Stellar adiabatic mass loss model and applications

Roche-lobe overflow and common envelope evolution are very important in binary evolution, which is believed to be the main evolutionary channel to hot subdwarf stars. The details of these processes are difficult to model, but adiabatic expansion provides an excellent approximation to the structure of a donor star undergoing dynamical time scale mass transfer. We can use this model to study the responses of stars of various masses and evolutionary stages as potential donor stars, with the urgent goal of obtaining more accurate stability criteria for dynamical mass transfer in binary population synthesis studies. As examples, we describe here several models with the initial masses equal to 1 Msun and 10 Msun, and identify potential limitations to the use of our results for giant-branch stars.Comment: 7 pages, 5 figures,Accepted for publication in AP&SS, Special issue Hot Sub-dwarf Stars, in Han Z., Jeffery S., Podsiadlowski Ph. ed

On the Economies of Scale and Budget Allocations in Information Technology Services Provision

This study reexamines some fundamental questions in the network era of computing using the data after 1995 when firms have made significant investments in newer types of IT systems. Our findings suggest that firms realize some economies of scale in IT services as they grow in size. We also find that the personnel-hardware ratio is not independent of IT budget. Finally, we find that personnel-hardware ratio was declining during 1999-2003 period in response to changes in factor prices of hardware and personnel. We discuss implications of these results for academic research and for managerial practice

Exceptionally elevated triglyceride in severe lipemia retinalis

PURPOSE: To report a case of successful treatment for severe lipemia retinalis with extreme severe hypertriglyceridemia (sHTG). DESIGN: Observational case report. OBSERVATIONS: A 6-week-old infant with severe lipemia retinalis manifested diffuse creamy retinal vessels complicated with vulvar xanthomas. Extreme sHTG with 185-folds of the normal level was reported. Chromosome microarray and lipid gene sequencing confirmed a homozygous lipoprotein lipase gene coding mutation. RESULTS: Under strict adherence to a high medium-chain triglycerides formula and discontinuation of breast milk, the lipemia retinalis and vulval lesions resolved along with a stable plasma lipid level throughout the follow-up period of 6 months. CONCLUSION: Strict adherence to a low-fat diet without breast milk appears to be effective in treating infants with severe lipemia retinalis associated with exceptionally high triglycerides

Hadron Collider Signatures for New Interactions of Top and Bottom Quarks

One of the main goals for hadron colliders is the study of the properties of the third generation quarks. We study the signatures for new TeV resonances that couple to top or bottom quarks both at the Tevatron Run II and at the LHC. We find that in the simplest production processes of Drell-Yan type at the Tevatron, the signals are overwhelmed by QCD backgrounds. We also find that it is possible to study these resonances when they are produced in association with a pair of heavy quarks or in association with a single top at the LHC.In particular, with an integrated luminosity of 300 fb$^{-1}$ at the LHC, it is possible to probe resonance masses up to around 2 TeV.Comment: 24 pages, 15 figures, Minor corrections, version to appear in Phys. Rev.

Wormhole phase in the RST model

We show that the RST model describing the exactly soluble black hole model can have a dynamical wormhole solution along with an appropriate boundary condition. The necessary exotic matter which is usually negative energy density is remarkably produced by the quantization of the infalling matter fields. Then the asymptotic geometry in the past is two-dimensional anti-de Sitter(AdS$_2$), which implies the exotic matter is negative. As time goes on, the wormhole eventually evolves into the black hole and its Hawking radiation appears. The throat of the static RST wormhole is lower-bounded but in the presence of infalling matter it collapses to a black hole.Comment: v1. REVTeX3, 12 pages and 1 figure; v2. JHEP3, 10 pages and 1 figure, version published in JHE

Biosafety of RNA silencing and genome editing technologies in crop plants: Malaysian and Australian research perspectives

Research in agricultural biotechnology can produce novel solutions to address the ever growing demand for food, feed, renewable materials and renewable energy using increasingly limited resources. Yet research is expensive with long timelines before implementation can disseminate the benefits to society, so there is a need to maximise co-operation and communication between scientists, stakeholders and their governments, to optimise research, its development and the implementation of research outcomes, into mainstream applications. Recognising the impacts of regulations on biosafety, biosecurity and intellectual property policy on strategies for research, senior and early career researchers from two research intensive universities in Malaysia and Australia, held a workshop to identify and to deliberate over two key areas of technology that offer much promise for agriculture, namely RNA silencing and genome editing. A major focus of the workshop was the regulation of new breeding technologies, and how the regulations need to take into account these new technologies. Themes discussed were the need for harmonisation of international legal frameworks and careful use of terminology, standards and guidelines; and the need for good communication and consensus within and between groups of stakeholders and law-makers. This mini-review highlights the deliberations and recommendations from the workshop

Numerical Simulation of Temperature Field in Ultra-Narrow Arc Welding of Thick-Walled Steam Turbine Valve Body Material

The welding problems of large and thick plates are becoming more prominent as the application of large-scale and thick-plate metal structures grows. Due to the issue of excessive welding deformation between the 60mm thick steam turbine valve body and the pipe joint, a new process method is employed to connect. In this paper, the welding technology of flux strip confined arc ultra-narrow gap is proposed to carry out welding test on the ZG13Cr9Mo2Co1NiVNbNB cast steel test block of steam turbine valve body material with a thickness of 60 mm. The welding temperature field is measured by means of a K-type thermocouple and numerical simulation. The results show that the thermal cycle curve obtained by the homogeneous body heat source simulation is basically consistent with the thermal cycle curve measured during the experiment, and the simulation results of the molten pool morphology are also consistent with the actual macroscopic morphology of the weld

Numerical Simulation of Temperature Field in Ultra-Narrow Arc Welding of Thick-Walled Steam Turbine Valve Body Material

The welding problems of large and thick plates are becoming more prominent as the application of large-scale and thick-plate metal structures grows. Due to the issue of excessive welding deformation between the 60mm thick steam turbine valve body and the pipe joint, a new process method is employed to connect. In this paper, the welding technology of flux strip confined arc ultra-narrow gap is proposed to carry out welding test on the ZG13Cr9Mo2Co1NiVNbNB cast steel test block of steam turbine valve body material with a thickness of 60 mm. The welding temperature field is measured by means of a K-type thermocouple and numerical simulation. The results show that the thermal cycle curve obtained by the homogeneous body heat source simulation is basically consistent with the thermal cycle curve measured during the experiment, and the simulation results of the molten pool morphology are also consistent with the actual macroscopic morphology of the weld

What Precision Electroweak Physics Says About the SU(6)/Sp(6) Little Higgs

We study precision electroweak constraints on the close cousin of the Littlest Higgs, the SU(6)/Sp(6) model. We identify a near-oblique limit in which the heavy W' and B' decouple from the light fermions, and then calculate oblique corrections, including one-loop contributions from the extended top sector and the two Higgs doublets. We find regions of parameter space that give acceptably small precision electroweak corrections and only mild fine tuning in the Higgs potential, and also find that the mass of the lightest Higgs boson is relatively unconstrained by precision electroweak data. The fermions from the extended top sector can be as light as 1 TeV, and the W' can be as light as 1.8 TeV. We include an independent breaking scale for the B', which can still have a mass as low as a few hundred GeV.Comment: 52 pages, 16 figure

Production of Weak Bosons and Higgs Bosons at e-e- Colliders

We present calculations of cross sections for single $W^-$ and $Z$ production and $W^-W^-, W^-Z, W^-\gamma, ZZ$, and $W^+W^-$ pair production within the Standard Model at $e^-e^-$ linear colliders. We evaluate Standard-Model Higgs boson production in the channels $e^-e^- \to e^-e^- H$, $e^-\nu W^- H$, and $e^-e^- ZH$. We also illustrate the enhancements in the $W^-W^-$ cross section that would result from a strongly-interacting Higgs sector or from a $H^{--}$ resonance in a Higgs doublet + triplet model.Comment: Standard Latex, 19 pages of text. 11 postscript figures included; hardcopies by fax or mail available upon request. MAD/PH/77