ANTIGEN-SPECIFIC THYMUS CELL FACTORS IN THE GENETIC CONTROL OF THE IMMUNE RESPONSE TO POLY-(TYROSYL, GLUTAMYL)-POLY-D, L-ALANYL--POLY-LYSYL

The genetic control of the antibody response to a synthetic polypeptide antigen designated poly-L(Tyr, Glu)-poly-D,L-Ala--poly-L-Lys [(T, G)-A--L] has been studied in congenic high responder C3H.SW (H-2b) and low responder C3H/HeJ (H-2k) strains of mice. This response is controlled by the Ir-1 gene and is H-2 linked. The method employed was to study the ability of specifically primed or "educated" T cells of each strain to produce cooperative factors for (T, G)-A--L in vitro. Such factors have been shown to be capable of replacing the requirement for T cells in the thymus-dependent antibody response to (T, G)-A--L in vivo. The T-cell factors produced were tested for their ability to cooperate with B cells of either high or low responder origin by transfer together with bone marrow cells and (T, G)-A--L into heavily irradiated, syngeneic (for bone marrow donor) recipients. Direct anti-(T, G)-A--L plaque-forming cells were measured later in the spleens of the recipients. The results showed that (a) educated T cells of both high and low responder origin produced active cooperative factors to (T, G)-A--L, and no differences between the strains in respect to production of T-cell factors could be demonstrated; and (b) such factors, whether of high or low responder origin, cooperated efficiently with B cells of high responder origin only, and hardly at all with B cells of low responder origin. The conclusion was drawn that the cellular difference between the two strains lies in the responsiveness of their B cells to specific signals or stimuli received from T cells. As far as could be discerned by the methods used, no T-cell defect existed in low responder mice and the expression of the controlling Ir-1 gene was solely at the level of the B cells in this case

Electronic temperatures, densities and plasma X-ray emission of a 14.5 GHz Electron-Cyclotron Resonance Ion Source

We have performed a systematic study of the Bremsstrahlung emission from the electrons in the plasma of a commercial 14.5 GHz Electron-Cyclotron Resonance Ion Source. The electronic spectral temperature and the product of ionic and electronic densities of the plasma are measured by analyzing the Bremsstrahlung spectra recorded for several rare gases (Ar, Kr, Xe) as a function of the injected power. Within our uncertainty, we find an average temperature of ? 48 keV above 100W, with a weak dependency on the injected power and gas composition. Charge state distributions of extracted ion beams have been determined as well, providing a way to disentangle the ionic density from the electronic density. Moreover X-ray emission from highly charged argon ions in the plasma has been observed with a high-resolution mosaic crystal spectrometer, demonstrating the feasibility for high-precision measurements of transition energies of highly charged ions, in particular of the magnetic dipole (M1) transition of He-like of argon ions

Changes in context, typology and programme outcomes between early and recent periods of sex work among young female sex workers in Mombasa, Kenya: a cross-sectional study

INTRODUCTION: The sex work context and typology change continuously and influence HIV related risk and vulnerability for young female sex workers (YFSW). We sought to describe changes in the context and typology of sex work between the first (early) and past month (recent) of sex work among YFSW to inform HIV prevention programming for sex workers. METHODS: We used data from a cross-sectional survey (April-November 2015), administered using physical location-based sampling to 408 cis-women, aged 14-24 years, who self-identified as sex workers, in Mombasa, Kenya. We collected self-reported data on the early and recent month of sex work. The analysis focused on changes in a) sex work context and typology (defined by setting where sex workers practice sex work) where YFSW operated, b) primary typology of sex work, and c) HIV programme outcomes among YFSW who changed primary typology, within the early and recent month of sex work. We analysed the data using a) SPSS27.0 and excel; b) bivariate analysis and χ2 test; and c) bivariate logistic regression models. RESULTS: Overall, the median age of respondents was 20 years and median duration in sex work was 2 years. Higher proportion of respondents in the recent period managed their clients on their own (98.0% vs. 91.2%), had sex with >5 clients per week (39.3% vs.16.5%); were able to meet > 50% of living expenses through sex work income (46.8% vs. 18.8%); and experienced police violence in the past month (16.4% vs. 6.5%). YFSW reported multiple sex work typology in early and recent periods. Overall, 37.2% reported changing their primary typology. A higher proportion among those who used street/ bus stop typology, experienced police violence, or initiated sex work after 19 years of age in the early period reported a change. There was no difference in HIV programme outcomes among YFSW who changed typology vs. those who did not. CONCLUSIONS: The sex work context changes even in a short duration of two years. Hence, understanding these changes in the early period of sex work can allow for development of tailored strategies that are responsive to the specific needs and vulnerabilities of YFSW

A Strategic Location Model of Stationary Production Units: A Case study in the Albacora Leste field

The imminent interest in issues related to the oil and gas sector has always proved to be a profitable source of investment and research, with incremental gains and innovations in the various sectors of the offshore industry. Particularly in the context of resource localization, the adoption of mathematical models presents itself as a challenging theme. In this context, the research has the purpose of proposing a localization model of Stationary Production Units (SPU) of an oilfield located in the Campos Basin, Rio de Janeiro (Brazil). The computational tests were conducted using the Lingo software, based on data from the Albacora Leste field. The results of the proposed model demonstrated a reduction of approximately 12% in the configuration costs, compared to the current location

Reference-free measurements of the 1s 2s 2p 2PO1=2;3=2 ! 1s2 2s 2S1=2 and 1s 2s 2p 4P5=2 ! 1s2 2s 2S1=2 transition energies and widths in lithiumlike sulfur and argon ions

We have measured the widths and energies of the 1s2s2p 2 P 1/2,3/2 → 1s 2 2s 2 S 1/2 transitions in lithiumlike sulfur and argon, as well as the energies of the forbidden 1s2s2p 4 P 5/2 → 1s 2 2s 2 S 1/2 M2 transition in both elements. All measurements were performed with a double-flat crystal spectrometer without the use of any reference line. The transition energy measurements have accuracies ranging from 2.3 ppm to 6.4 ppm depending on the element and line intensity. The widths and the intensity ratios of the 1s2s2p 2 P 1/2,3/2 → 1s 2 2s 2 S 1/2 lines have also been measured. These are the first reference-free measurements of transitions in core-excited lithiumlike ions, and have an accuracy comparable to the best relative measurements. We have also performed multi-configuration Dirac-Fock calculations of the widths, energies and intensity ratios. Extensive comparison between existing experimental results and theory is performed, and Bayesian techniques employed to extract the energy of the 1s 2p 2 4 P 1/2 → 1s 2 2p 2 P 1/2 transition in sulfur and identify contaminant transitions

Ultrafast Hole Trapping and Relaxation Dynamics in p-Type CuS Nanodisks

CuS nanocrystals are potential materials for developing low-cost solar energy conversion devices. Understanding the underlying dynamics of photoinduced carriers in CuS nanocrystals is essential to improve their performance in these devices. In this work, we investigated the photoinduced hole dynamics in CuS nanodisks (NDs) using the combination of transient optical (OTA) and X-ray (XTA) absorption spectroscopy. OTA results show that the broad transient absorption in the visible region is attributed to the photoinduced hot and trapped holes. The hole trapping process occurs on a subpicosecond time scale, followed by carrier recombination (~100 ps). The nature of the hole trapping sites, revealed by XTA, is characteristic of S or organic ligands on the surface of CuS NDs. These results not only suggest the possibility to control the hole dynamics by tuning the surface chemistry of CuS but also represent the first time observation of hole dynamics in semiconductor nanocrystals using XTA

Reference-free measurements of the 1s2s2p 2 P1/2,3/2o →1s22s 2S1/2 and 1s2s2p 4P5/2→1s22s 2S1/2 transition energies and widths in lithiumlike sulfur and argon ions

PEstOE/FIS/UI0303/2011 PTDC/FIS/117606/2010 PTDC/FIS-AQM/31969/2017 UID/FIS/04559/2019 SFRH/BD/52332/2013 Contract No. EMMI HA-216 Hubert Curien PESSOA 38028UD PAUILF 2017-C08 Grant No. 01 3 0002 Grant No. ANR-06-BLAN-0223 Grant No. 70NANB15H051We have measured the widths and energies of the 1s2s2p2P1/2,3/2→1s22s2S1/2 transitions in lithiumlike sulfur and argon, as well as the energies of the forbidden 1s2s2p4P5/2→1s22s2S1/2 M2 transition in both elements. All measurements were performed with a double-flat-crystal spectrometer without the use of any reference line. The transition energy measurements have accuracies ranging from 2.3 to 6.4 ppm depending on the element and line intensity. The widths and the intensity ratios of the 1s2s2p2P1/2,3/2→1s22s2S1/2 lines have also been measured. These are reference-free measurements of transitions in core-excited lithiumlike ions and have an accuracy comparable to the best relative measurements. We have also performed multiconfiguration Dirac-Fock calculations of the widths, energies, and intensity ratios. An extensive comparison between existing experimental results and theory is performed, and Bayesian techniques are employed to extract the energy of the 1s2p24P1/2→1s22p2P1/2 transition in sulfur and identify contaminant transitions.publishersversionpublishe

HIV prevalence, testing and treatment among men who have sex with men through engagement in virtual sexual networks in Kenya: a cross-sectional bio-behavioural study

INTRODUCTION: In Kenya, men who have sex with men (MSM) are increasingly using virtual sites, including web-based apps, to meet sex partners. We examined HIV testing, HIV prevalence, awareness of HIV-positive status and linkage to antiretroviral therapy (ART), for HIV-positive MSM who solely met partners via physical sites (PMSM), compared with those who did so in virtual sites (either solely via virtual sites (VMSM), or via both virtual and physical sites (DMSM)). METHODS: We conducted a cross-sectional bio-behavioural survey of 1200 MSM, 15 years and above, in three counties in Kenya between May and July 2019, using random sampling of physical and virtual sites. We classified participants as PMSM, DMSM and VMSM, based on where they met sex partners, and compared the following between groups using chi-square tests: (i) proportion tested; (ii) HIV prevalence and (iii) HIV care continuum among MSM living with HIV. We then performed multivariable logistic regression to measure independent associations between network engagement and HIV status. RESULTS: 177 (14.7%), 768 (64.0%) and 255 (21.2%), of participants were classified as PMSM, DMSM and VMSM respectively. 68.4%, 70.4% and 78.5% of PMSM, DMSM and VMSM, respectively, reported an HIV test in the previous six months. HIV prevalence was 8.5% (PMSM), 15.4% (DMSM) and 26.7% (VMSM), p < 0.001. Among those living with HIV, 46.7% (PMSM), 41.5% (DMSM) and 29.4% (VMSM) were diagnosed and aware of their status; and 40.0%, 35.6% and 26.5% were on antiretroviral treatment. After adjustment for other predictors, MSM engaged in virtual networks remained at a two to threefold higher risk of prevalent HIV: VMSM versus PMSM (adjusted odds ratio 3.88 (95% confidence interval (CI) 1.84 to 8.17) p < 0.001); DMSM versus PMSM (2.00 (95% CI 1.03 to 3.87), p = 0.040). CONCLUSIONS: Engagement in virtual networks is associated with elevated HIV risk, irrespective of individual-level risk factors. Understanding the difference in characteristics among MSM-seeking partners in different sites will help HIV programmes to develop subpopulation-specific interventions

Assessing the influence of conflict on the dynamics of sex work and the HIV and HCV epidemics in Ukraine: protocol for an observational, ethnographic, and mathematical modeling study.

BACKGROUND: Armed conflict erupted in eastern Ukraine in 2014 and still continues. This conflict has resulted in an intensification of poverty, displacement and migration, and has weakened the local health system. Ukraine has some of the highest rates of HIV and Hepatitis C (HCV) in Europe. Whether and how the current conflict, and its consequences, will lead to changes in the HIV and HCV epidemic in Ukraine is unclear. Our study aims to characterize how the armed conflict in eastern Ukraine and its consequences influence the pattern, practice, and experience of sex work and how this affects HIV and HCV rates among female sex workers (FSWs) and their clients. METHODS: We are implementing a 5-year mixed methods study in Dnipro, eastern Ukraine. Serial mapping and size estimation of FSWs and clients will be conducted followed by bio-behavioral cross-sectional surveys among FSWs and their clients. The qualitative component of the study will include in-depth interviews with FSWs and other key stakeholders and participant diaries will be implemented with FSWs. We will also conduct an archival review over the course of the project. Finally, we will use these data to develop and structure a mathematical model with which to estimate the potential influence of changes due to conflict on the trajectory of HIV and HCV epidemics among FSW and clients. DISCUSSION: The limited data that exists on the effect of conflict on disease transmission provides mixed results. Our study will provide rigorous, timely and context-specific data on HIV and HCV transmission in the setting of conflict. This information can be used to inform the design and delivery of HIV and HCV prevention and care services

Assessing awareness and use of HIV self-testing kits after the introduction of a community-based HIV self-testing programme among men who have sex with men in Kenya

Men who have sex with men (MSM) bear a disproportionate burden of new HIV infections in Kenya, while experiencing discrimination, leading to suboptimal levels of HIV care. HIV self-testing (HIVST) is a tool to increase HIV screening and earlier diagnosis; however, questions remain regarding how best to scale-up HIVST to MSM in Kenya. The main objective of this study was to examine changes in knowledge and use of HIVST after implementation of a community-led HIVST project. Participants were MSM recruited from Kisumu, Mombasa, and Kiambu counties. Data were collected from two rounds (Round 1: 2019; Round 2: 2020) of serial cross-sectional integrated biological and behavioural assessments (IBBA), pre-, and post-project implementation. Two main outcomes were measured: 1) whether the respondent had ever heard of HIVST; and 2) whether they had ever used HIVST kits. Changes in outcomes between IBBA rounds were examined using modified multivariable Poisson regression models; adjusted prevalence ratios (aPR) and 95% confidence intervals (95% CI) are reported. A total of 2,328 respondents were included in main analyses. The proportion of respondents who had heard of HIVST increased from 75% in Round 1 to 94% in Round 2 (aPR: 1.2, 95% CI: 1.2-1.3), while those reporting using an HIVST kit increased from 20% to 53% (aPR: 2.3, 95% CI: 2.0-2.6). Higher levels of education and HIV programme awareness were associated with both outcomes. Awareness and use of HIVST kits increased after implementation of a community-led HIVST implementation project, demonstrating the importance of integration with existing community groups