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1.
Int J Impot Res ; 35(3): 269-278, 2023 May.
Article in English | MEDLINE | ID: mdl-34702986

ABSTRACT

Ideally, the benefits of public health interventions should outweigh any associated harms, burdens, and adverse unintended consequences. The intended benefit of voluntary medical male circumcision (VMMC) programs in eastern and southern Africa (ESA) is the reduction of HIV infections. We review the literature for evidence of reductions in HIV incidence, evaluate the extent to which decreases in HIV incidence can be reasonably attributed to VMMC programs, and summarize social harms and ethical concerns associated with these programs. Review findings suggest that HIV incidence had been declining across ESA since before the large-scale rollout of VMMC as a public health intervention, and that this decline may be due to the combined effects of HIV prevention and treatment interventions, such as expanded antiretroviral therapy. The independent effect of VMMC programs in reducing HIV infections at the population level remains unknown. On the other hand, VMMC-associated evidence is increasing for the existence of negative social impacts such as stigmatization and/or discrimination, and ethically problematic practices, including lack of informed consent. We conclude that the relationship between the benefits and burdens of VMMC programs may be more unfavorable than what has been commonly suggested by proponents of global VMMC campaigns.


Subject(s)
Circumcision, Male , HIV Infections , Humans , Male , HIV Infections/epidemiology , HIV Infections/prevention & control , Public Health , Africa South of the Sahara/epidemiology , Voluntary Programs
2.
Int J Drug Policy ; 103: 103613, 2022 05.
Article in English | MEDLINE | ID: mdl-35255391

ABSTRACT

BACKGROUND: People who use illicit drugs (PWUD) remain at significantly elevated risk for HIV infection and continue to have very low testing rates. HIV self-testing (HIVST) has been shown to be acceptable among many high-risk populations, but less is known about PWUD. METHODS: From May-June 2021, a HIVST program was implemented at a syringe services program (SSP) in Louisville, Kentucky. PWUD were given the option to privately self-test at the SSP or take the test home and follow-up with study staff. Primary outcomes were acceptability, ease of use, usability, reasons for self-testing, testing location, frequency of future testing, and preference for future testing location. RESULTS: Among 230 study participants, 77% reported high acceptability (i.e., the HIVST kits made them feel much more able to keep track of their HIV status compared to standard testing methods). Virtually all (97.4%) reported the test kits were very easy to use. Problems while using the HIVST kits were rare (range 1.3-3.0%). The most common reasons for testing were a desire to know their status (85.2%), the test was free (37%), and the short duration for results (30.9%). Testing primarily occurred onsite (87.8%). The majority (83%) reported they would use the HIVST kits at least every six months if made available through the health department and would prefer to test at home (71.7%). Multivariate analyses found that awareness of and intention to use pre-exposure prophylaxis (PrEP) were significantly associated with high acceptability and testing onsite. CONCLUSION: Study participants found HIVST to be acceptable and very easy to use. The multivariate findings suggest HIVST interventions should be packaged with PrEP interventions and harm reduction programs.


Subject(s)
HIV Infections , Illicit Drugs , Pre-Exposure Prophylaxis , HIV Infections/diagnosis , HIV Infections/prevention & control , HIV Testing , Humans , Mass Screening , Self-Testing
3.
BMC Med Ethics ; 22(1): 169, 2021 12 28.
Article in English | MEDLINE | ID: mdl-34961509

ABSTRACT

HIV remission clinical researchers are increasingly seeking study participants who are diagnosed and treated during acute HIV infection-the brief period between infection and the point when the body creates detectable HIV antibodies. This earliest stage of infection is often marked by flu-like illness and may be an especially tumultuous period of confusion, guilt, anger, and uncertainty. Such experiences may present added ethical challenges for HIV research recruitment, participation, and retention. The purpose of this paper is to identify potential ethical challenges associated with involving acutely diagnosed people living with HIV in remission research and considerations for how to mitigate them. We identify three domains of potential ethical concern for clinicians, researchers, and ethics committee members to consider: 1) Recruitment and informed consent; (2) Transmission risks and partner protection; and (3) Ancillary and continuing care. We discuss each of these domains with the aim of inspiring further work to advance the ethical conduct of HIV remission research. For example, experiences of confusion and uncertainty regarding illness and diagnosis during acute HIV infection may complicate informed consent procedures in studies that seek to recruit directly after diagnosis. To address this, it may be appropriate to use staged re-consent procedures or comprehension assessment. Responsible conduct of research requires a broad understanding of acute HIV infection that encompasses its biomedical, psychological, social, and behavioral dimensions. We argue that the lived experience of acute HIV infection may introduce ethical concerns that researchers and reviewers should address during study design and ethical approval.


Subject(s)
HIV Infections , HIV Infections/diagnosis , Humans , Informed Consent , Morals , Research Design , Research Personnel
4.
Public Health Ethics ; 14(1): 79-89, 2021 Apr.
Article in English | MEDLINE | ID: mdl-34239604

ABSTRACT

Ongoing global efforts to circumcise adolescent and adult males to reduce their risk of acquiring HIV constitute the largest public health prevention initiative, using surgical means, in human history. Voluntary medical male circumcision (VMMC) programs in Africa have significantly altered social norms related to male circumcision among previously non-circumcising groups and groups that have practiced traditional (non-medical) circumcision. One consequence of this change is the stigmatization of males who, for whatever reason, remain uncircumcised. This paper discusses the ethics of stigma with regard to uncircumcised adolescent males in global VMMC programs, particularly in certain recruitment, demand creation and social norm interventions. Grounded in our own experiences gained while conducting HIV-related ethics research with adolescents in Kenya, we argue that use of explicit or implicit stigma to increase the number of VMMC volunteers is unethical from a public health ethics perspective, particularly in campaigns that leverage social norms of masculinity. Ongoing global efforts to circumcise adolescent and adult males to reduce their risk of acquiring HIV constitute the largest public health prevention initiative, using surgical means, in human history. VMMC programs in Africa have significantly altered social norms related to male circumcision among previously non-circumcising groups and groups that have practiced traditional (non-medical) circumcision. One consequence of this change is the stigmatization of males who, for whatever reason, remain uncircumcised. This paper discusses the ethics of stigma with regard to uncircumcised adolescent males in global VMMC programs, particularly in certain recruitment, demand creation and social norm interventions. Grounded in our own experiences gained while conducting HIV-related ethics research with adolescents in Kenya, we argue that use of explicit or implicit stigma to increase the number of VMMC volunteers is unethical from a public health ethics perspective, particularly in campaigns that leverage social norms of masculinity.

5.
Cult Health Sex ; 23(12): 1641-1655, 2021 12.
Article in English | MEDLINE | ID: mdl-32748729

ABSTRACT

Biomedical advances in diagnostics, treatment and prevention increase the means available to reduce HIV transmission risk. Subsequent shifts in HIV status disclosure obligation and ethics may impact how those living with HIV view, enact and experience disclosure. We analysed focus group and interview data to explore how these changes are reflected in disclosure decision-making to sexual partners among young gay and bisexual men living with HIV in the USA. Three interrelated themes were identified: engaging with partners' varying HIV knowledge; attribution of blame; and negotiating disclosure-related harms. Participants experienced blame from partners that questioned the timing of HIV testing, status disclosure and sex events without regards for viral suppression or use of pre-exposure prophylaxis. Substantial HIV stigma was described in response to disclosure, mitigated in some cases by partners' higher HIV knowledge. Overall, an uneven diffusion of HIV treatment and prevention knowledge and continuing HIV stigma seemed to limit the translation of biomedical advances into improved disclosure experiences. Our findings suggest that young gay and bisexual men living with HIV may continue to perform much of the moral labour involved in disclosure by managing others' reactions, correcting inaccurate sexual health information, and negotiating the risks of disclosure-related harm.


Subject(s)
HIV Infections , Sexual and Gender Minorities , Disclosure , HIV Infections/prevention & control , Homosexuality, Male , Humans , Male , Morals , Sexual Behavior , Sexual Partners
6.
J Med Ethics ; 2020 Nov 04.
Article in English | MEDLINE | ID: mdl-33148776

ABSTRACT

The use of targets to direct public health programmes, particularly in global initiatives, has become widely accepted and commonplace. This paper is an ethical analysis of the utilisation of targets in global public health using our fieldwork on and experiences with voluntary medical male circumcision (VMMC) initiatives in Kenya. Among the many countries involved in VMMC for HIV prevention, Kenya is considered a success story, its programmes having medically circumcised nearly 2 million men since 2007. We describe ethically problematic practices in Kenyan VMMC programmes revealed by our fieldwork, how the problems are related to the pursuit of targets and discuss possible approaches to their management. Although the establishment and pursuit of targets in public health can have many benefits, assessments of target-driven programmes tend to focus on quantifiable outcomes rather than the processes by which the outcomes are obtained. However, in order to speak more robustly about programmatic 'success', and to maintain community trust, it is vital to ethically evaluate how a public health initiative is actually implemented in the pursuit of its targets.

7.
PLoS One ; 14(11): e0224548, 2019.
Article in English | MEDLINE | ID: mdl-31682626

ABSTRACT

INTRODUCTION: Voluntary medical male circumcision (VMMC) provides significant reductions in the risk of female-to-male HIV transmission. Since 2007, VMMC has been a key component of the United States President's Emergency Plan for AIDS Relief's (PEPFAR) strategy to mitigate the HIV epidemic in countries with high HIV prevalence and low circumcision rates. To ensure intended effects, PEPFAR sets ambitious annual circumcision targets and provides funding to implementation partners to deliver local VMMC services. In Kenya to date, 1.9 million males have been circumcised; in 2017, 60% of circumcisions were among 10-14-year-olds. We conducted a qualitative field study to learn more about VMMC program implementation in Kenya. METHODS AND RESULTS: The study setting was a region in Kenya with high HIV prevalence and low male circumcision rates. From March 2017 through April 2018, we carried out in-depth interviews with 29 VMMC stakeholders, including "mobilizers", HIV counselors, clinical providers, schoolteachers, and policy professionals. Additionally, we undertook observation sessions at 14 VMMC clinics while services were provided and observed mobilization activities at 13 community venues including, two schools, four public marketplaces, two fishing villages, and five inland villages. Analysis of interview transcripts and observation field notes revealed multiple unintended consequences linked to the pursuit of targets. Ebbs and flows in the availability of school-age youths together with the drive to meet targets may result in increased burdens on clinics, long waits for care, potentially misleading mobilization practices, and deviations from the standard of care. CONCLUSION: Our findings indicate shortcomings in the quality of procedures in VMMC programs in a low-resource setting, and more importantly, that the pursuit of ambitious public health targets may lead to compromised service delivery and protocol adherence. There is a need to develop improved or alternative systems to balance the goal of increasing service uptake with the responsible conduct of VMMC.


Subject(s)
Circumcision, Male/statistics & numerical data , HIV Infections/prevention & control , Health Plan Implementation/statistics & numerical data , Quality of Health Care , Voluntary Programs/statistics & numerical data , Adolescent , Adult , Circumcision, Male/standards , Female , HIV Infections/epidemiology , Health Plan Implementation/organization & administration , Health Plan Implementation/standards , Humans , International Cooperation , Kenya/epidemiology , Male , Prevalence , Stakeholder Participation , Standard of Care , Time Factors , Voluntary Programs/organization & administration , Voluntary Programs/standards , Workload/statistics & numerical data
8.
AIDS Behav ; 23(12): 3460-3470, 2019 Dec.
Article in English | MEDLINE | ID: mdl-31375957

ABSTRACT

In priority sub-Saharan African countries, on the ground observations suggest that the success of voluntary medical male circumcision (VMMC) programs should not be based solely on numbers of males circumcised. We identify gaps in the consent process and poor psychosocial outcomes among a key target group: male adolescents. We assessed compliance with consent and assent requirements for VMMC in western Kenya among males aged 15-19 (N = 1939). We also examined differences in quality of life, depression, and anticipated HIV stigma between uncircumcised and circumcised adolescents. A substantial proportion reported receiving VMMC services as minors without parent/guardian consent. In addition, uncircumcised males were significantly more likely than their circumcised peers to have poor quality of life and symptoms of depression. Careful monitoring of male adolescents' well-being is needed in large-scale VMMC programs. There is also urgent need for research to identify effective strategies to address gaps in the delivery of VMMC services.


Subject(s)
Circumcision, Male/psychology , Depression/psychology , HIV Infections/prevention & control , Informed Consent By Minors/psychology , Parental Consent , Psychological Distress , Quality of Life/psychology , Social Stigma , Adolescent , Female , Humans , Informed Consent , Kenya , Male , Young Adult
9.
Ethics Hum Res ; 41(3): 13-22, 2019 May.
Article in English | MEDLINE | ID: mdl-31108576

ABSTRACT

The relationship between risks and benefits is central to the ethics of research involving human participants. Traditionally, to be ethically justifiable, risks should be reasonable in relation to anticipated benefits (if any) to subjects and to the potential social benefits resulting from research. This calculus is being further complicated by findings from an increasing number of social science studies that reveal that prospective and actual research participants frequently describe various types of inclusion benefits (for example, personal benefits such as access to or improved health care, increased knowledge about their disease or condition, and greater solidarity with the local community) as important to them. What is the ethical significance of such inclusion benefits, particularly those nonmedical in nature, for research ethics committees' risk-benefit assessment of research studies? We argue that, unless participants are clearly mistaken in their perceptions, ethics committees should take these types of inclusion benefits into account, and we suggest a few ways this might look in practice.


Subject(s)
Ethical Review , Ethics Committees, Research , Research Subjects , Adolescent , Adult , Biomedical Research/ethics , Ethical Review/standards , Humans , Kenya , Patient Selection/ethics , Research Subjects/psychology , Risk Assessment/standards , Social Sciences/ethics , Social Validity, Research/standards , Thailand
10.
AIDS Res Hum Retroviruses ; 35(1): 100-107, 2019 01.
Article in English | MEDLINE | ID: mdl-30009625

ABSTRACT

Currently, much of early phase HIV cure research involves unknown and potentially serious risks, with little or no chance of direct health benefits. During informed consent, researchers emphasize this lack of personal medical benefit to minimize misconceptions that undermine genuine consent. We explored participants' and researchers' perspectives on HIV cure clinical research participation and its potential benefits. We conducted semistructured interviews with 17 HIV cure research participants and nine researchers in North Carolina, USA. We analyzed interviews to identify participant experience-related themes. We were particularly interested in indirect benefits, such as psychological support or improved care. We also assessed five consent documents for benefit/risk-related language. Research participants were male, with a median age of 50 (range: 28-62); most were non-Hispanic white (15/17) and men who have sex with men (13/17). All 17 trial participants found research participation meaningful and beneficial. Reported benefits included improved healthcare (16/17), HIV knowledge (13/17), intimate relationships (10/17), and positive behaviors (6/17). In addition, all participants described psychological benefits, including increased positive outlook, improved sense of purpose, emotional support, and enriched self-image. Participants reported risks such as quality of life concerns, uncomfortable procedures (e.g., leukapheresis), latency reversal, and HIV status disclosure. While the consent documents included discussion of these and other risks, they did not mention potential indirect benefits. Individuals involved in HIV clinical research have recognized participant psychological, social, and behavioral benefits. We recommend that researchers and institutional review boards consider these benefits for inclusion during risk/benefit assessments, consent procedures, and other discussions with prospective participants.


Subject(s)
HIV Infections/psychology , HIV Infections/therapy , Patients/psychology , Research Personnel/psychology , Adolescent , Adult , Clinical Trials as Topic , Humans , Interviews as Topic , Male , Middle Aged , North Carolina , Quality of Life , Young Adult
11.
Nat Commun ; 9(1): 5190, 2018 12 05.
Article in English | MEDLINE | ID: mdl-30518844

ABSTRACT

Graphene has emerged as a promising material for optoelectronics due to its potential for ultrafast and broad-band photodetection. The photoresponse of graphene junctions is characterized by two competing photocurrent generation mechanisms: a conventional photovoltaic effect and a more dominant hot-carrier-assisted photothermoelectric (PTE) effect. The PTE effect is understood to rely on variations in the Seebeck coefficient through the graphene doping profile. A second PTE effect can occur across a homogeneous graphene channel in the presence of an electronic temperature gradient. Here, we study the latter effect facilitated by strongly localised plasmonic heating of graphene carriers in the presence of nanostructured electrical contacts resulting in electronic temperatures of the order of 2000 K. At certain conditions, the plasmon-induced PTE photocurrent contribution can be isolated. In this regime, the device effectively operates as a sensitive electronic thermometer and as such represents an enabling technology for development of hot carrier based plasmonic devices.

12.
J Med Ethics ; 44(4): 270-276, 2018 04.
Article in English | MEDLINE | ID: mdl-29127137

ABSTRACT

Though antiretroviral therapy is the standard of care for people living with HIV, its treatment limitations, burdens, stigma and costs lead to continued interest in HIV cure research. Early-phase cure trials, particularly those that include analytic treatment interruption (ATI), involve uncertain and potentially high risk, with minimal chance of clinical benefit. Some question whether such trials should be offered, given the risk/benefit imbalance, and whether those who choose to participate are acting rationally. We address these questions through a longitudinal decision-making study nested in a Thai acute HIV research cohort.In-depth interviews revealed central themes about decisions to join. Participants felt they possessed an important identity as members of the acute cohort, viewing their bodies as uniquely suited to both testing and potentially benefiting from HIV cure approaches. While acknowledging risks of ATI, most perceived they were given an opportunity to interrupt treatment, to test their own bodies and increase normalcy in a safe, highly monitored circumstance. They were motivated by potential benefits to themselves, the investigators and larger acute cohort, and others with HIV. They believed their own trial experiences and being able to give back to the community were sufficient to offset participation risks.These decisions were driven by the specific circumstances experienced by our participants. Judging risk/benefit ratios without appreciating these lived experiences can lead to false determinations of irrational decision- making. While this does not minimise vital oversight considerations about risk reduction and protection from harm, it argues for inclusion of a more participant-centered approach.


Subject(s)
AIDS Vaccines , Biomedical Research , Clinical Trials as Topic/ethics , HIV Infections/drug therapy , Therapeutic Human Experimentation/ethics , Withholding Treatment/ethics , Adult , Anti-HIV Agents , Decision Making , Female , HIV Infections/transmission , Health Knowledge, Attitudes, Practice , Health Services Research , Humans , Male , Middle Aged , Patient Participation , Patient Rights , Risk Assessment , Viral Load/drug effects
13.
AIDS Res Hum Retroviruses ; 34(1): 56-66, 2018 01.
Article in English | MEDLINE | ID: mdl-29198134

ABSTRACT

Global interest and investment in the search for an HIV cure has increased. Research has focused on what experts refer to as a sterilizing or eradicating cure, where HIV is eliminated from the body, and on what is often called a functional cure, where HIV remains, kept durably suppressed in the absence of antiretroviral treatment and therapy (ART). Many believe that a functional cure is likely to be found first. HIV cure studies will require active participation by people living with HIV (PLWHIV). Their desires and perceptions will be important to effectively recruit study participants and for the uptake of any future strategy that demonstrates safety and efficacy. The perspectives of PLWHIV are essential to advancing HIV cure research, and they should be taken into consideration as biomedical research advances. We conducted 10 focus groups in four U.S. cities, eliciting perspectives of PLWHIV on HIV cure and cure research. Most participants conceived of a cure as eradicating, and felt favorably toward it. In addition to the physical benefits of a potential cure, participants valued the possible de-stigmatization related to no longer living with HIV, liberation from concerns about transmitting HIV, and freedom from the burden of daily medication. Many participants did not regard a functional cure as an improvement over controlling HIV through ART, were distrustful about viral rebound potential, and noted concerns about medical complications and accompanying psychological distress. Some felt that the risks of HIV cure research were not worth taking. Many were skeptical about science's ability to eliminate HIV from the body.


Subject(s)
Biomedical Research , Focus Groups , HIV Infections/drug therapy , HIV Infections/psychology , Adolescent , Adult , Aged , Anti-Retroviral Agents/therapeutic use , Cities , Female , HIV , Humans , Male , Middle Aged , Qualitative Research , United States , Young Adult
14.
J Virus Erad ; 3(2): 82-84, 2017 Apr 01.
Article in English | MEDLINE | ID: mdl-28435691

ABSTRACT

Over the past several years there has been intense activity directed at the possibility of achieving remission or eradication of HIV infection. Current assays for the measurement of latent HIV are insufficient to demonstrate complete clearance of replication-competent HIV. Therefore, the ultimate test for assessing whether investigational interventions have resulted in HIV remission or eradication is to interrupt standard antiretroviral therapy (ART) in a carefully controlled clinical trial setting. These procedures, known as analytic treatment interruptions (ATIs), raise important scientific and ethical questions. The lack of definitive assays for measuring viral reservoirs not only makes research on HIV remission or cure challenging, it also affects the ability to assess risks from ATIs themselves. In spite of these challenges, basic ethical criteria can be met with careful study design and close monitoring. In this brief report we outline ethical standards for HIV cure research involving ATIs. These criteria should be revisited as the science evolves.

16.
Am J Bioeth ; 16(10): 3-11, 2016 10.
Article in English | MEDLINE | ID: mdl-27653388

ABSTRACT

Military metaphors are pervasive in biomedicine, including HIV research. Rooted in the mind set that regards pathogens as enemies to be defeated, terms such as "shock and kill" have become widely accepted idioms within HIV cure research. Such language and symbolism must be critically examined as they may be especially problematic when used to express scientific ideas within emerging health-related fields. In this article, philosophical analysis and an interdisciplinary literature review utilizing key texts from sociology, anthropology, history, and Chinese and African studies were conducted to investigate the current proliferation of military metaphors. We found the use of these metaphors to be ironic, unfortunate, and unnecessary. To overcome military metaphors we propose to (1) give them less aggressive meanings, and/or (2) replace them with more peaceful metaphors. Building on previous authors' work, we argue for the increased use of "journey" (and related) metaphors as meaningful, cross-culturally appropriate alternatives to military metaphors.


Subject(s)
HIV Infections/drug therapy , Metaphor , Military Medicine , Humans , Military Personnel
17.
Sci Rep ; 6: 30210, 2016 07 22.
Article in English | MEDLINE | ID: mdl-27443219

ABSTRACT

We report a CVD hexagonal boron nitride (hBN-) assisted transfer method that enables a polymer-impurity free transfer process and subsequent top encapsulation of large-area CVD-grown graphene. We demonstrate that the CVD hBN layer that is utilized in this transfer technique acts as a buffer layer between the graphene film and supporting polymer layer. We show that the resulting graphene layers possess lower doping concentration, and improved carrier mobilities compared to graphene films produced by conventional transfer methods onto untreated SiO2/Si, SAM-modified and hBN covered SiO2/Si substrates. Moreover, we show that the top hBN layer used in the transfer process acts as an effective top encapsulation resulting in improved stability to ambient exposure. The transfer method is applicable to other CVD-grown 2D materials on copper foils, thereby facilitating the preparation of van der Waals heterostructures with controlled doping.

18.
J Virus Erad ; 2: 49-51, 2016.
Article in English | MEDLINE | ID: mdl-26966553

ABSTRACT

Women are underrepresented in HIV cure research. In this paper we discuss the rationale for including women and propose multilevel strategies to improve sex equity in HIV cure research. The inadequate inclusion of women in HIV cure research is concerning for both scientific and ethical reasons. Biological responses to HIV and HIV treatment, as well as social contexts, differ between men and women, and this may affect the efficacy of curative interventions. Strategies for improving sex equity in HIV cure research include addressing eligibility criteria, adapting recruitment strategies, engaging community members early in the research process, and promoting funder policy changes. We conclude by describing the Gender, Race, and Clinical Experience (GRACE) study, which is one example of how women can be effectively recruited into HIV-related clinical trials. While HIV cure research is currently in the early stages, as it continues to develop it is important to mobilise for adequate inclusion of women.

19.
BMC Infect Dis ; 16: 109, 2016 Mar 03.
Article in English | MEDLINE | ID: mdl-26939697

ABSTRACT

BACKGROUND: Curing HIV is a new strategic priority for several major AIDS organizations. In step with this new priority, HIV cure research and related programs are advancing in low, middle, and high-income country settings. This HIV cure momentum may influence existing HIV programs and research priorities. DISCUSSION: Despite the early stage of ongoing HIV cure efforts, these changes have directly influenced HIV research funding priorities, pilot programs, and HIV messaging. The building momentum to cure HIV infection may synergize with strategic priorities to better identify adults and infants with very early HIV infection. Although HIV cure represents a new goal, many existing programs and research techniques can be repurposed towards an HIV cure. HIV messages focused on engaging communities towards an HIV cure need to be careful to promote ARV adherence and retention within the HIV continuum of care. An increased emphasis within the AIDS field on finding an HIV cure has several important implications. Strengthening connections between HIV cure research and other areas of HIV research may help to catalyze research and facilitate implementation in the future.


Subject(s)
Biomedical Research , HIV Infections , Biomedical Research/economics , Biomedical Research/trends , Global Health , HIV Infections/drug therapy , HIV Infections/economics , HIV Infections/prevention & control , Humans , Public Health
20.
Nano Lett ; 15(5): 3458-64, 2015 May 13.
Article in English | MEDLINE | ID: mdl-25915785

ABSTRACT

Hybrid plasmonic metal-graphene systems are emerging as a class of optical metamaterials that facilitate strong light-matter interactions and are of potential importance for hot carrier graphene-based light harvesting and active plasmonic applications. Here we use femtosecond pump-probe measurements to study the near-field interaction between graphene and plasmonic gold nanodisk resonators. By selectively probing the plasmon-induced hot carrier dynamics in samples with tailored graphene-gold interfaces, we show that plasmon-induced hot carrier generation in the graphene is dominated by direct photoexcitation with minimal contribution from charge transfer from the gold. The strong near-field interaction manifests as an unexpected and long-lived extrinsic optical anisotropy. The observations are explained by the action of highly localized plasmon-induced hot carriers in the graphene on the subresonant polarizability of the disk resonator. Because localized hot carrier generation in graphene can be exploited to drive electrical currents, plasmonic metal-graphene nanostructures present opportunities for novel hot carrier device concepts.

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