Edge-induced excitations in Bi2Te3 from spatially-resolved electron energy-gain spectroscopy.

Among the many potential applications of topological insulator materials, their broad potential for the development of novel tunable plasmonics at THz and mid-infrared frequencies for quantum computing, terahertz detectors, and spintronic devices is particularly attractive. The required understanding of the intricate relationship between nanoscale crystal structure and the properties of the resulting plasmonic resonances remains, however, elusive for these materials. Specifically, edge- and surface-induced plasmonic resonances, and other collective excitations, are often buried beneath the continuum of electronic transitions, making it difficult to isolate and interpret these signals using techniques such as electron energy-loss spectroscopy (EELS). Here we focus on the experimentally clean energy-gain EELS region to characterise collective excitations in the topologically insulating material Bi2Te3 and correlate them with the underlying crystalline structure with nanoscale resolution. We identify with high significance the presence of a distinct energy-gain peak around -0.8eV, with spatially-resolved maps revealing that its intensity is markedly enhanced at the edge regions of the specimen. Our findings illustrate the reach of energy-gain EELS analyses to accurately map collective excitations in quantum materials, a key asset in the quest towards new tunable plasmonic devices.

Laboratory Diagnosis of Primary Amoebic Meningoencephalitis.

Primary amebic meningoencephalitis (PAM) is a fulminant fatal human disease caused by the free-living amoeba Naegleria fowleri. Infection occurs after inhalation of water containing the amoeba, typically after swimming in bodies of warm freshwater. N. fowleri migrates to the brain where it incites meningoencephalitis and cerebral edema leading to death of the patient 7 to 10 days postinfection. Although the disease is rare, it is almost always fatal and believed to be underreported. The incidence of PAM in countries other than the United States is unclear and possibly on track to being an emerging disease. Poor prognosis is caused by rapid progression, suboptimal treatment, and underdiagnosis. As diagnosis is often performed postmortem and testing is only performed by a few laboratories, more accessible testing is necessary. This article reviews the current methods used in the screening and confirmation of PAM and makes recommendations for improved diagnostic practices and awareness.

Interaction of chiral L-dialanine with Cu(100).

We report on the properties of the thin films of the short peptide L-dialanine grown on Cu(100) surfaces and compare them to those of L-alanine by using surface techniques like XPS, IRRAS and STM. The first dialanine monolayer, in contact with the metallic substrate, is found to consist of whole neutral molecules in the non-zwitterionic state forming a c(2 × 4) pattern with quasi-hexagonal symmetry. The peptide bond of dialanine is preserved in the adsorption state. The ordering of the L-dialanine overlayer is shown to replicate rearrangements of the atoms of the substrate around dislocations of the latter indicating a strong molecule-surface interaction. In the multilayer regime, molecules of the second and further layers are found to be in a zwitterionic state, readily desorbing even at room temperature. The first dialanine layer is tightly bound to the substrate, begins to desorb at temperatures higher than 390 K and cracks down at the surface, transforming into a new moiety, beyond 435 K.

Spatially Resolved Band Gap and Dielectric Function in Two-Dimensional Materials from Electron Energy Loss Spectroscopy.

The electronic properties of two-dimensional (2D) materials depend sensitively on the underlying atomic arrangement down to the monolayer level. Here we present a novel strategy for the determination of the band gap and complex dielectric function in 2D materials achieving a spatial resolution down to a few nanometers. This approach is based on machine learning techniques developed in particle physics and makes possible the automated processing and interpretation of spectral images from electron energy loss spectroscopy (EELS). Individual spectra are classified as a function of the thickness with K-means clustering, and then used to train a deep-learning model of the zero-loss peak background. As a proof of concept we assess the band gap and dielectric function of InSe flakes and polytypic WS2 nanoflowers and correlate these electrical properties with the local thickness. Our flexible approach is generalizable to other nanostructured materials and to higher-dimensional spectroscopies and is made available as a new release of the open-source EELSfitter framework.

Charting the low-loss region in electron energy loss spectroscopy with machine learning.

Exploiting the information provided by electron energy-loss spectroscopy (EELS) requires reliable access to the low-loss region where the zero-loss peak (ZLP) often overwhelms the contributions associated to inelastic scatterings off the specimen. Here we deploy machine learning techniques developed in particle physics to realise a model-independent, multidimensional determination of the ZLP with a faithful uncertainty estimate. This novel method is then applied to subtract the ZLP for EEL spectra acquired in flower-like WS2 nanostructures characterised by a 2H/3R mixed polytypism. From the resulting subtracted spectra we determine the nature and value of the bandgap of polytypic WS2, finding EBG=1.6-0.2+0.3eV with a clear preference for an indirect bandgap. Further, we demonstrate how this method enables us to robustly identify excitonic transitions down to very small energy losses. Our approach has been implemented and made available in an open source Python package dubbed EELSfitter.

Fifteen Years of Sm-p80-Based Vaccine Trials in Nonhuman Primates: Antibodies From Vaccinated Baboons Confer Protection in vivo and in vitro From Schistosoma mansoni and Identification of Putative Correlative Markers of Protection.

Recent advances in systems biology have shifted vaccine development from a largely trial-and-error approach to an approach that promote rational design through the search for immune signatures and predictive correlates of protection. These advances will doubtlessly accelerate the development of a vaccine for schistosomiasis, a neglected tropical disease that currently affects over 250 million people. For over 15 years and with contributions of over 120 people, we have endeavored to test and optimize Sm-p80-based vaccines in the non-human primate model of schistosomiasis. Using RNA-sequencing on eight different Sm-p80-based vaccine strategies, we sought to elucidate immune signatures correlated with experimental protective efficacy. Furthermore, we aimed to explore the role of antibodies through in vivo passive transfer of IgG obtained from immunized baboons and in vitro killing of schistosomula using Sm-p80-specific antibodies. We report that passive transfer of IgG from Sm-p80-immunized baboons led to significant worm burden reduction, egg reduction in liver, and reduced egg hatching percentages from tissues in mice compared to controls. In addition, we observed that sera from Sm-p80-immunized baboons were able to kill a significant percent of schistosomula and that this effect was complement-dependent. While we did not find a universal signature of immunity, the large datasets generated by this study will serve as a substantial resource for further efforts to develop vaccine or therapeutics for schistosomiasis.

Chronic whipworm infection exacerbates Schistosoma mansoni egg-induced hepatopathology in non-human primates.

BACKGROUND: Schistosomiasis continues to inflict significant morbidity and mortality in the tropical and subtropical regions of the world. The disease endemicity overlaps with the transmission of other parasitic diseases. Despite the ubiquity of polyparasitism in tropical regions, particularly in rural communities, little is known about the impact of multiple helminth infections on disease progression. In this pilot study, we describe the influence of chronic Trichuris trichiura infection on Schistosoma mansoni egg-induced hepatopathology in infected baboons. METHODS: Baboons with or without underlying whipworm infection were challenged with S. mansoni cercariae to establish schistosomiasis. Adult S. mansoni worms were recovered by perfusion and enumerated, hepatic granulomas were quantified via light microscopy, and transcriptional profiling of tissues were completed using RNA sequencing technologies. RESULTS: Co-infection with both S. mansoni and T. trichiura resulted in higher female schistosome worm burden and significantly larger liver granuloma sizes. Systems biology analyses of peripheral blood mononuclear cells (PBMC) revealed pathways associated with increased liver damage in co-infected baboons. CONCLUSIONS: Underlying chronic whipworm infection intensified schistosome egg-induced liver pathology in infected baboons. RNA-Seq analysis provided insight into pathways associated with increased liver damage, corroborating histological findings.

Can New Physics Hide inside the Proton?

Modern global analyses of the structure of the proton include collider measurements which probe energies well above the electroweak scale. While these provide powerful constraints on the parton distribution functions (PDFs), they are also sensitive to beyond the standard model (BSM) dynamics if these affect the fitted distributions. Here we present a first simultaneous determination of the PDFs and BSM effects from deep-inelastic structure function data by means of the NNPDF framework. We consider representative four-fermion operators from the SM effective field theory (SMEFT), quantify to which extent their effects modify the fitted PDFs, and assess how the resulting bounds on the SMEFT degrees of freedom are modified. Our results demonstrate how BSM effects that might otherwise be reabsorbed into the PDFs can be systematically disentangled.

Sm-p80-based schistosomiasis vaccine: double-blind preclinical trial in baboons demonstrates comprehensive prophylactic and parasite transmission-blocking efficacy.

Schistosomiasis is of public health importance to an estimated one billion people in 79 countries. A vaccine is urgently needed. Here, we report the results of four independent, double-blind studies of an Sm-p80-based vaccine in baboons. The vaccine exhibited potent prophylactic efficacy against transmission of Schistosoma mansoni infection and was associated with significantly less egg-induced pathology, compared with unvaccinated control animals. Specifically, the vaccine resulted in a 93.45% reduction of pathology-producing female worms and significantly resolved the major clinical manifestations of hepatic/intestinal schistosomiasis by reducing the tissue egg-load by 89.95%. A 35-fold decrease in fecal egg excretion in vaccinated animals, combined with an 81.51% reduction in hatching of eggs into the snail-infective stage (miracidia), demonstrates the parasite transmission-blocking potential of the vaccine. Substantially higher Sm-p80 expression in female worms and Sm-p80-specific antibodies in vaccinated baboons appear to play an important role in vaccine-mediated protection. Preliminary analyses of RNA sequencing revealed distinct molecular signatures of vaccine-induced effects in baboon immune effector cells. This study provides comprehensive evidence for the effectiveness of an Sm-p80-based vaccine for schistosomiasis.

Sm-p80-based vaccine trial in baboons: efficacy when mimicking natural conditions of chronic disease, praziquantel therapy, immunization, and Schistosoma mansoni re-encounter.

Sm-p80-based vaccine efficacy for Schistosoma mansoni was evaluated in a baboon model of infection and disease. The study was designed to replicate a human vaccine implementation scenario for endemic regions in which vaccine would be administered following drug treatment of infected individuals. In our study, the Sm-p80-based vaccine reduced principal pathology producing hepatic egg burdens by 38.0% and egg load in small and large intestines by 72.2% and 49.4%, respectively, in baboons. Notably, hatching rates of eggs recovered from liver and small and large intestine of vaccinated animals were significantly reduced, by 60.4%, 48.6%, and 82.3%, respectively. Observed reduction in egg maturation/hatching rates was supported by immunofluorescence and confocal microscopy showing unique differences in Sm-p80 expression in worms of both sexes and matured eggs. Vaccinated baboons had a 64.5% reduction in urine schistosome circulating anodic antigen, a parameter that reflects worm numbers/health status in infected hosts. Preliminary analyses of RNA sequencing revealed unique genes and canonical pathways associated with establishment of chronic disease, praziquantel-mediated parasite killing, and Sm-p80-mediated protection in vaccinated baboons. Overall, our study demonstrated efficacy of the Sm-p80 vaccine and provides insight into some of the epistatic interactions associated with protection.

Reactivity of a FeS Surface under Room Temperature Exposure to Nitrogen and H2S.

The reactivity of an iron monosulfide surface exposed at room temperature to molecular nitrogen and hydrogen sulfide has been investigated using X-ray photoemission spectroscopy (XPS) and thermal desorption spectroscopy (TDS). We have observed adsorption of nitrogen at room temperature that depends on the surface nanostructure and on the electronic state of nitrogen. The subsequent reaction of this adsorbed nitrogen with hydrogen sulfide results in depletion of the nitrogen surface content which can be interpreted in terms of ammonia formation. The XPS nitrogen N 1s core level line shape shows different components one of which seems to be the most reactive one in the ensuing H2S reaction.

Towards ultimate parton distributions at the high-luminosity LHC.

Since its start of data taking, the LHC has provided an impressive wealth of information on the quark and gluon structure of the proton. Indeed, modern global analyses of parton distribution functions (PDFs) include a wide range of LHC measurements of processes such as the production of jets, electroweak gauge bosons, and top quark pairs. In this work, we assess the ultimate constraining power of LHC data on the PDFs that can be expected from the complete dataset, in particular after the High-Luminosity (HL) phase, starting in around 2025. The huge statistics of the HL-LHC, delivering L = 3 ab - 1 to ATLAS and CMS and L = 0.3 ab - 1 to LHCb, will lead to an extension of the kinematic coverage of PDF-sensitive measurements as well as to an improvement in their statistical and systematic uncertainties. Here we generate HL-LHC pseudo-data for different projections of the experimental uncertainties, and then quantify the resulting constraints on the PDF4LHC15 set by means of the Hessian profiling method. We find that HL-LHC measurements can reduce PDF uncertainties by up to a factor of 2 to 4 in comparison to state-of-the-art fits, leading to few-percent uncertainties for important observables such as the Higgs boson transverse momentum distribution via gluon-fusion. Our results illustrate the significant improvement in the precision of PDF fits achievable from hadron collider data alone, and motivate the continuation of the ongoing successful program of PDF-sensitive measurements by the LHC collaborations.

Direct photon production and PDF fits reloaded.

Direct photon production in hadronic collisions provides a handle on the gluon PDF by means of the QCD Compton scattering process. In this work we revisit the impact of direct photon production on a global PDF analysis, motivated by the recent availability of the next-to-next-to-leading (NNLO) calculation for this process. We demonstrate that the inclusion of NNLO QCD and leading-logarithmic electroweak corrections leads to a good quantitative agreement with the ATLAS measurements at 8 and 13 TeV, except for the most forward rapidity region in the former case. By including the ATLAS 8 TeV direct photon production data in the NNPDF3.1 NNLO global analysis, we assess its impact on the medium-x gluon. We also study the constraining power of the direct photon production measurements on PDF fits based on different datasets, in particular on the NNPDF3.1 no-LHC and collider-only fits. We also present updated NNLO theoretical predictions for direct photon production at 13 TeV that include the constraints from the 8 TeV measurements.

Precision determination of the strong coupling constant within a global PDF analysis: NNPDF Collaboration.

We present a determination of the strong coupling constant α s ( m Z ) based on the NNPDF3.1 determination of parton distributions, which for the first time includes constraints from jet production, top-quark pair differential distributions, and the Z p T distributions using exact NNLO theory. Our result is based on a novel extension of the NNPDF methodology - the correlated replica method - which allows for a simultaneous determination of α s and the PDFs with all correlations between them fully taken into account. We study in detail all relevant sources of experimental, methodological and theoretical uncertainty. At NNLO we find α s ( m Z ) = 0.1185 ± 0 . 0005 (exp) ± 0 . 0001 (meth) , showing that methodological uncertainties are negligible. We conservatively estimate the theoretical uncertainty due to missing higher order QCD corrections (N 3 LO and beyond) from half the shift between the NLO and NNLO α s values, finding Δ α s th = 0.0011 .

Parton distributions with small-x resummation: evidence for BFKL dynamics in HERA data.

We present a determination of the parton distribution functions of the proton in which NLO and NNLO fixed-order calculations are supplemented by NLLx small-x resummation. Deep-inelastic structure functions are computed consistently at NLO+NLL x or NNLO+NLL x , while for hadronic processes small-x resummation is included only in the PDF evolution, with kinematic cuts introduced to ensure the fitted data lie in a region where the fixed-order calculation of the hard cross-sections is reliable. In all other respects, the fits use the same methodology and are based on the same global dataset as the recent NNPDF3.1 analysis. We demonstrate that the inclusion of small-x resummation leads to a quantitative improvement in the perturbative description of the HERA inclusive and charm-production reduced cross-sections in the small x region. The impact of the resummation in our fits is greater at NNLO than at NLO, because fixed-order calculations have a perturbative instability at small x due to large logarithms that can be cured by resummation. We explore the phenomenological implications of PDF sets with small-x resummation for the longitudinal structure function F L at HERA, for parton luminosities and LHC benchmark cross-sections, for ultra-high-energy neutrino-nucleus cross-sections, and for future high-energy lepton-proton colliders such as the LHeC.

Cross-species prophylactic efficacy of Sm-p80-based vaccine and intracellular localization of Sm-p80/Sm-p80 ortholog proteins during development in Schistosoma mansoni, Schistosoma japonicum, and Schistosoma haematobium.

Schistosomiasis remains a major global health problem. Despite large-scale schistosomiasis control efforts, clear limitations such as possible emergence of drug resistance and reinfection rates highlight the need for an effective schistosomiasis vaccine. Schistosoma mansoni large subunit of calpain (Sm-p80)-based vaccine formulations have shown remarkable efficacy in protecting against S. mansoni challenge infections in mice and baboons. In this study, we evaluated the cross-species protective efficacy of Sm-p80 vaccine against S. japonicum and S. haematobium challenge infections in rodent models. We also elucidated the expression of Sm-p80 and Sm-p80 ortholog proteins in different developmental stages of S. mansoni, S. haematobium, and S. japonicum. Immunization with Sm-p80 vaccine reduced worm burden by 46.75% against S. japonicum challenge infection in mice. DNA prime/protein boost (1 + 1 dose administered on a single day) resulted in 26.95% reduction in worm burden in S. haematobium-hamster infection/challenge model. A balanced Th1 (IFN-γ, TNF-α, IL-2, and IL-12) and Th2 (IL-4, IgG1) type of responses were observed following vaccination in both S. japonicum and S. haematobium challenge trials and these are associated with the prophylactic efficacy of Sm-p80 vaccine. Immunohistochemistry demonstrated that Sm-p80/Sm-p80 ortholog proteins are expressed in different life cycle stages of the three major human species of schistosomes studied. The data presented in this study reinforce the potential of Sm-p80-based vaccine for both hepatic/intestinal and urogenital schistosomiasis occurring in different geographical areas of the world. Differential expression of Sm-p80/Sm-p80 protein orthologs in different life cycle makes this vaccine potentially useful in targeting different levels of infection, disease, and transmission.

Higgs pair production in vector-boson fusion at the LHC and beyond.

The production of pairs of Higgs bosons at hadron colliders provides unique information on the Higgs sector and on the mechanism underlying electroweak symmetry breaking (EWSB). Most studies have concentrated on the gluon-fusion production mode which has the largest cross section. However, despite its small production rate, the vector-boson fusion channel can also be relevant since even small modifications of the Higgs couplings to vector bosons induce a striking increase of the cross section as a function of the invariant mass of the Higgs boson pair. In this work we exploit this unique signature to propose a strategy to extract the hhVV quartic coupling and provide model-independent constraints on theories where EWSB is driven by new strong interactions. We take advantage of the higher signal yield of the [Formula: see text] final state and make extensive use of jet-substructure techniques to reconstruct signal events with a boosted topology, characteristic of large partonic energies, where each Higgs boson decays to a single collimated jet. Our results demonstrate that the hhVV coupling can be measured with 45% (20%) precision at the LHC for [Formula: see text] (3000) fb[Formula: see text], while a 1% precision can be achieved at a 100 TeV collider.

A determination of the fragmentation functions of pions, kaons, and protons with faithful uncertainties: The NNPDF Collaboration.

We present NNFF1.0, a new determination of the fragmentation functions (FFs) of charged pions, charged kaons, and protons/antiprotons from an analysis of single-inclusive hadron production data in electron-positron annihilation. This determination, performed at leading, next-to-leading, and next-to-next-to-leading order in perturbative QCD, is based on the NNPDF methodology, a fitting framework designed to provide a statistically sound representation of FF uncertainties and to minimise any procedural bias. We discuss novel aspects of the methodology used in this analysis, namely an optimised parametrisation of FFs and a more efficient [Formula: see text] minimisation strategy, and validate the FF fitting procedure by means of closure tests. We then present the NNFF1.0 sets, and discuss their fit quality, their perturbative convergence, and their stability upon variations of the kinematic cuts and the fitted dataset. We find that the systematic inclusion of higher-order QCD corrections significantly improves the description of the data, especially in the small-z region. We compare the NNFF1.0 sets to other recent sets of FFs, finding in general a reasonable agreement, but also important differences. Together with existing sets of unpolarised and polarised parton distribution functions (PDFs), FFs and PDFs are now available from a common fitting framework for the first time.

Precision Determination of the Small-x Gluon from Charm Production at LHCb.

The small-x gluon in global fits of parton distributions is affected by large uncertainties from the lack of direct experimental constraints. In this Letter, we provide a precision determination of the small-x gluon from the exploitation of forward charm production data provided by LHCb for three different center-of-mass (c.m.) energies: 5 TeV, 7 TeV, and 13 TeV. The LHCb measurements are included in the parton distribution function (PDF) fit by means of normalized distributions and cross-section ratios between data taken at different c.m. values, R_{13/7} and R_{13/5}. We demonstrate that forward charm production leads to a reduction of the PDF uncertainties of the gluon down to x≃10^{-6} by up to an order of magnitude, with implications for high-energy colliders, cosmic ray physics, and neutrino astronomy.

Sm-p80-based schistosomiasis vaccine mediated epistatic interactions identified potential immune signatures for vaccine efficacy in mice and baboons.

Schistosomiasis is a neglected parasitic disease of major public health concern as it affects over 250 million people in developing countries. Currently there is no licensed vaccine available against schistosomiasis. The Schistosoma mansoni calpain protein, Sm-p80, is a leading vaccine candidate now ready to move to clinical trials. In order to better assess Sm-p80 vaccine immunogenicity; here we used a systems biology approach employing RNA-sequencing to identify gene signatures and epistatic interactions following Sm-p80 vaccination in mouse and baboon models that may predict vaccine efficacy. Recombinant Sm-p80 + CpG-oligodeoxynucleotide (ODN) vaccine formulation induced both cellular and humoral immunity genes with a predominant TH1 response as well as TH2 and TH17 gene signatures. Early gene responses and gene-network interactions in mice immunized with rSm-p80 + ODN appear to be initiated through TLR4 signaling. CSF genes, S100A alarmin genes and TNFRSF genes appear to be a signature of vaccine immunogenicity/efficacy as identified by their participation in gene network interactions in both mice and baboons. These gene families may provide a basis for predicting desirable outcomes for vaccines against schistosomiasis leading to a better understanding of the immune system response to vaccination.