Coupling of non-crossing wave modes in a two-dimensional plasma crystal

We report an experimental observation of coupling of the transverse vertical and longitudinal in-plane dust-lattice wave modes in a two-dimensional complex plasma crystal in the absence of mode crossing. A new large diameter rf plasma chamber was used to suspend the plasma crystal. The observations are confirmed with molecular-dynamics simulations. The coupling manifests itself in traces of the transverse vertical mode appearing in the measured longitudinal spectra and vice versa. We calculate the expected ratio of the trace to the principal mode with a theoretical analysis of the modes in a crystal with finite temperature and find good agreement with the experiment and simulations.Comment: 4 figures, 5 pages, accepted for publication in PRL Nov 201

Wake-mediated propulsion of an upstream particle in two-dimensional plasma crystals

The wake-mediated propulsion of an "extra" particle in a channel of two neighboring rows of a two-dimensional plasma crystal, observed experimentally by Du et al. [Phys. Rev. E 89, 021101(R) (2014)], is explained in simulations and theory. We use the simple model of a pointlike ion wake charge to reproduce this intriguing effect in simulations, allowing for a detailed investigation and a deeper understanding of the underlying dynamics. We show that the nonreciprocity of the particle interaction, owing to the wake charges, is responsible for a broken symmetry of the channel that enables a persistent self-propelled motion of the extra particle. We find good agreement of the terminal extra-particle velocity with our theoretical considerations and with experiments.Comment: 7 pages, 4 figures, PRL (https://journals.aps.org/prl/), updated version with correct author affiliation

Long term global trends in open access. A data paper

Studies on long term trends in open access are of interest for the assessment of the evolution of scientific publishing and related markets. We therefore compiled and analysed a data set that integrated Web of Science as a global bibliographic data source on internationally relevant publications with data from Unpaywall, the primary provider of information related to open access at publication level. Data were captured in 2021 and show the open access categories as defined by Unpaywall for the publication years 2000 to 2020. In these two decades open access has gained substantial momentum. Starting with a few per cent, it now covers roughly half of the publications when embargo periods are over. The comparison of four variants of subsets of these data, however, show the wide variability in absolute and relative numbers. Results depend heavily on the characteristics of the data sources and the subsets selected within these. Major factors are listed and discussed. Aggregated data are provided in the MPG data repository

Network analysis of 3D complex plasma clusters in a rotating electric field

Network analysis was used to study the structure and time evolution of driven three-dimensional complex plasma clusters. The clusters were created by suspending micron-size particles in a glass box placed on top of the rf electrode in a capacitively coupled discharge. The particles were highly charged and manipulated by an external electric field that had a constant magnitude and uniformly rotated in the horizontal plane. Depending on the frequency of the applied electric field, the clusters rotated in the direction of the electric field or remained stationary. The positions of all particles were measured using stereoscopic digital in-line holography. The network analysis revealed the interplay between two competing symmetries in the cluster. The rotating cluster was shown to be more cylindrical than the nonrotating cluster. The emergence of vertical strings of particles was also confirmed.Comment: 9 pages, 9 figures; corrected Fig.4 and typo

Associations between HIV-RNA-based indicators and virological and clinical outcomes

OBJECTIVES: To evaluate and compare the performance of six HIV-RNA-based quality of care indicators for predicting short-term and long-term outcomes. DESIGN: Multinational cohort study. METHODS: We included EuroSIDA patients on antiretroviral therapy (ART) with ≥3viral load (VL) measurements after baseline (the latest of 01/01/2001 or entry into EuroSIDA). Using multivariate Poisson regression we modelled the association between short-term (resistance, triple-class failure) and long-term (all-cause mortality, any AIDS/non-AIDS clinical event) outcomes and the indicators: (i)viraemia copy years (VCY), (ii) Consecutive months with VL ≥50 copies/mL, (iii) percentage of time on ART spent fully suppressed (%FS), (iv) stable on ART, (v)48 weeks snapshot, and (vi) current VL. Indicators were compared using area under the ROC curve (AUC) and different measures of model fit. RESULTS: Adjusted incidence rate ratios for all outcomes tended to increase with increasing VCY, number of consecutive months with VL ≥50 copies/mL, current VL and with lower %FS, but the gradient of increased risk was weak across strata. None of the indicators reliably identified those at risk of long-term outcomes (AUC 0.54-0.58), but performed consistently better with short-term outcomes (triple class failure [AUC 0.67-0.76]) and resistance [AUC 0.64-0.79]). Goodness of fitvariedwith the outcome evaluated, but differences between indicators were small. CONCLUSIONS: Differences between quality of care indicators were small and no indicator performed consistently better than current VL. Given the simplicity in assessing and interpreting this indicator, wepropose to use current VL when HIV-RNA-based indicators are used to evaluate the efficacy of ART programs

Long-term effectiveness of unboosted atazanavir plus abacavir/lamivudine in subjects with virological suppression: A prospective cohort study

Effectiveness data of an unboosted atazanavir (ATV) with abacavir/lamivudine (ABC/3TC) switch strategy in clinical routine are scant.We evaluated treatment outcomes of ATV + ABC/3TC in pretreated subjects in the EuroSIDA cohort when started with undetectable plasma HIV-1 viral load (pVL), performing a time to loss of virological response (TLOVR 50 copies/mL.We included 285 subjects, 67% male, with median baseline CD4 530 cells, and 44 months with pVL ≤50 copies/mL. The third drug in the previous regimen was ritonavir-boosted atazanavir (ATV/r) in 79 (28%), and another ritonavir-boosted protease inhibitor (PI/r) in 29 (10%). Ninety (32%) had previously failed with a PI. Proportions of people with virological success at 48/96/144 weeks were 90%/87%/88% (TLOVR) and 74%/67%/59% (snapshot analysis), respectively. The rates of VF were 8%/8%/6%. Rates of adverse events leading to study discontinuation were 0.4%/1%/2%. The multivariable adjusted analysis showed an association between VF and nadir CD4+ (hazard ratio [HR] 0.63 [95% confidence interval [CI]: 0.42-0.93] per 100 cells higher), time with pVL ≤50 copies/mL (HR 0.87 [95% CI: 0.79-0.96] per 6 months longer), and previous failure with a PI (HR 2.78 [95% CI: 1.28-6.04]). Resistance selection at failure was uncommon.A switch to ATV + ABC/3TC in selected subjects with suppressed viremia was associated with low rates of VF and discontinuation due to adverse events, even in subjects not receiving ATV/r. The strategy might be considered in those with long-term suppression and no prior PI failure

Network analysis of 3D complex plasma clusters

Network analysis was used to study the structure and time evolution of driven three-dimensional complex plasma clusters. The clusters were created by suspending micron-size particles in a glass box placed on top of the rf electrode in a capacitively coupled discharge. The particles were highly charged and manipulated by an external electric �eld that had a constant magnitude and rotated uniformly in the horizontal plane. Depending on the frequency of the applied electric �eld, the clusters rotated in the direction of the electric �eld or remained stationary. The three-dimensional positions of all particles were measured using stereoscopic digital in-line holography. The network approach was used to elucidate the structural changes in the cluster consisting only of a very limited number of particles (64). The Analysis revealed an interplay between two competing symmetries in the cluster. Spherical and cylindrical ordering of the particles was examined by comparing network measures of the experimental data with null models. The null models were arti�cial data with a certain number of points in perfectly spherical order, and the rest in cylindrical order. The well established network measures local connectivity, clustering coe�cient and average path length were considered. Network analysis of the clusters showed that the rotating cluster was more cylindrical than the nonrotating cluster. These �ndings were in agreement with the estimate of the radial con�nement with the aid of a dynamical force balance. Neglecting friction and inertial forces due to the low particle velocities in the cluster, the pro�le of the electrical con�nement could be estimated by calculating the repulsing Yukawa-type interaction between the particles. The radial con�nement was shown to be stronger in the case of cluster rotation, increasing the cylindricity of the cluster. The emergence of vertical strings of particles was also con�rmed by using a network analysis. While the traditional method of a �xed threshold has limitations such as erroneously including passing by particles and a somewhat arbitrary threshold, community �nding algorithms yield a more elegant approach of �nding structures in complex systems. With the aid of multislice networks, it is possible to examine the whole time series at once and thus resolve the time evolution of the strings. As we demonstrated, network analysis is a powerful tool to analyze the structure of complex plasma clusters and may have numerous applications in other complex systems where the characertization of the spatial structure plays a vital role.

Disparities in HIV clinic care across Europe: findings from the EuroSIDA clinic survey

BACKGROUND: Although advances in HIV medicine have yielded increasingly better treatment outcomes in recent years, HIV-positive people with access to antiretroviral therapy (ART) still face complex health challenges. The EuroSIDA Study Group surveyed its clinics to explore regional differences in clinic services. METHODS: The EuroSIDA study is a prospective observational cohort study that began enrolling patients in 1994. In early 2014, we conducted a 59-item survey of the 98 then-active EuroSIDA clinics. The survey covered HIV clinical care and other aspects of patient care. The EuroSIDA East Europe study region (Belarus, Estonia, Lithuania, the Russian Federation and Ukraine) was compared to a “non-East Europe” study region comprised of all other EuroSIDA countries. RESULTS: A larger proportion of clinics in the East Europe group reported deferring ART in asymptomatic patients until the CD4 cell count dropped below 350 cells/mm3 (75 % versus 25 %, p = 0.0032). Considerably smaller proportions of East Europe clinics reported that resistance testing was provided before ART initiation (17 % versus 86 %, p < 0.0001) and that it was provided upon treatment failure (58 % versus 90 %, p = 0.0040). Only 33 % of East Europe clinics reported providing hepatitis B vaccination, compared to 88 % of other clinics (p < 0.0001). Only 50 % of East Europe clinics reported having access to direct-acting antivirals for hepatitis C treatment, compared to 89 % of other clinics (p = 0.0036). There was significantly less tuberculosis/HIV treatment integration in the East Europe group (27 % versus 84 % p < 0.0001) as well as significantly less screening for cardiovascular disease (58 % versus 90 %, p = 0.014); tobacco use (50 % versus 93 %, p < 0.0001); alcohol consumption (50 % versus 93 %, p < 0.0001); and drug use (58 % versus 87 %, p = 0.029). CONCLUSIONS: Study findings demonstrate how specific features of HIV clinics differ across Europe. Significantly more East Europe clinics deferred ART in asymptomatic patients for longer, and significantly fewer East Europe clinics provided resistance testing before initiating ART or upon ART failure. The East Europe group of clinics also differed in regard to hepatitis B vaccination, direct-acting antiviral access, tuberculosis/HIV treatment integration and screening for other health issues. There is a need for further research to guide setting-specific decision-making regarding the optimal array of services at HIV clinics in Europe and worldwide

Long-term effectiveness of unboosted atazanavir plus abacavir/lamivudine in subjects with virological suppression : A prospective cohort study

Effectiveness data of an unboosted atazanavir (ATV) with abacavir/lamivudine (ABC/3TC) switch strategy in clinical routine are scant.We evaluated treatment outcomes of ATV + ABC/3TC in pretreated subjects in the EuroSIDA cohort when started with undetectable plasma HIV-1 viral load (pVL), performing a time to loss of virological response (TLOVR 50copies/mL.We included 285 subjects, 67% male, with median baseline CD4 530 cells, and 44 months with pVL 50copies/mL. The third drug in the previous regimen was ritonavir-boosted atazanavir (ATV/r) in 79 (28%), and another ritonavir-boosted protease inhibitor (PI/r) in 29 (10%). Ninety (32%) had previously failed with a PI. Proportions of people with virological success at 48/96/144 weeks were 90%/87%/88% (TLOVR) and 74%/67%/59% (snapshot analysis), respectively. The rates of VF were 8%/8%/6%. Rates of adverse events leading to study discontinuation were 0.4%/1%/2%. The multivariable adjusted analysis showed an association between VF and nadir CD4+ (hazard ratio [HR] 0.63 [95% confidence interval [CI]: 0.42-0.93] per 100 cells higher), time with pVL 50copies/mL (HR 0.87 [95% CI: 0.79-0.96] per 6 months longer), and previous failure with a PI (HR 2.78 [95% CI: 1.28-6.04]). Resistance selection at failure was uncommon.A switch to ATV + ABC/3TC in selected subjects with suppressed viremia was associated with low rates of VF and discontinuation due to adverse events, even in subjects not receiving ATV/r. The strategy might be considered in those with long-term suppression and no prior PI failure.Peer reviewe