Instrumentation availability during severe accidents for a boiling water reactor with a Mark I containment

In support of the US Nuclear Regulatory Commission Accident Management Research Program, the availability of instruments to supply accident management information during a broad range of severe accidents is evaluated for a Boiling Water Reactor with a Mark I containment. Results from this evaluation include: (1) the identification of plant conditions that would impact instrument performance and information needs during severe accidents; (2) the definition of envelopes of parameters that would be important in assessing the performance of plant instrumentation for a broad range of severe accident sequences; and (3) assessment of the availability of plant instrumentation during severe accidents

Risk management activities at the DOE Class A reactor facilities

The probabilistic risk assessment (PRA) and risk management group of the Association for Excellence in Reactor Operation (AERO) develops risk management initiatives and standards to improve operation and increase safety of the DOE Class A reactor facilities. Principal risk management applications that have been implemented at each facility are reviewed. The status of a program to develop guidelines for risk management programs at reactor facilities is presented

Perennial species for optimum production of herbaceous biomass in the Piedmont (Management study, 1987--1991)

The authors have investigated cutting and N management strategies for two biofuel feedstock candidate species -- switchgrass (Panicum virgatum) and weeping lovegrass (Eragrostis curvula). Each was no-till planted in 1987 at three sites underlain by Davidson or Cecil soils. Three N levels (0, 50, or 100 kg/ha) were applied, and the plots fertilized at each level were harvested either twice (early-September and early-November) or only in early-November. The results with lovegrass suggest 50 kg N/ha is nearly optimal and that two cuttings provide more biomass than one. For switchgrass, when averaged across sites and years, 50 kg N/ha produced a slight yield advantage over no added N, but 50 kg was not different from 100 kg. In 1989 and 1990, more biomass was available in early-September harvests (9.6 Mg/ha) than in early-November (8.3 Mg/ha). Apparently the plants translocated significant portions of their biomass below ground during the last few weeks of the season. In 1991, we harvested only in early-November. Plots that had been cut in early-September in the previous three years had lower yields (7.6 Mg/ha) than those that had been cut only in early-November (9.4 Mg/ha). The delayed cutting permitted more growth on a sustained basis -- presumably because of conservation of translocatable materials. This poses an interesting dilemma for the producer of biomass. In additional studies, the authors found no advantage in double-cropping rye (Secale cereale) with switchgrass; at low input levels, rye yields were low, and rye lowered switchgrass yields. Other studies showed double-cropping with winter-annual legumes such as crimson clover (Trifolium incarnatum) may have potential. The timing of herbicide treatment of the legume is critical

The strategic calculus of terrorism: Substitution and competition in the Israel—Palestine conflict

Previous work on the dynamics of conflicts where we see terrorism has tended to focus on whether we see shifts in attack mode following government countermeasures. We contend that many factors other than counterinsurgency can influence whether groups resort to terrorism, including competition between groups, as well as their relationship to public opinion and other political events. Hence, understanding terrorist tactics in prolonged conflicts with multiple actors requires us to consider a more general framework of innovation, imitation, competition and dependence between actors. We use disaggregated data on terrorist attacks, counterterrorism and public opinion in the Israel—Palestine conflict to jointly evaluate predictions derived from several conventional theories of strategic behaviour. We find that the strategic calculus of Palestinian groups is complex and cannot be treated as time invariant. Our results suggest that factors such as the degree of public support, inter-group competition, the anticipation of countermeasures and non-trivial non-violent payoffs have an observable effect on the strategic behaviour of the Palestinian groups, and that structural relationships are often far from constant over time. </jats:p

Benzene at 1GHz. Magnetic field-induced fine structure

International audienceThe deuterium NMR spectrum of benzene-d(6) in a high field spectrometer (1 GHz protons) exhibits a magnetic field-induced deuterium quadrupolar splitting Delta v. The magnitude of Delta v observed for the central resonance is smaller than that observed for the C-13 satellite doublets Delta v'. This difference, Delta(Delta v) Delta v' - Delta v, is due to unresolved fine structure contributions to the respective resonances. We determine the origins of and simulate this difference, and report pulse sequences that exploit the connectivity of the peaks in the C-13 and H-2 spectra to determine the relative signs of the indirect coupling, J(CD), and Delta v. The positive sign found for Delta v is consonant with the magnetic field biasing of an isolated benzene molecule-the magnetic energy of the aromatic ring is lowest for configurations where the C-6 axis is normal to the field. In the neat liquid the magnitude of Delta v is decreased by the pair correlations in this prototypical molecular liquid

Age-related changes in gait biomechanics and their impact on the metabolic cost of walking: Report from a National Institute on Aging workshop

Changes in old age that contribute to the complex issue of an increased metabolic cost of walking (mass-specific energy cost per unit distance traveled) in older adults appear to center at least in part on changes in gait biomechanics. However, age-related changes in energy metabolism, neuromuscular function and connective tissue properties also likely contribute to this problem, of which the consequences are poor mobility and increased risk of inactivity-related disease and disability. The U.S. National Institute on Aging convened a workshop in September 2021 with an interdisciplinary group of scientists to address the gaps in research related to the mechanisms and consequences of changes in mobility in old age. The goal of the workshop was to identify promising ways to move the field forward toward improving gait performance, decreasing energy cost, and enhancing mobility for older adults. This report summarizes the workshop and brings multidisciplinary insight into the known and potential causes and consequences of age-related changes in gait biomechanics. We highlight how gait mechanics and energy cost change with aging, the potential neuromuscular mechanisms and role of connective tissue in these changes, and cutting-edge interventions and technologies that may be used to measure and improve gait and mobility in older adults. Key gaps in the literature that warrant targeted research in the future are identified and discussed

Characteristics of the nuclear (18S, 5.8S, 28S and 5S) and mitochondrial (12S and 16S) rRNA genes of Apis mellifera (Insecta: Hymenoptera): structure, organization, and retrotransposable elements

As an accompanying manuscript to the release of the honey bee genome, we report the entire sequence of the nuclear (18S, 5.8S, 28S and 5S) and mitochondrial (12S and 16S) ribosomal RNA (rRNA)-encoding gene sequences (rDNA) and related internally and externally transcribed spacer regions of Apis mellifera (Insecta: Hymenoptera: Apocrita). Additionally, we predict secondary structures for the mature rRNA molecules based on comparative sequence analyses with other arthropod taxa and reference to recently published crystal structures of the ribosome. In general, the structures of honey bee rRNAs are in agreement with previously predicted rRNA models from other arthropods in core regions of the rRNA, with little additional expansion in non-conserved regions. Our multiple sequence alignments are made available on several public databases and provide a preliminary establishment of a global structural model of all rRNAs from the insects. Additionally, we provide conserved stretches of sequences flanking the rDNA cistrons that comprise the externally transcribed spacer regions (ETS) and part of the intergenic spacer region (IGS), including several repetitive motifs. Finally, we report the occurrence of retrotransposition in the nuclear large subunit rDNA, as R2 elements are present in the usual insertion points found in other arthropods. Interestingly, functional R1 elements usually present in the genomes of insects were not detected in the honey bee rRNA genes. The reverse transcriptase products of the R2 elements are deduced from their putative open reading frames and structurally aligned with those from another hymenopteran insect, the jewel wasp Nasonia (Pteromalidae). Stretches of conserved amino acids shared between Apis and Nasonia are illustrated and serve as potential sites for primer design, as target amplicons within these R2 elements may serve as novel phylogenetic markers for Hymenoptera. Given the impending completion of the sequencing of the Nasonia genome, we expect our report eventually to shed light on the evolution of the hymenopteran genome within higher insects, particularly regarding the relative maintenance of conserved rDNA genes, related variable spacer regions and retrotransposable elements