Computer simulation of high-frequency combustion instability and its supression

Program for simulation of gas motion illustrates the effects of some of the variables on the combustion chambers of liquid propellant rocket engines. The program is based on numerically integrating the laws of inviscid fluid dynamics by two-step Lax-Wendroff technique

Applications of Bayesian model selection to cosmological parameters

Bayesian model selection is a tool to decide whether the introduction of a new parameter is warranted by data. I argue that the usual sampling statistic significance tests for a null hypothesis can be misleading, since they do not take into account the information gained through the data, when updating the prior distribution to the posterior. On the contrary, Bayesian model selection offers a quantitative implementation of Occam's razor. I introduce the Savage-Dickey density ratio, a computationally quick method to determine the Bayes factor of two nested models and hence perform model selection. As an illustration, I consider three key parameters for our understanding of the cosmological concordance model. By using WMAP 3-year data complemented by other cosmological measurements, I show that a non-scale invariant spectral index of perturbations is favoured for any sensible choice of prior. It is also found that a flat Universe is favoured with odds of 29:1 over non--flat models, and that there is strong evidence against a CDM isocurvature component to the initial conditions which is totally (anti)correlated with the adiabatic mode (odds of about 2000:1), but that this is strongly dependent on the prior adopted. These results are contrasted with the analysis of WMAP 1-year data, which were not informative enough to allow a conclusion as to the status of the spectral index. In a companion paper, a new technique to forecast the Bayes factor of a future observation is presented.Comment: v2 to v3: minor changes, matches accepted version by MNRAS. v1 to v2: major revision. New results using WMAP 3-yr data, scale-invariant spectrum now disfavoured with moderate evidence. New benchmark test for the accuracy of the method. Bayes factor forecast methodology (PPOD, formerly called ExPO) expanded and now presented in a companion paper (astro-ph/0703063

Herbal Medicine : Consumers, Knowledge, and Self-disclosure in the Rural Elderly

The purpose of this study was fourfold: (1) to identify the knowledge level of elderly rural residents concerning the safety, efficacy, and quality of herbal medicine; (2) to determine how many elderly rural residents are using herbs; (3) to identify if herbal medicine users disclose their use to their healthcare provider; and ( 4) to determine if a relationship exists among elderly rural residents, demographic characteristics, knowledge level, likelihood of self-disclosure, and use of herbal medicine. This study was a descriptive correlational design. The sample was elderly males and females residing in southwestern Minnesota who were members of their local senior citizen center. The significance of this study was related to the fact that herbal medicine use in the United States has increased over the past ten years. The safety, efficacy, and quality of herbs are not well-known and the Food and Drug Administration does not regulate them. The elderly population is at greater risk for herbal medicine and drug interactions. Educational programs are needed to educate the elderly population about the safety, efficacy, and quality of herbal medicines

Ethical Considerations: Growth Hormone Treatment in Children with Idiopathic Short Stature

Being short is a natural diversity of the human race. In 2003, the Food and Drug Administration (FDA) approved the use of growth hormone (GH) for the treatment of idiopathic short stature (ISS) in children. Research has shown that GH therapy in children with ISS has a variable effect on increasing height. However, the literature has not shown the efficacy in improving psychosocial function to justify the costs and potential adverse effects. GH use in children with ISS is a subject of great ethical debate. Ethical implications including beneficence, nonmaleficence, autonomy, and justice are discussed. ISS requires thoughtful consideration by the patient, parents, and healthcare professionals. Well-designed long-term studies are needed to determine the benefits of such treatment

Josephson Effect in Pb/I/NbSe2 Scanning Tunneling Microscope Junctions

We have developed a method for the reproducible fabrication of superconducting scanning tunneling microscope (STM) tips. We use these tips to form superconductor/insulator/superconductor tunnel junctions with the STM tip as one of the electrodes. We show that such junctions exhibit fluctuation dominated Josephson effects, and describe how the Josephson product IcRn can be inferred from the junctions' tunneling characteristics in this regime. This is first demonstrated for tunneling into Pb films, and then applied in studies of single crystals of NbSe2. We find that in NbSe2, IcRn is lower than expected, which could be attributed to the interplay between superconductivity and the coexisting charge density wave in this material.Comment: 3 pages, 2 figures. Presented at the New3SC-4 meeting, San Diego, Jan. 16-21 200

How useful is consolidation of public sector entities' financial statements ?

Whether or not to consolidate financial statements is dealt with in IPSAS#6. This standard is by and large based on IAS#27. It deals with the criterion according to which an entity's financial statements should be considered and which consolidation technique should be used. However, it remains silent when it comes to exposing the reason why a public sector entity should consolidate its financial statements. The literature is almost as silent as IPSAS on this issue. Which means that there is a lack of both theoretical and empirical knowledge on this subject. This paper explores the usefulness of the consolidation of financial statements (CFS) for different categories of users. It aims at investigating for which purposes consolidation is most useful and whether enlarging the scope of the consolidate group serves these purposes. Five purposes are considered: information, decision- making, accountability, risk-assessment, statistics improvement. The paper also aims at investigating if some categories of users consider CFS more useful than others. The issue is essentially empirical. Therefore it is examined in light of the results of an in-person interviews. We surveyed 25members of parliament, officials, creditors, and consultants of the Swiss central government. The results show that consolidating FS is considered especially important and useful for risk- assessment, information and accountability and to a somewhat lesser extent for decision-making and statistics improvement. Extending the scope of CFS may improve the situation when it comes to statistics but it would only marginally make CFS more relevant for decision making. Consultants and, to a lesser extent, members of the finance ministry are those respondents who deem the scope enlargement to be the most useful

The isocurvature fraction after WMAP 3-year data

I revisit the question of the adiabaticity of initial conditions for cosmological perturbations in view of the 3-year WMAP data. I focus on the simplest alternative to pure adiabatic conditions, namely a superposition of the adiabatic mode and one of the 3 possible isocurvature modes, with the same spectral index as the adiabatic component. I discuss findings in terms of posterior bounds on the isocurvature fraction and Bayesian model selection. The Bayes factor (models likelihood ratio) and the effective Bayesian complexity are computed for several prior ranges for the isocurvature content. I find that the CDM isocurvature fraction is now constrained to be less than about 10%, while the fraction in either the neutrino entropy or velocity mode is below about 20%. Model comparison strongly disfavours mixed models that allow for isocurvature fractions larger than unity, while current data do not allow to distinguish between a purely adiabatic model and models with a moderate (ie, below about 10%) isocurvature contribution. The conclusion is that purely adiabatic conditions are strongly favoured from a model selection perspective. This is expected to apply in even stronger terms to more complicated superpositions of isocurvature contributions.Comment: Expanded discussion of degeneracies, updated references, no change to conclusions. Matches published versio