Superconductivity and Unusual Magnetic Features in Amorphous Carbon and in Other Unrelated Materials

Traces of superconductivity (SC) were observed in three different inhomogeneous sulfur-doped amorphous carbon (a-C) systems: (i) in old commercial powder, (ii) in fabricated (by pyrolytic decomposition of sucrose) powder, and (iii) in a-C thin films. (i) The commercial a-C powder contains 0.21 at% sulfur and reveals traces of two superconducting phases around T _C ?34 and T _C～65 K. (ii) The fabricated a-C powder is diamagnetic but not superconducting. However, mixtures of this powder with sulfur (a-CS) which were heated to 250 °C also show traces of SC up to T _C～42 K. (iii) Non-superconducting a-C thin films were grown by electron-beam induced deposition. SC at T _C～34 K emerged only after heat treatment with sulfur. It is proposed that the high SC states in a-CS (T _C～65 K at ambient pressure) and in H₃S materials (T _C = 203 K under >200 GPa) has the same origin. In both sulfur-containing systems, SC is induced by the interaction between electrons and the high frequencies of low mass atom (H or C) vibrations a-CS products obtained by heating commercial and fabricated a-C powders at 400 °C show unusual magnetic features: (a) pronounced irreversible peaks around 55–80 K which appear in the first zero-field-cooled (ZFC) runs only. This temperature range is close to the highest T _C observed. (b) These peaks are totally suppressed in the second ZFC sweeps measured a few minutes later. (c) The peaks reappear after 18 months. (d) Around the peak position, the field-cooled (FC) curves cross the ZFC plots (ZFC > FC). All these phenomena are intrinsic properties of the amorphous carbon materials and were not observed in crystalline graphite. The ZFC > FC state was also observed in chiral-based magnetic memory device and unexpectedly in the liver taken from a patient with mantle cell lymphoma. This peculiarity will be discussed.     

Inconsistent heuristics in theory and practice

In the field of heuristic search it is usually assumed that admissible heuristics are consistent, implying that consistency is a desirable attribute. The term “inconsistent heuristic” has, at times, been portrayed negatively, as something to be avoided. Part of this is historical: early research discovered that inconsistency can lead to poor performance for A^? (nodes might be re-expanded many times). However, the issue has never been fully investigated, and was not re-considered after the invention of IDA^?.This paper shows that many of the preconceived notions about inconsistent heuristics are outdated. The worst-case exponential time of inconsistent heuristics is shown to only occur on contrived graphs with edge weights that are exponential in the size of the graph. Furthermore, the paper shows that rather than being something to be avoided, inconsistent heuristics often add a diversity of heuristic values into a search which can lead to a reduction in the number of node expansions. Inconsistent heuristics are easy to create, contrary to the common perception in the AI literature. To demonstrate this, a number of methods for achieving effective inconsistent heuristics are presented.Pathmax is a way of propagating inconsistent heuristic values in the search from parent to children. This technique is generalized into bidirectional pathmax (BPMX) which propagates values from a parent to a child node, and vice versa. BPMX can be integrated into IDA^? and A^?. When inconsistent heuristics are used with BPMX, experimental results show a large reduction in the search effort required by IDA^?. Positive results are also presented for A^? searches.     

Dielectric Properties of Na<Subscript>0.7</Subscript>CoO<Subscript>2</Subscript> and of the Superconducting Na<Subscript>0.3</Subscript>CoO<Subscript>2</Subscript>·1.3H<Subscript>2</Subscript>O

We present dielectric properties of ceramic anhydrous Na_0.7CoO₂ and the superconducting Na_0.3CoO₂·1.3H₂O materials. The presence of water which induces superconductivity also may increase the dielectric constant (ε) of the hydrated material. This is consistent with the predicted relationship between the highε and the enhancement ofT _c in highT _c superconductors. The anhydrous sample is porous and the transport is due to some percolation via the pores. The porosity is much higher for the hydrated material and the transport is ionic inside bulk water.     

Unusual Magnetic Properties and Superconductivity in Sulfur-Doped Amorphous Carbon Powder

An amorphous carbon (a-C) powder obtained by decomposition of sucrose was mixed with sulfur and synthesized at 400 ^°C. Magnetic measurements reveal that the products obtained are inhomogeneous. Some parts show traces of superconductivity at T _C=17?and 42?K. Other parts show unusual magnetic features. (i)?Pronounced irreversible peaks around 50?K appear in the first zero-field-cooled (ZFC) sweep only. (ii) Unexpectedly, these peaks are totally suppressed in the second ZFC runs performed a few minutes later. Around the peak position, the field-cooled (FC) curves cross the ZFC plots, such that ZFC>FC. The two peculiar magnetic observations are connected to each other and are also ascribed to the a-C powder taken from commercial sources. The possibility that impurities cause these magnetic phenomena is excluded.     

M?ssbauer Spectroscopy Determination of Iron Foreign Phases in?the Superconducting Systems; RAsFeO1?x, RAsFeO1?xFx, and?Sr1?xKxFe2As2

The recently discovered superconducting—spin density wave materials, containing Fe and As, have raised huge interest. However, most materials prepared to date, suffer from a varying degree of content of foreign Fe–As phases, Fe₂As, FeAs₂, and FeAs, which can lead to wrong conclusions concerning the properties of these materials. We show here that M?ssbauer spectroscopy is able to determine quite easily the relative content of the foreign phases. This procedure is demonstrated by a study of seven samples of superconducting or spin density wave materials, prepared in three different laboratories.      

Child custody resolution: A study of social science involvement and impact.

To explore the use of mental health professional expertise in the legal system, legal professionals' sources of social science information, and the legal profession's perspectives on the appropriate roles of mental health professionals in the process, we solicited information from attorneys and judges on (a) the extent to which they actively seek the involvement of mental health professionals in child custody cases, (b) the factors that influence such involvement, and (c) the degree to which these attitudes and practices are influenced by social science data or theory. Among the most striking features of these results was the report by the overwhelming majority of legal professionals that they did not consider either social science data or mental health professionals' involvement or recommendations in child custody cases as critical to their practice of family law. Specifically, mental health participation was rarely solicited, and when it was, this decision rested primarily on the paradigmatic regularities of the legal system or practical needs of the case rather than on a view that such involvement was central to the client's or child's mental health. The implications of these findings for collaboration between the mental health and legal disciplines in the area of family policy are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)