental variable (IV), we used conditional two-stage least squares regression to estimate the local average treatment effect of tracer contact on return. We examined the observational association between tracer contact and return among patient sub-groups self-confirmed as disengaged from care. RESULTS: Of the 24,164 LTFU patients enumerated, 4380 were randomly selected for tracing and 1158 were contacted by a tracer within a median of 14.8 months post-loss. IV analysis found that patients contacted by a tracer because they were randomized to tracing were no more likely to return than those not contacted (adjusted risk difference [aRD]: 3%, 95% CI: -2%, 8%, p = 0.23). Observational data showed that among contacted, disengaged patients, the rate of return was higher in the week following tracer contact (IR 5.74, 95% CI: 3.78-8.71) than in the 2 weeks to 1-month post-contact (IR 2.28, 95% CI: 1.40-3.72). There was a greater effect of tracing among patients lost for >6 months compared to those contacted within 3 months of loss. CONCLUSIONS: Overall, tracer contact did not causally increase LTFU patient return to HIV care, demonstrating the limited impact of tracing in this program, where contact occurred months after patients were LTFU. However, observational data suggest that tracing may speed return among some LTFU patients genuinely out-of-care. Further studies may improve tracing effectiveness by examining the mechanisms underlying the impact of tracing on return to care, the effect of tracing at different times-since-loss and using more accurate identification of patients who are truly disengaged to target tracing.

Effects of implementing universal and rapid HIV treatment on initiation of antiretroviral therapy and retention in care in Zambia: a natural experiment using regression discontinuity.

BACKGROUND: Universal testing and treatment (UTT) for all people living with HIV has only been assessed under experimental conditions in cluster-randomised trials. The public health effectiveness of UTT policies on the HIV care cascade under real-world conditions is not known. We assessed the real-world effectiveness of universal HIV treatment policies that were implemented in Zambia on Jan 1, 2017. METHODS: We used data from Zambia's routine electronic health record system to analyse antiretroviral therapy (ART)-naive adults who newly enrolled in HIV care up to 1 year before and after the implementation of universal treatment (ie, Jan 1, 2016, to Jan 1, 2018) at 117 clinics supported by the Centre for Infectious Disease Research in Zambia. We used a regression discontinuity design to estimate the effects of implementing UTT on same-day ART initiation, ART initiation within 1 month, and retention on ART at 12 months (defined as clinic attendance 9-15 months after enrolment and at least 6 months on ART), under the assumption that patients presenting immediately before and after UTT implementation were balanced on both measured and unmeasured characteristics. We did an instrumental variable analysis to estimate the effect of same-day ART initiation under routine conditions on 12-month retention on ART. FINDINGS: 65 673 newly enrolled patients with HIV (40 858 [62·2%] female, median age 32 years [IQR 26-39], median CD4 count 287 cells per µL [IQR 147-466]) were eligible for inclusion in the analyses; 31 145 enrolled before implementation of UTT, and 34 528 enrolled after UTT. Implementation of universal treatment increased same-day ART initiation from 41·7% to 74·8% (risk difference [RD] 33·1%, 95% CI 30·5-35·7), ART initiation by 1 month from 69·6% to 87·0% (RD 17·4%, 15·5-19·3), and 12-month retention on ART from 56·2% to 63·3% (RD 7·1%, 4·3-9·9). ART initiation rates became more uniform across patient subgroups after implementation of universal treatment, but heterogeneity in 12-month retention on ART between subgroups was unchanged. Instrumental variable analyses indicated that same-day ART initiation in routine settings led to a 15·8% increase (95% CI 12·1-19·5) in 12-month retention on ART. INTERPRETATION: UTT policies implemented in Zambia increased the rapidity and uptake of ART, as well as retention on ART at 12 months, although overall retention on ART remained suboptimal. UTT policies reduced disparities in treatment initiation, but not 12-month retention on ART. Natural experiments reveal both the anticipated and unanticipated effects of real-world implementation and indicate the need for new strategies leveraging the short-term effects of UTT to cultivate long-term treatment success. FUNDING: National Institutes of Health.

Bacteria-Oil Microaggregates Are an Important Mechanism for Hydrocarbon Degradation in the Marine Water Column.

Following oil spills in aquatic environments, oil-associated flocculants observed within contaminated waters ultimately lead to the sedimentation of oil as marine oil snow (MOS). To better understand the role of aggregates in hydrocarbon degradation and transport, we experimentally produced a MOS sedimentation event using Gulf of Mexico coastal waters amended with oil or oil plus dispersant. In addition to the formation of MOS, smaller micrometer-scale (10- to 150-µm) microbial aggregates were observed. Visual inspection of these microaggregates revealed that they were most abundant in the oil-amended treatments and frequently associated with oil droplets, linking their formation to the presence of oil. The peak abundance of the microaggregates coincided with the maximum rates of biological hydrocarbon oxidation estimated by the mineralization of 14C-labeled hexadecane and naphthalene. To elucidate the potential of microaggregates to serve as hot spots for hydrocarbon degradation, we characterized the free-living and aggregate-associated microbial assemblages using 16S rRNA gene sequencing. The microaggregate population was found to be bacterially dominated and enriched with putative hydrocarbon-degrading taxa. Direct observation of some of these taxa using catalyzed reporter deposition fluorescence in situ hybridization confirmed their greater abundance within microaggregates relative to the surrounding seawater. Metagenomic sequencing of these bacteria-oil microaggregates (BOMAs) further supported their community's capacity to utilize a wide variety of hydrocarbon compounds. Taken together, these data highlight that BOMAs are inherent features in the biological response to oil spills and likely important hot spots for hydrocarbon oxidation in the ocean. IMPORTANCE Vast quantities of oil-associated marine snow (MOS) formed in the water column as part of the natural biological response to the Deepwater Horizon drilling accident. Despite the scale of the event, uncertainty remains about the mechanisms controlling MOS formation and its impact on the environment. In addition to MOS, we observed micrometer-scale (10- to 150-µm) aggregates whose abundance coincided with maximum rates of hydrocarbon degradation and whose composition was dominated by hydrocarbon-degrading bacteria with the genetic potential to metabolize a range of these compounds. This targeted study examining the role of these bacteria-oil microaggregates in hydrocarbon degradation reveals details of this fundamental component of the biological response to oil spills, and with it, alterations to biogeochemical cycling in the ocean.

Local field potentials in the parietal reach region reveal mechanisms of bimanual coordination.

Primates use their arms in complex ways that frequently require coordination between the two arms. Yet the planning of bimanual movements has not been well-studied. We recorded spikes and local field potentials (LFP) from the parietal reach region (PRR) in both hemispheres simultaneously while monkeys planned and executed unimanual and bimanual reaches. From analyses of interhemispheric LFP-LFP and spike-LFP coherence, we found that task-specific information is shared across hemispheres in a frequency-specific manner. This shared information could arise from common input or from direct communication. The population average unit activity in PRR, representing PRR output, encodes only planned contralateral arm movements while beta-band LFP power, a putative PRR input, reflects the pattern of planned bimanual movement. A parsimonious interpretation of these data is that PRR integrates information about the movement of the left and right limbs, perhaps in service of bimanual coordination.

Genomics of Environmental Salmonella: Engaging Students in the Microbiology and Bioinformatics of Foodborne Pathogens.

We have developed and implemented an undergraduate microbiology course in which students isolate, characterize, and perform whole genome assembly and analysis of Salmonella enterica from stream sediments and poultry litter. In the development of the course and over three semesters, successive teams of undergraduate students collected field samples and performed enrichment and isolation techniques specific for the detection of S. enterica. Eighty-eight strains were confirmed using standard microbiological methods and PCR of the invA gene. The isolates' genomes were Illumina-sequenced by the Center for Food Safety and Applied Nutrition at the FDA and the Virginia state Division of Consolidated Laboratory Services as part of the GenomeTrakr program. Students used GalaxyTrakr and other web- and non-web-based platforms and tools to perform quality control on raw and assembled sequence data, assemble, and annotate genomes, identify antimicrobial resistance and virulence genes, putative plasmids, and other mobile genetic elements. Strains with putative plasmid-borne antimicrobial resistance genes were further sequenced by students in our research lab using the Oxford Nanopore MinIONTM platform. Strains of Salmonella that were isolated include human infectious serotypes such as Typhimurium and Infantis. Over 31 of the isolates possessed antibiotic resistance genes, some of which were located on large, multidrug resistance plasmids. Plasmid pHJ-38, identified in a Typhimurium isolate, is an apparently self-transmissible 183 kb IncA/C2 plasmid that possesses multiple antimicrobial resistance and heavy-metal resistance genes. Plasmid pFHS-02, identified in an Infantis isolate, is an apparently self-transmissible 303 kb IncF1B plasmid that also possesses numerous heavy-metal and antimicrobial resistance genes. Using direct and indirect measures to assess student outcomes, results indicate that course participation contributed to cognitive gains in relevant content knowledge and research skills such as field sampling, molecular techniques, and computational analysis. Furthermore, participants self-reported a deeper interest in scientific research and careers as well as psychosocial outcomes (e.g., sense of belonging and self-efficacy) commonly associated with student success and persistence in STEM. Overall, this course provided a powerful combination of field, wet lab, and computational biology experiences for students, while also providing data potentially useful in pathogen surveillance, epidemiological tracking, and for the further study of environmental reservoirs of S. enterica.

The revolving door of HIV care: Revising the service delivery cascade to achieve the UNAIDS 95-95-95 goals.

Peter Ehrenkranz and co-authors present a cyclical cascade of care for people with HIV infection, aiming to facilitate assessment of outcomes.

Primate Spatial Memory Cells Become Tuned Early and Lose Tuning at Cell-Specific Times.

Working memory, the ability to maintain and transform information, is critical for cognition. Spatial working memory is particularly well studied. The premier model for spatial memory is the continuous attractor network, which posits that cells maintain constant activity over memory periods. Alternative models propose complex dynamics that result in a variety of cell activity time courses. We recorded from neurons in the frontal eye fields and dorsolateral prefrontal cortex of 2 macaques during long (5-15 s) memory periods. We found that memory cells turn on early after stimulus presentation, sustain activity for distinct and fixed lengths of time, then turn off and stay off for the remainder of the memory period. These dynamics are more complex than the dynamics of a canonical bump attractor network model (either decaying or nondecaying) but more constrained than the dynamics of fully heterogeneous memory models. We speculate that memory may be supported by multiple attractor networks working in parallel, with each network having its own characteristic mean turn-off time such that mnemonic resources are gradually freed up over time.