Reducing Work Content in Early Stage Naval Ship Designs

Naval Postgraduate School Acquisition Research Progra

Reducing Work Content in Early Stage Naval Ship Designs

Naval Postgraduate School Acquisition Research Progra

Waning magmatic activity along the Southern Explorer Ridge revealed through fault restoration of rift topography

International audienceWe combine high-resolution bathymetry acquired using the Autonomous Underwater Vehicle ABE with digital seafloor imagery collected using the remotely operated vehicle ROPOS across the axial valley of the Southern Explorer Ridge (SER) to infer the recent volcanic and tectonic processes. The SER is an intermediate spreading ridge located in the northeast Pacific. It hosts the Magic Mountain hydrothermal vent. We reconstruct the unfaulted seafloor terrain at SER based on calculations of the vertical displacement field and fault parameters. The vertical changes between the initial and the restored topographies reflect the integrated effects of volcanism and tectonism on relief-forming processes over the last 11,000-14,000 years. The restored topography indicates that the axial morphology evolved from a smooth constructional dome >500 m in diameter, to a fault-bounded graben, ~500 m wide and 30-70 m deep. This evolution has been accompanied by changes in eruptive rate, with deposition of voluminous lobate and sheet flows when the SER had a domed morphology, and limited-extent low-effusion rate pillow eruptions during graben development. Most of the faults shaping the present axial valley postdate the construction of the dome. Our study supports a model of cyclic volcanism at the SER with periods of effusive eruptions flooding the axial rift, centered on the broad plateau at the summit of the ridge, followed by a decrease in eruptive activity and a subsequent dominance of tectonic processes, with minor low-effusion rate eruptions confined to the axial graben. The asymmetric shape of the axial graben supports an increasing role of extensional processes, with a component of simple shear in the spreading processes

Reply to Itin, Obukhov and Hehl paper "An Electric Charge has no Screw Sense - A Comment on the Twist-Free Formulation of Electrodynamics by da Rocha & Rodrigues"

In this note we briefly comment a paper by Itin, Obukhov and Hehl criticising our previous paper. We show that all remarks by our critics are ill conceived or irrelevant to our approach and moreover we provide some pertinent new comments to their critical paper, with the aim to clarify even more our view on the subject.Comment: This paper is a reply to arXiv:0911.5175 [physics.class-ph] which made some criticisms on our paper "Pair and Impar, Even and Odd Form Fields and Electromagnetism" arXiv:0811.1713 [math-ph] to appear in Annalen der Physik. A short version of our reply will also appear in Annalen de Physi

An update on the human and animal enteric pathogen Clostridium perfringens

Clostridium perfringens, a rapid-growing pathogen known to secrete an arsenal of >20 virulent toxins, has been associated with intestinal diseases in both animals and humans throughout the past century. Recent advances in genomic analysis and experimental systems make it timely to re-visit this clinically and veterinary important pathogen. This Review will summarise our understanding of the genomics and virulence-linked factors, including antimicrobial potentials and secreted toxins of this gut pathogen, and then its up-to-date clinical epidemiology and biological role in the pathogenesis of several important human and animal-associated intestinal diseases, including pre-term necrotising enterocolitis. Finally, we highlight some of the important unresolved questions in relation to C. perfringens-mediated infections, and implications for future research directions

Lactones and Flavonoids isolated from the Leaves of Globimetula braunii

The dried powdered leaves of Globimetula braunii (Engler) Van Tiegh were effectively extracted by the cold extraction method. Purification of the EtOAc-soluble and MeOH-soluble extracts successfully yielded two lactones namely (R)-6-[(S)-2-hydroxy-4-(4-hydroxyphenyl)butyl]–5,6-dihydropyran-2-one (dodoneine) 1 and (1R,5S,7S)-[2-(4-hydroxyphenyl)ethyl]-2,6-dioxabicyclo[3.3.1]-nonan-3-one (2), together with five flavonoids namely quercetin 3, (+)-catechin 4, quercitrin 5, rutin 6 and avicularin 7. Their structures were established by spectroscopic means, and the absolute configuration of compound 1 was confirmed by X-ray analysis

Higgs After the Discovery: A Status Report

Recently, the ATLAS and CMS collaborations have announced the discovery of a 125 GeV particle, commensurable with the Higgs boson. We analyze the 2011 and 2012 LHC and Tevatron Higgs data in the context of simplified new physics models, paying close attention to models which can enhance the diphoton rate and allow for a natural weak-scale theory. Combining the available LHC and Tevatron data in the ZZ* 4-lepton, WW* 2-lepton, diphoton, and b-bbar channels, we derive constraints on the effective low-energy theory of the Higgs boson. We map several simplified scenarios to the effective theory, capturing numerous new physics models such as supersymmetry, composite Higgs, dilaton. We further study models with extended Higgs sectors which can naturally enhance the diphoton rate. We find that the current Higgs data are consistent with the Standard Model Higgs boson and, consequently, the parameter space in all models which go beyond the Standard Model is highly constrained.Comment: 37 pages; v2: ATLAS dijet-tag diphoton channel added, dilaton and doublet-singlet bugs corrected, references added; v3: ATLAS WW channel included, comments and references adde

Growth and dislocation studies of β-HMX

Background: The defect structure of organic materials is important as it plays a major role in their crystal growth properties. It also can play a subcritical role in “hot-spot” detonation processes of energetics and one such energetic is cyclotetramethylene-tetranitramine, in the commonly used beta form (β-HMX). Results: The as-grown crystals grown by evaporation from acetone show prismatic, tabular and columnar habits, all with {011}, {110}, (010) and (101) faces. Etching on (010) surfaces revealed three different types of etch pits, two of which could be identified with either pure screw or pure edge dislocations, the third is shown to be an artifact of the twinning process that this material undergoes. Examination of the {011} and {110} surfaces show only one type of etch pit on each surface; however their natural asymmetry precludes the easy identification of their Burgers vector or dislocation type. Etching of cleaved {011} surfaces demonstrates that the etch pits can be associated with line dislocations. All dislocations appear randomly on the crystal surfaces and do not form alignments characteristic of mechanical deformation by dislocation slip. Conclusions: Crystals of β-HMX grown from acetone show good morphological agreement with that predicted by modelling, with three distinct crystal habits observed depending upon the supersaturation of the growth solution. Prismatic habit was favoured at low supersaturation, while tabular and columnar crystals were predominant at higher super saturations. The twin plane in β-HMX was identified as a (101) reflection plane. The low plasticity of β-HMX is shown by the lack of etch pit alignments corresponding to mechanically induced dislocation arrays. On untwinned {010} faces, two types of dislocations exist, pure edge dislocations with b = [010] and pure screw dislocations with b = [010]. On twinned (010) faces, a third dislocation type exists and it is proposed that these pits are associated with pure screw dislocations with b = [010]

ASSOCIAÇÃO ENTRE A PRESENÇA DE UM FATOR DE 38 kDa NO PLASMA SEMINAL E A INIBIÇÃO DA MOTILIDADE ESPERMÁTICA NO JUNDIÁ Rhamdia quelen

Fatores proteicos tem sido indentificados no plasma seminal de peixes e mamíferos e, em algumas situações, associados com indicadores de qualidade espermática. Entretanto, para o jundiá (Rhamdia quelen), tais fatores como aqueles com potenciais associações ainda não foram descritos. Os objetivos deste estudo foram de identificar alguns fatores proteicos presentes no plasma seminal do jundiá e avaliar suas associações com a motilidade espermática. Através de eletroforese do tipo SDS-PAGE foram identificadas 14 bandas proteicas com peso molecular entre 217.1 e 7.1 kDa.  A motilidade espermática foi avaliada em 21 machos. Quatro bandas proteicas (81.5; 60.4; 33.6 e 25.5 kDa) foram detectadas em todas as amostras de plasma seminal analisadas. Uma banda proteica com peso molecular de 38.3 kDa foi associada com a baixa motilidade espermática no jundiá (P< 0,01), uma vez que foi detectada em 91.4% das amostras com motilidade menor que 80%. Estes resultados sugerem que esta banda proteica seminal associada com a baixa motilidade espermática poderá ser considerada como um potencial marcador bioquímico de qualidade seminal. Palavras-chaveS: Motilidade espermática, plasma seminal, proteínas, Rhamdia quelen, SDS-PAGE