A computer program for the calculation of thermal stratification and self-pressurization in a liquid hydrogen tank

An analysis and computer program are described for calculating the thermal stratification and the associated self-pressurization of a closed liquid hydrogen tank. FORTRAN-IV language is used and runs were made on IBM 360/65 and CDC 3600 computers. Comparisons are made between the program calculations and test results from both ground and orbital coast tests of a Centaur space vehicle

Acidosis Is a Key Regulator of Osteoblast Ecto-Nucleotidase Pyrophosphatase/Phosphodiesterase 1 (NPP1) Expression and Activity

Previous work has shown that acidosis prevents bone nodule formation by osteoblasts in vitro by inhibiting mineralisation of the collagenous matrix. The ratio of phosphate (Pi) to pyrophosphate (PPi) in the bone microenvironment is a fundamental regulator of bone mineralisation. Both Pi and PPi, a potent inhibitor of mineralisation, are generated from extracellular nucleotides by the actions of ecto‐nucleotidases. This study investigated the expression and activity of ecto‐nucleotidases by osteoblasts under normal and acid conditions. We found that osteoblasts express mRNA for a number of ecto‐nucleotidases including NTPdase 1–6 (ecto‐nucleoside triphosphate diphosphohydrolase) and NPP1‐3 (ecto‐nucleotide pyrophosphatase/phosphodiesterase). The rank order of mRNA expression in differentiating rat osteoblasts (day 7) was Enpp1 > NTPdase 4 > NTPdase 6 > NTPdase 5 > alkaline phosphatase > ecto‐5‐nucleotidase > Enpp3 > NTPdase 1 > NTPdase 3 > Enpp2 > NTPdase 2. Acidosis (pH 6.9) upregulated NPP1 mRNA (2.8‐fold) and protein expression at all stages of osteoblast differentiation compared to physiological pH (pH 7.4); expression of other ecto‐nucleotidases was unaffected. Furthermore, total NPP activity was increased up to 53% in osteoblasts cultured in acid conditions (P < 0.001). Release of ATP, one of the key substrates for NPP1, from osteoblasts, was unaffected by acidosis. Further studies showed that mineralised bone formation by osteoblasts cultured from NPP1 knockout mice was increased compared with wildtypes (2.5‐fold, P < 0.001) and was partially resistant to the inhibitory effect of acidosis. These results indicate that increased NPP1 expression and activity might contribute to the decreased mineralisation observed when osteoblasts are exposed to acid conditions

Tibial fractures in the dog and cat: Options for management

[No abstract available

Book Review: \u3ci\u3eBiologie des Coleopteres Chrysomelides\u3c/i\u3e by Pierre Jolivetj

The main biological aspects of this economically important group of beetles, the Chrysomelidae, are summarized in this new work by the internationally known author, Dr. Pierre Jolivet. Around 37,000 species are now described and more remain to be named. The size and diversity of the family are less than those of the weevils (Curculionidae), but probably there will be a total of 40 to 50 thousand species once the canopy fauna is better known. For instance, we still know nothing about the biology and the host plants of the Madagascaran leaf beetles and surely many more species from that region await description

Book Review: \u3ci\u3eBiologie des Coleopteres Chrysomelides\u3c/i\u3e by Pierre Jolivetj

The main biological aspects of this economically important group of beetles, the Chrysomelidae, are summarized in this new work by the internationally known author, Dr. Pierre Jolivet. Around 37,000 species are now described and more remain to be named. The size and diversity of the family are less than those of the weevils (Curculionidae), but probably there will be a total of 40 to 50 thousand species once the canopy fauna is better known. For instance, we still know nothing about the biology and the host plants of the Madagascaran leaf beetles and surely many more species from that region await description

Activation of the P2Y2 receptor regulates bone cell function by enhancing ATP release

Bone cells constitutively release ATP into the extracellular environment where it acts locally via P2 receptors to regulate bone cell function. Whilst P2Y2 receptor stimulation regulates bone mineralisation, the functional effects of this receptor in osteoclasts remain unknown. This investigation used the P2Y2 receptor knockout (P2Y2R−/−) mouse model to investigate the role of this receptor in bone. MicroCT analysis of P2Y2R−/− mice demonstrated age-related increases in trabecular bone volume (≤48%), number (≤30%) and thickness (≤17%). In vitro P2Y2R−/− osteoblasts displayed a 3-fold increase in bone formation and alkaline phosphatase activity, whilst P2Y2R−/− osteoclasts exhibited a 65% reduction in resorptive activity. Serum cross-linked C-telopeptide levels (CTX, resorption marker) were also decreased (≤35%). The resorption defect in P2Y2R−/− osteoclasts was rescued by the addition of exogenous ATP, suggesting that an ATP deficit could be a key factor in the reduced function of these cells. In agreement, we found that basal ATP release was reduced up to 53% in P2Y2R−/− osteoclasts. The P2Y2 receptor agonists, UTP and 2-thioUTP, increased osteoclast activity and ATP release in wild-type but not in P2Y2R−/− cells. This indicates that the P2Y2 receptor may regulate osteoclast function indirectly by promoting ATP release. UTP and 2-thioUTP also stimulate ATP release from osteoblasts suggesting that the P2Y2 receptor exerts a similar function in these cells. Taken together, our findings are consistent with the notion that the primary action of P2Y2 receptor signalling in bone is to regulate extracellular ATP levels

Chemical equilibrium and stable stratification of a multi-component fluid: thermodynamics and application to neutron stars

A general thermodynamic argument shows that multi-component matter in full chemical equilibrium, with uniform entropy per baryon, is generally stably stratified. This is particularly relevant for neutron stars, in which the effects of entropy are negligible compared to those of the equilibrium composition gradient established by weak interactions. It can therefore be asserted that, regardless of the uncertainties in the equation of state of dense matter, neutron stars are stably stratified. This has important, previously discussed consequences for their oscillation modes, magnetic field evolution, and internal angular momentum transport.Comment: AASTeX, 8 pages, including 1 PS figure. Accepted for publication in The Astrophysical Journa

SN1987A - a Testing Ground for the KARMEN Anomaly

We show, that SN1987A can serve as an astrophysical laboratory for testing the viability of the assertion that a new massive neutral fermion is implied by the KARMEN data. We show that a wide range of the parameters characterizing the proposed particle is ruled out by the above constraints making this interpretation very unlikely.Comment: 12 pages, 1 eps figure embedded, to appear in Phys. Lett.

CSE style manual and requirements for publication in \u3ci\u3eInsecta Mundi\u3c/i\u3e

The CSE quarterly journal, Insecta Mundi, is among the very few journals that have no page charges. Even so, the Center for Systematic Entomology is entirely financed through dues, subscriptions, and donations of cash, property, and time. We have found it necessary to make certain requirements for publication in the journal. (See also information on front inside cover of the journal.