Elastic electron scattering by laser-excited 138Ba( ... 6s6p 1P1) atoms

The results of a joint experimental and theoretical study concerning elastic electron scattering by laser-excited 138Ba( ... 6s6p 1P1) atoms are described. These studies demonstrate several important aspects of elastic electron collisions with coherently excited atoms, and are the first such studies. From the measurements, collision and coherence parameters, as well as cross sections associated with an atomic ensemble prepared with an arbitrary in-plane laser geometry and linear polarization (with respect to the collision frame), or equivalently with any magnetic sublevel superposition, have been obtained at 20 eV impact energy and at 10°, 15° and 20° scattering angles. The convergent close-coupling (CCC) method was used within the non-relativistic LS-coupling framework to calculate the magnetic sublevel scattering amplitudes. From these amplitudes all the parameters and cross sections at 20 eV impact energy were extracted in the full angular range in 1° steps. The experimental and theoretical results were found to be in good agreement, indicating that the CCC method can be reliably applied to elastic scattering by 138Ba( ... 6s6p 1P1) atoms, and possibly to other heavy elements when spin-orbit coupling effects are negligible. Small but significant asymmetry was observed in the cross sections for scattering to the left and to the right. It was also found that elastic electron scattering by the initially isotropic atomic ensemble resulted in the creation of significant alignment. As a byproduct of the present studies, elastic scattering cross sections for metastable 138Ba atoms were also obtained

Low-energy elastic electron scattering by acetylene

We report measurements and first-principles calculations of the differential cross sections for elastic scattering of low-energy electrons by acetylene, C_2H_2, at collision energies from 1 to 100 eV, with an emphasis on energies near and below that of the π* shape resonance. The measurements cover angles from 5° to 130°. We compare our results to previous experimental and theoretical values

Low-energy electron scattering from methanol and ethanol

Measured and calculated differential cross sections for elastic (rotationally unresolved) electron scattering from two primary alcohols, methanol (CH3OH) and ethanol (C2H5OH), are reported. The measurements are obtained using the relative flow method with helium as the standard gas and a thin aperture as the collimating target gas source. The relative flow method is applied without the restriction imposed by the relative flow pressure conditions on helium and the unknown gas. The experimental data were taken at incident electron energies of 1, 2, 5, 10, 15, 20, 30, 50, and 100 eV and for scattering angles of 5°–130°. There are no previous reports of experimental electron scattering differential cross sections for CH3OH and C2H5OH in the literature. The calculated differential cross sections are obtained using two different implementations of the Schwinger multichannel method, one that takes all electrons into account and is adapted for parallel computers, and another that uses pseudopotentials and considers only the valence electrons. Comparison between theory and experiment shows that theory is able to describe low-energy electron scattering from these polyatomic targets quite well

Multiple scattering approach to elastic electron collisions with molecular clusters

We revisit our multiple-scattering method to treat low energy elastic electron collisions with (H2O)2. Calculations are performed for different geometries of the water dimer with different dipole moments. The effect of the dipole moment of the cluster is analysed. The elastic cross sections are compared to R-matrix results. Good agreement is found above 1 eV for all geometries. Results conrm the validity of the technique

Measurements of Airborne Influenza Virus in Aerosol Particles from Human Coughs

Influenza is thought to be communicated from person to person by multiple pathways. However, the relative importance of different routes of influenza transmission is unclear. To better understand the potential for the airborne spread of influenza, we measured the amount and size of aerosol particles containing influenza virus that were produced by coughing. Subjects were recruited from patients presenting at a student health clinic with influenza-like symptoms. Nasopharyngeal swabs were collected from the volunteers and they were asked to cough three times into a spirometer. After each cough, the cough-generated aerosol was collected using a NIOSH two-stage bioaerosol cyclone sampler or an SKC BioSampler. The amount of influenza viral RNA contained in the samplers was analyzed using quantitative real-time reverse-transcription PCR (qPCR) targeting the matrix gene M1. For half of the subjects, viral plaque assays were performed on the nasopharyngeal swabs and cough aerosol samples to determine if viable virus was present. Fifty-eight subjects were tested, of whom 47 were positive for influenza virus by qPCR. Influenza viral RNA was detected in coughs from 38 of these subjects (81%). Thirty-five percent of the influenza RNA was contained in particles \u3e4 µm in aerodynamic diameter, while 23% was in particles 1 to 4 µm and 42% in particles \u3c1 µm. Viable influenza virus was detected in the cough aerosols from 2 of 21 subjects with influenza. These results show that coughing by influenza patients emits aerosol particles containing influenza virus and that much of the viral RNA is contained within particles in the respirable size range. The results support the idea that the airborne route may be a pathway for influenza transmission, especially in the immediate vicinity of an influenza patient. Further research is needed on the viability of airborne influenza viruses and the risk of transmission

Low-energy elastic electron scattering by acetaldehyde

We report results from a combined experimental and computational study of low-energy electron interactions with acetaldehyde in the gas phase. Differential cross sections for elastic electron scattering were measured at selected incident energies from 1 to 50 eV, while corresponding first-principles calculations were carried out up to 30 eV. Integral and momentum-transfer cross sections were derived from the angle-differential data. The role of resonances in the scattering is examined and comparison is made to previous results for acetaldehyde and for its analogs, formamide and formic acid

Genome-to-genome analysis highlights the effect of the human innate and adaptive immune systems on the hepatitis C virus

Outcomes of hepatitis C virus (HCV) infection and treatment depend on viral and host genetic factors. Here we use human genome-wide genotyping arrays and new whole-genome HCV viral sequencing technologies to perform a systematic genome-to-genome study of 542 individuals who were chronically infected with HCV, predominantly genotype 3. We show that both alleles of genes encoding human leukocyte antigen molecules and genes encoding components of the interferon lambda innate immune system drive viral polymorphism. Additionally, we show that IFNL4 genotypes determine HCV viral load through a mechanism dependent on a specific amino acid residue in the HCV NS5A protein. These findings highlight the interplay between the innate immune system and the viral genome in HCV control

Diagnosis and Management of Opsoclonus-Myoclonus-Ataxia Syndrome in Children: An International Perspective.

BACKGROUND AND OBJECTIVES Opsoclonus-myoclonus-ataxia syndrome (OMAS) is a rare disorder of the nervous system that classically presents with a combination of characteristic eye movement disorder and myoclonus, in addition to ataxia, irritability, and sleep disturbance. There is good evidence that OMAS is an immune-mediated condition that may be paraneoplastic in the context of neuroblastoma. This syndrome may be associated with long-term cognitive impairment, yet it remains unclear how this is influenced by disease course and treatment. Treatment is largely predicated on immune suppression, but there is limited evidence to indicate an optimal regimen. METHODS Following an international multiprofessional workshop in 2004, a body of clinicians and scientists comprising the International OMS Study group continued to meet biennially in a joint professionals and family workshop focusing on pediatric OMAS. Seventeen years after publication of the first report, a writing group was convened to provide a clinical update on the definitions and clinical presentation of OMAS, biomarkers and the role of investigations in a child presenting with OMAS, treatment and management strategies including identification and support of long-term sequelae. RESULTS The clinical criteria for diagnosis were reviewed, with a proposed approach to laboratory and radiologic investigation of a child presenting with possible OMAS. The evidence for an upfront vs escalating treatment regimen was reviewed, and a treatment algorithm proposed to recognize both these approaches. Importantly, recommendations on monitoring of immunotherapy response and longer-term follow-up based on an expert consensus are provided. DISCUSSION OMAS is a rare neurologic condition that can be associated with poor cognitive outcomes. This report proposes an approach to investigation and treatment of children presenting with OMAS, based on expert international opinion recognizing the limited data available

UK-Wide Multicenter Evaluation of Second-line Therapies in Primary Biliary Cholangitis

Background & Aims: Thirty-to-forty percent of patients with primary biliary cholangitis inadequately respond to ursodeoxycholic acid. Our aim was to assemble national, real-world data on the effectiveness of obeticholic acid (OCA) as a second-line treatment, alongside non-licensed therapy with fibric acid derivatives (bezafibrate or fenofibrate). Methods: This was a nationwide observational cohort study conducted from August 2017 until June 2021. Results: We accrued data from 457 patients; 349 treated with OCA and 108 with fibric acid derivatives. At baseline/pre-treatment, individuals in the OCA group manifest higher risk features compared with those taking fibric acid derivatives, evidenced by more elevated alkaline phosphatase values, and a larger proportion of individuals with cirrhosis, abnormal bilirubin, prior non-response to ursodeoxycholic acid, and elastography readings >9.6kPa (P <.05 for all). Overall, 259 patients (OCA) and 80 patients (fibric acid derivatives) completed 12 months of second-line therapy, yielding a dropout rate of 25.7% and 25.9%, respectively. At 12 months, the magnitude of alkaline phosphatase reduction was 29.5% and 56.7% in OCA and fibric acid groups (P <.001). Conversely, 55.9% and 36.4% of patients normalized serum alanine transaminase and bilirubin in the OCA group (P <.001). The proportion with normal alanine transaminase or bilirubin values in the fibric acid group was no different at 12 months compared with baseline. Twelve-month biochemical response rates were 70.6% with OCA and 80% under fibric acid treatment (P =.121). Response rates between treatment groups were no different on propensity-score matching or on sub-analysis of high-risk groups defined at baseline. Conclusion: Across the population of patients with primary biliary cholangitis in the United Kingdom, rates of biochemical response and drug discontinuation appear similar under fibric acid and OCA treatment

Time-dependent density functional study of the electronic spectra of oligoacenes in the charge states -1, 0, +1, and +2

We present a systematic theoretical study of the five smallest oligoacenes (naphthalene, anthracene, tetracene, pentacene, and hexacene) in their anionic,neutral, cationic, and dicationic charge states. We used density functional theory (DFT) to obtain the ground-state optimised geometries, and time-dependent DFT (TD-DFT) to evaluate the electronic absorption spectra. Total-energy differences enabled us to evaluate the electron affinities and first and second ionisation energies, the quasiparticle correction to the HOMO-LUMO energy gap and an estimate of the excitonic effects in the neutral molecules. Electronic absorption spectra have been computed by combining two different implementations of TD-DFT: the frequency-space method to study general trends as a function of charge-state and molecular size for the lowest-lying in-plane long-polarised and short-polarised $\pi\to\pi^\star$ electronic transitions, and the real-time propagation scheme to obtain the whole photo-absorption cross-section up to the far-UV. Doubly-ionised PAHs are found to display strong electronic transitions of $\pi\to\pi^\star$ character in the near-IR, visible, and near-UV spectral ranges, like their singly-charged counterparts. While, as expected, the broad plasmon-like structure with its maximum at about 17-18 eV is relatively insensitive to the charge-state of the molecule, a systematic decrease with increasing positive charge of the absorption cross-section between about 6 and about 12 eV is observed for each member of the class.Comment: 38 pages, 11 figures, 7 tables, accepted for publication in Chemical Physic