First Direct Measurement of

Type-I x-ray bursts can reveal the properties of an accreting neutron star system when compared with astrophysics model calculations. However, model results are sensitive to a handful of uncertain nuclear reaction rates, such as ^{22}Mg(α,p). We report the first direct measurement of ^{22}Mg(α,p), performed with the Active Target Time Projection Chamber. The corresponding astrophysical reaction rate is orders of magnitude larger than determined from a previous indirect measurement in a broad temperature range. Our new measurement suggests a less-compact neutron star in the source GS1826-24.

Erratum: Direct Observation of Proton Emission in

This corrects the article DOI: 10.1103/PhysRevLett.123.082501.

Direct Observation of Proton Emission in

The elusive ß^{-}p^{+} decay was observed in ^{11}Be by directly measuring the emitted protons and their energy distribution for the first time with the prototype Active Target Time Projection Chamber in an experiment performed at ISAC-TRIUMF. The measured ß^{-}p^{+} branching ratio is orders of magnitude larger than any previous theoretical model predicted. This can be explained by the presence of a narrow resonance in ^{11}B above the proton separation energy.

Nuclear Force Imprints Revealed on the Elastic Scattering of Protons with

How does nature hold together protons and neutrons to form the wide variety of complex nuclei in the Universe? Describing many-nucleon systems from the fundamental theory of quantum chromodynamics has been the greatest challenge in answering this question. The chiral effective field theory description of the nuclear force now makes this possible but requires certain parameters that are not uniquely determined. Defining the nuclear force needs identification of observables sensitive to the different parametrizations. From a measurement of proton elastic scattering on ^{10}C at TRIUMF and ab initio nuclear reaction calculations, we show that the shape and magnitude of the measured differential cross section is strongly sensitive to the nuclear force prescription.

Evidence of soft dipole resonance in

The first conclusive evidence of a dipole resonance in ^{11}Li having isoscalar character observed from inelastic scattering with a novel solid deuteron target is reported. The experiment was performed at the newly commissioned IRIS facility at TRIUMF. The results show a resonance peak at an excitation energy of 1.03±0.03 MeV with a width of 0.51±0.11 MeV (FWHM). The angular distribution is consistent with a dipole excitation in the distorted-wave Born approximation framework. The observed resonance energy together with shell model calculations show the first signature that the monopole tensor interaction is important in ^{11}Li. The first ab initio calculations in the coupled cluster framework are also presented.

Sequence of the nucleocapsid protein gene of subgroup A and B avian pneumoviruses.

The nucleocapsid protein (N) gene of two subgroup A and one subgroup B strains of avian pneumovirus has been cloned and sequenced. The gene of all three isolates comprised 1197 nucleotides (nt), which formed a single major open reading frame, potentially encoding a protein of 391 amino acid residues. The N gene of the two subgroup A isolates differed by only 1 nt but differed by 282 (24%) nt and 35 (11%) amino acids from the B isolate. The predicted protein was identical in length to that of human, bovine and ovine respiratory syncytial viruses, the amino acid identity being approximately 41% overall but with some regions of identity > 90%.

Nucleotide sequence of the matrix protein gene of a subgroup B avian pneumovirus.

The nucleotide sequence of the gene encoding the matrix protein of a subgroup B avian pneumovirus has been determined. The gene shows 73.5% homology with that of a subgroup A virus, with most differences occurring in the third codon position. Comparison with pneumovirus matrix proteins shows that the APV matrix protein retains the hydrophobic domain common to the others. The analysis indicates that the matrix protein gene can be used to differentiate the two APV subgroups.

Expression of the ORF-2 protein of the human respiratory syncytial virus M2 gene is initiated by a ribosomal termination-dependent reinitiation mechanism.

Translation of the open reading frame 2 (ORF-2) of the human respiratory syncytial virus M2 gene initiates at one of the three initiation codons located upstream of the termination codon for the first ORF. Replacement of ORF-2 with the major ORF of the chloramphenicol acetyltransferase reporter gene followed by systematic mutagenesis of the putative initiation codons demonstrated the usage of these codons as the translational initiators for ORF-2 expression both in vitro and in vivo. While the efficiency of translation was maintained when only the first and second AUG codons were preserved in vivo, there was no apparent preference in vitro for any of the three codons when only one was present. Mutagenesis studies showed that the location of the termination codon of ORF-1 protein plays a crucial role in directing translation of ORF-2 from the upstream initiation codons in vivo. This indicates that the second ORF is accessed by the ribosomes that are departing from the first ORF and that these ribosomes reinitiate on AUG codons 5' to the point of translation termination.

Lidar observations during dusty infrared Test-1.

Lidar measurements using ruby (0.7-microm) and CO(2) (10.6-microm) lidar systems during the dustry IR Test-1 are described. The test was conducted at the White Sands Missile Range (WSMR) in October 1978. Transmission comparisons are made between the two wavelengths through dust and smoke clouds generated by artillery barrages, TNT explosions, and oil-rubber fire in a test zone midway (1 km) along the lidar path. A target at the end of the lidar path provided a reference backscatter return for the transmission measurements. Results indicate that the broad particle size distribution present in the dust generated at WSMR produced little if any wavelength-dependent transmission effects.

Nucleotide sequences of the genes encoding the putative attachment glycoprotein (G) of mouse and tissue culture-passaged strains of pneumonia virus of mice.

The sequences of the genes encoding the putative attachment (G) proteins of pathogenic (strain J3666) mouse lung-passaged and nonpathogenic (strain 15) tissue culture-passaged strains of pneumonia virus of mice (PVM) have been determined. In both cases the major polypeptide was synthesised from the second open reading frame (ORF), a feature also found in the G gene of respiratory syncytial (RS) virus, another pneumovirus. However, the ORFs of the G genes of the two PVM strains were initiated at different nucleotide positions in the mRNA and comparison of hydrophobicity profiles revealed the presence of the putative amino-terminal cytoplasmic domain in the strain J3666 G protein and its absence in the predicted G protein of PVM strain 15. In common with the G protein of RS virus, the gene product of both PVM strains contained a high serine, threonine, and proline content. Indirect immunofluorescence analysis of BSC-1 cells expressing the G gene products confirmed the surface location of the proteins. Thus, the absence of a cytoplasmic domain does not interfere with the translocation of the G protein of PVM strain 15. In vitro translation of mRNA from the two PVM genes directed the synthesis of a larger polypeptide with the G gene of PVM strain J3666 than was seen with strain 15 G gene. In addition, a second protein was seen with strain J3666 mRNA which was the same size as the strain 15 G protein.

Rescue of synthetic minireplicons establishes the absence of the NS1 and NS2 genes from avian pneumovirus.

We have determined the nucleotide sequences of the regions 3' and 5' proximal to the avian pneumovirus (APV) N and L genes, respectively. These sequences were used in the construction of a synthetic minireplicon construct in which the chloramphenicol acetyltransferase (CAT) reporter gene was flanked at its 3' end with the APV leader together with the APV N gene start signal and at its 5' end with the APV L gene end signal and the genome trailer region. The ability of T7 RNA polymerase runoff transcripts to direct the replication and expression of the CAT reporter gene in APV-infected cells demonstrated the ability of the putative leader and trailer regions to direct genome replication and gene expression. Furthermore, this confirms the absence of the NS1 and NS2 gene analogs within the APV genome. We were able to detect the expression of CAT protein from cells that had been infected with supernatants from the initially infected and transfected cells. These results have identified the cis-acting sequences of APV responsible for viral replication, gene expression, and packaging into virus-like particles.

A single amino acid substitution in the phosphoprotein of respiratory syncytial virus confers thermosensitivity in a reconstituted RNA polymerase system.

The single amino acid change Gly172 to Ser in the phosphoprotein (P) of respiratory syncytial virus (RSV) has previously been shown to be responsible for the thermosensitivity and protein-negative phenotype of tsN19, a mutant of the B subgroup RSN-2 strain. This single change was inserted into the P gene of the A subgroup virus RSS-2, and the resulting phenotype was observed in a plasmid-driven reconstituted RSV RNA polymerase system. Expression from a genome analogue containing two reporter genes was thermosensitive when directed by plasmids containing the N, L, M2, and mutant P genes cloned under the control of T7 promoters. Analysis of RNA synthesis showed that mutant P protein was unable to produce genome, antigenome, or mRNA at the restrictive temperature. At a semipermissive temperature, genome, antigenome, and mRNA synthesis were all reduced, 6- to 30-fold, relative to synthesis directed by a wild-type P plasmid. Binding of the mutant P protein to N protein in the absence of other viral proteins was unaffected by temperature, indicating that the lesion did not produce a large enough structural change to disrupt this binding. These data suggest that the plasmid rescue system is suitable for investigation of the role of thermosensitive mutations in RSV polymerase components in RNA synthesis.

Nucleotide sequence of the gene encoding the viral polymerase of avian pneumovirus.

We report here the nucleotide sequence of the L gene of avian pneumovirus (APV). This is the second pneumovirus L gene and the second avian paramyxovirus L gene, following that of Newcastle disease virus, to be sequenced. The APV L gene is 6099 nucleotides long and encodes a single large ORF of 2004 amino acids. This makes the APV L protein the smallest to be described for any nonsegmented, negative-strand RNA virus. The protein contains six linear non-contiguous domains, a putative ATP-binding site and four polymerase motifs previously described for the L proteins of negative-strand RNA viruses. Phylogenetic analysis of domain III of 14 different L proteins suggests the pneumoviruses to be as distant in evolutionary terms from the other members of the Paramyxoviridae as are the Filoviridae.