A thermalized ion explosion model for high energy sputtering and track registration

A velocity spectrum of neutral sputtered particles as well as a low resolution mass spectrum of sputtered molecular ions was measured for 4.74 MeV F-19(+2) incident of UF4. The velocity spectrum is dramatically different from spectra taken with low energy (keV) bombarding ions, and is shown to be consistent with a hot plasma of atoms in thermal equilibrium inside the target. A thermalized ion explosion model is proposed for high energy sputtering which is expected to describe track formation in dielectric materials. The model is shown to be consistent with the observed total sputtering yield and the dependence of the yield on the primary ionization rate of the incident ion

Entry corridor definition and SM/RCS deorbit requirements for Apollo block 1 earth orbit missions. Project Apollo

Entry corridor definition and SM reaction control system for Apollo Block 1 earth orbit mission

Breaking a one-dimensional chain: fracture in 1 + 1 dimensions

The breaking rate of an atomic chain stretched at zero temperature by a constant force can be calculated in a quasiclassical approximation by finding the localized solutions ("bounces") of the equations of classical dynamics in imaginary time. We show that this theory is related to the critical cracks of stressed solids, because the world lines of the atoms in the chain form a two-dimensional crystal, and the bounce is a crack configuration in (unstable) mechanical equilibrium. Thus the tunneling time, Action, and breaking rate in the limit of small forces are determined by the classical results of Griffith. For the limit of large forces we give an exact bounce solution that describes the quantum fracture and classical crack close to the limit of mechanical stability. This limit can be viewed as a critical phenomenon for which we establish a Levanyuk-Ginzburg criterion of weakness of fluctuations, and propose a scaling argument for the critical regime. The post-tunneling dynamics is understood by the analytic continuation of the bounce solutions to real time.Comment: 15 pages, 5 figure

On the Interface Between LENS® Deposited Stainless Steel 304L Repair Geometry and Cast or Machined Components

Laser Engineered Net Shaping™ (LENS®) is being evaluated for use as a metal component repair/modification process. A component of the evaluation is to better understand the characteristics of the interface between LENS deposited material and the substrate on which it is deposited. A processing and metallurgical evaluation was made on LENS processed material fabricated for component qualification tests. A process parameter evaluation was used to determine optimum build parameters and these parameters were used in the fabrication of tensile test specimens to study the characteristics of the interface between LENS deposited material and several types of substrates. Analyses of the interface included mechanical properties, microstructure, and metallurgical integrity. Test samples were determined for a variety of geometric configurations associated with interfaces between LENS deposited material and both wrought base material or previously deposited LENS material. Thirteen different interface configurations were fabricated for evaluation representing a spectrum of deposition conditions from complete part build, to hybrid substrate-LENS builds, to repair builds for damaged or re-designed housings. Good mechanical properties and full density were observed for all configurations. When tested to failure, fracture occurred by ductile microvoid coalescence. The repair and hybrid interfaces showed the same metallurgical integrity as, and had properties similar to, monolithic LENS deposits.Mechanical Engineerin

Scattering in an environment

The cross section of elastic electron-proton scattering taking place in an electron gas is calculated within the Closed Time Path method. It is found to be the sum of two terms, one being the expression in the vacuum except that it involves dressing due to the electron gas. The other term is due to the scattering particles-electron gas entanglement. This term dominates the usual one when the exchange energy is in the vicinity of the Fermi energy. Furthermore it makes the trajectories of the colliding particles more consistent and the collision more irreversible, rendering the scattering more classical in this regime.Comment: final version to appear in Phys. Rev.

From meadows to milk to mucosa – adaptation of Streptococcus and Lactococcus species to their nutritional environments

Lactic acid bacteria (LAB) are indigenous to food-related habitats as well as associated with the mucosal surfaces of animals. The LAB family Streptococcaceae consists of the genera Lactococcus and Streptococcus. Members of the family include the industrially important species Lactococcus lactis, which has a long history safe use in the fermentative food industry, and the disease-causing streptococci Streptococcus pneumoniae and Streptococcus pyogenes. The central metabolic pathways of the Streptococcaceae family have been extensively studied because of their relevance in the industrial use of some species, as well as their influence on virulence of others. Recent developments in high-throughput proteomic and DNA-microarray techniques, in in vivo NMR studies, and importantly in whole-genome sequencing have resulted in new insights into the metabolism of the Streptococcaceae family. The development of cost-effective high-throughput sequencing has resulted in the publication of numerous whole-genome sequences of lactococcal and streptococcal species. Comparative genomic analysis of these closely related but environmentally diverse species provides insight into the evolution of this family of LAB and shows that the relatively small genomes of members of the Streptococcaceae family have been largely shaped by the nutritionally rich environments they inhabit.

Estimation of intrafamilial DNA contamination in family trio genome sequencing using deviation from Mendelian inheritance

With the increasing number of sequencing projects involving families, quality control tools optimized for family genome sequencing are needed. However, accurately quantifying contamination in a DNA mixture is particularly difficult when genetically related family members are the sources. We developed TrioMix, a maximum likelihood estimation (MLE) framework based on Mendel\u27s law of inheritance, to quantify DNA mixture between family members in genome sequencing data of parent-offspring trios. TrioMix can accurately deconvolute any intrafamilial DNA contamination, including parent-offspring, sibling-sibling, parent-parent, and even multiple familial sources. In addition, TrioMix can be applied to detect genomic abnormalities that deviate from Mendelian inheritance patterns, such as uniparental disomy (UPD) and chimerism. A genome-wide depth and variant allele frequency plot generated by TrioMix facilitates tracing the origin of Mendelian inheritance deviations. We showed that TrioMix could accurately deconvolute genomes in both simulated and real data sets

Fly-by-light flight control system technology development plan

The results of a four-month, phased effort to develop a Fly-by-Light Technology Development Plan are documented. The technical shortfalls for each phase were identified and a development plan to bridge the technical gap was developed. The production configuration was defined for a 757-type airplane, but it is suggested that the demonstration flight be conducted on the NASA Transport Systems Research Vehicle. The modifications required and verification and validation issues are delineated in this report. A detailed schedule for the phased introduction of fly-by-light system components has been generated. It is concluded that a fiber-optics program would contribute significantly toward developing the required state of readiness that will make a fly-by-light control system not only cost effective but reliable without mitigating the weight and high-energy radio frequency related benefits

A case of acute myeloid leukemia with promyelocytic features characterized by expression of a novel RARG-CPSF6 fusion

Key Points Novel RARG-CPSF6 fusion in an AML case with promyelocytic features and no evidence of PML-RARA or X-RARA fusion. Gene fusions involving RARG can initiate AML with promyelocytic morphological features.</jats:p