Superconducting Properties of MgCNi3 Films

We report the magnetotransport properties of thin polycrystalline films of the recently discovered non-oxide perovskite superconductor MgCNi3. CNi3 precursor films were deposited onto sapphire substrates and subsequently exposed to Mg vapor at 700 C. We report transition temperatures (Tc) and critical field values (Hc2) of MgCNi3 films ranging in thickness from 7.5 nm to 100 nm. Films thicker than ~40 nm have a Tc ~ 8 K, and an upper critical field Hc2 ~ 14 T, which are both comparable to that of polycrystalline powders. Hall measurements in the normal state give a carrier density, n =-4.2 x 10^22 cm^-3, that is approximately 4 times that reported for bulk samples.Comment: submitted to PR

The Application of Microscopy and Other Imaging Techniques to the Study of Disease in the Fetus.

The application of both classical and advanced microscopy to the exploration of abnormal, human, fetal development (birth defects) and to other forms of human, fetal disease has generated a wealth of information, often documented by dramatic images. We have studied, at varying levels of inquiry (simple inspection to molecular analysis), some 10,000 normal and abnormal specimens. For presentation purposes, we first demonstrate the use of imaging in explorations of the fetal habitat (the gestational sac). Our studies reveal a variety of fetal surface encounter lesions (skin-to-amnion). Many of these lesions in the past have been erroneously interpreted. These include fetal amputations, strangulations, and also the reimplantation of amputated parts to ectopic sites. We have also explored, by various imaging techniques, developmental abnormalities within a variety of fetal organs.</jats:p

Are models too simple? Arguments for increased parameterization

The idea that models should be as simple as possible is often accepted without question. However, too much simplification and parsimony may degrade a model's utility. Models are often constructed to make predictions; yet, they are commonly parameterized with a focus on calibration, regardless of whether (1) the calibration data can constrain simulated predictions or (2) the number and type of calibration parameters are commensurate with the hydraulic property details on which key predictions may depend. Parameterization estimated through the calibration process is commonly limited by the necessity that the number of calibration parameters be smaller than the number of observations. This limitation largely stems from historical restrictions in calibration and computing capability; we argue here that better methods and computing capabilities are now available and should become more widely used. To make this case, two approaches to model calibration are contrasted: (1) a traditional approach based on a small number of homogeneous parameter zones defined by the modeler a priori and (2) regularized inversion, which includes many more parameters than the traditional approach. We discuss some advantages of regularized inversion, focusing on the increased insight that can be gained from calibration data. We present these issues using reasoning that we believe has a common sense appeal to modelers; knowledge of mathematics is not required to follow our arguments. We present equations in an Appendix, however, to illustrate the fundamental differences between traditional model calibration and a regularized inversion approach

Contract enforcement and the size of the informal economy

Limited enforcement, Informal sector, Economic development, O17, O10,