Cold cathode ionization gage has rigid metal housing

Cold cathode ionization gage in a stainless steel housing accurately measures high pressures. The penning effect is used with a high voltage discharge in the presence of a magnetic field for an ion current proportional to the gas pressure in the gage

Lunar lander mass spectrometer Final report

Sputter ion source for lunar lander mass spectromete

Development and fabrication of bismaleimide-graphite composites

The successful fabrication of high temperature resistant composites depends mainly on the processability of the resin binder matrix. For two new bismaleimide type resins the processing of graphite fabric prepregs to composites is described. One resin coded M 751 has to be processed from N-Methylpyrrolidone, the other resin evaluated is a so-called hot melt solvent-less system. Commercial T300/3000 Graphite fabrics were used as reinforcement. The M 751 - Resin is a press grade material and laminates are therefore moulded in high pressure conditions (400 N/sq cm). The solvent-less resin system H 795 is an autoclave grade material and can be cured at 40 N/sq cm. The cure cycles for both the press grade and the autoclave grade material (Fiberite W 143 fabric prepregs) are provided and the mechanical properties of laminates at low (23 C) and high (232 C) temperatures were measured. For comparison, the neat resin flexural properties are also presented. The water absorption for the neat resins and the graphite fabric laminates after a 1000 hour period was evaluated

Can We Study Titin Properties in Passive Myofibrils?

Titin is a giant molecular spring in skeletal and cardiac muscles. It has a variety of important passive, structural, sensing and force-regulatory functions, and thus has been investigated widely (Granzier & Labeit, 2007). Studying the mechanical properties of isolated titin has been difficult because of the enormous size and great instability of this protein. However, the passive properties in single myofibrils are almost exclusively explained by titin, and thus we asked the question if we can study titin properties in intact, passive myofibrils (Bartoo et al., 1997). Single myofibrils were isolated in a standard way (Leonard & Herzog, 2010) and three consecutive stretches of 1.0-3.5μm/sarcomere magnitude were performed at a nominal stretch speed of 0.1 sarcomere length/sarcomere/s. Sarcomere length were measured using a high resolution photo diode array and forces were measured using micro-electronically machined silicon nitrate levers. Single myofibrils frequently showed a distinct change in stiffness upon stretch at sarcomere length of approximately 3.6-3.8μm, they showed a decrease in loading energy with repeat stretch cycles and their efficiency decreased for all loading cycles with increasing stretch magnitude. These properties are in agreement with results observed in single titin preparations (Kellermayer et al., 1997). Therefore, we conclude that titin properties can be studied using single myofibrils. This has at least two significant advantages over tests with isolated titin proteins: (i) testing is technically much easier and (ii) titin is arranged in its intact structural arrangement. In the future, we would like to study titin properties in calcium activated myofibrils in which active (actin-myosin based cross-bridges forces) are eliminated either by chemical inhibition or by deletion of regulatory proteins on actin, as we have done before (Joumaa et al., 2008)

Mass spectrometer analysis of solid materials with the ion-microprobe sputter source

Sputter ion source mass spectrometer for analysis of solid material

Study of Giant Pairing Vibrations with neutron-rich nuclei

We investigate the possible signature of the presence of giant pairing states at excitation energy of about 10 MeV via two-particle transfer reactions induced by neutron-rich weakly-bound projectiles. Performing particle-particle RPA calculations on $^{208}$Pb and BCS+RPA calculations on $^{116}$Sn, we obtain the pairing strength distribution for two particles addition and removal modes. Estimates of two-particle transfer cross sections can be obtained in the framework of the 'macroscopic model'. The weak-binding nature of the projectile kinematically favours transitions to high-lying states. In the case of (~^6He, \~^4He) reaction we predict a population of the Giant Pairing Vibration with cross sections of the order of a millibarn, dominating over the mismatched transition to the ground state.Comment: Talk presented in occasion of the VII School-Semina r on Heavy Ion Physics hosted by the Flerov Laboratory (FLNR/JINR) Dubna, Russia from May 27 to June 2, 200

Long-term periarticular bone adaptation in a feline knee injury model for post-traumatic experimental osteoarthritis

SummaryObjectivesThis study investigates the long-term changes of the periarticular bone, including cancellous bone and the subchondral plate, in an anterior cruciate ligament (ACL)-transected cat for post-traumatic osteoarthritis (OA). These periarticular bone changes are related to the health of all knee tissues including articular cartilage degeneration and may be a key component of osteoarthritic development.MethodsThirteen cats (mean mass 4.9±1.9kg) were divided into three experimental groups: (1) normal controls, (2) 16 week, and (3) 5 year post unilateral ACL-transection (ACLT). Micro-computed tomography was used to scan the three-dimensional (3D) bone architecture of the proximal tibia, and analysis was performed on the subchondral plate and cancellous bone in the epiphyseal and metaphyseal regions of each bone.ResultsA decrease in cancellous bone mass (BV/TV) and subchondral plate thickness (Ct.Th) was observed 16 week post-ACLT, and the trend was statistically significant for the long-term animals (>5 year post-ACLT: BV/TV decreased 16.8%, P<0.003; Ct.Th decreased 36.8%, P<0.03). A decrease in bone mass was also observed as a function of animal age by comparing the young and aged normal control animals, however ACLT intensified those changes, particularly Ct.Th (P<0.009) and anisotropy (P<0.045). It was speculated that decreased internal joint loading despite normal kinematics may play an important role in the long-term reduction of cancellous bone volume and subchondral plate thinning.ConclusionsThe periarticular bone changes measured in this study were concurrent with articular cartilage degeneration, and suggest that bone may be a contributing factor in the aetiology of post-traumatic OA development

Effects of Force Enhancement and Force Depression on Postactivation Potentiation in the Human Adductor Pollicis

Force enhancement and force depression following active stretch and shortening are commonly observed muscle properties. However the mechanisms underlying these properties are not fully understood. Increased or decreased muscle potentiation (that is, the amount of phosphorylation of the myosin light chains) might contribute to force enhancement and force depression but has never been examined. In this study, we examined the effect of active stretch and shortening on potentiation of the in vivo human adductor pollicis muscle to determine whether the phosphorylation that causes muscle potentiation is a viable contributor to force enhancement and depression. Potentiation was assessed with twitch contractions and the contribution of potentiation to force enhancement/depression was assessed by comparing the force of isometric contractions prior to and following muscle potentiation. Subjects were given twitches before and after maximum voluntary isometric contractions at a thumb adduction angle of 30° and 0°, and these twitches were compared to twitches given before and after an active stretch from 0° to 30° (n=15) and an active shortening (n=12) from 30° to 0°. Stretch and shortening contractions were then followed 10s later by an isometric contraction at the finishing position to observe any effects of changed potentiation on maximal voluntary isometric contractions. Potentiation was increased significantly (17%) after active muscle stretching but remained unchanged following active muscle shortening. The increased potentiation following active muscle stretching did not affect isometric forces. We conclude from these results that active muscle stretching increases the amount of muscle potentiation, but does not contribute to the force enhancement observed following active muscle stretch. We speculate that the stretch-induced increase in muscle potentiation is a mechanism for saving energy during sub- maximal and maximal muscular contractions

N=1 gauge superpotentials from supergravity

We review the supergravity derivation of some non-perturbatively generated effective superpotentials for N=1 gauge theories. Specifically, we derive the Veneziano-Yankielowicz superpotential for pure N=1 Super Yang-Mills theory from the warped deformed conifold solution, and the Affleck-Dine-Seiberg superpotential for N=1 SQCD from a solution describing fractional D3-branes on a C^3 / Z_2 x Z_2 orbifold.Comment: LaTeX, iopart class, 8 pages, 3 figures. Contribution to the proceedings of the workshop of the RTN Network "The quantum structure of space-time and the geometric nature of fundamental interactions", Copenhagen, September 2003; v2: published version with minor clarification