Image registration using Fermat transforms

Binary boundary maps are obtained by edge detection, then their relative translation is determined by conventional cross-correlation computed by the Fermat transform. Use of boundary maps emphasises edges and sharp discontinuities, while rejecting disturbances related to nonuniform illumination, thus avoiding the costly normalisation step. Use of integer arithmetic allows significant savings in computation     

Results of surgical resection in patients over the age of 70 years with non small-cell lung cancer

Calcium release from the sarcoplasmic reticulum (SR) depending on depolarization of the transverse tubular membrane (TTM) caused by rapid ionic replacement was measured in skeletal muscle triadic vesicles using a stopped-flow apparatus and Fura-2, a membrane-impermeable Ca2+ indicator. Calcium release was triggered by an increase in the magnitude of depolarization. This Ca2+ release was inhibited by ruthenium red, digoxin and dantrolene, and enhanced by caffeine. Thus, Ca2+ release was found to occur through the SR Ca2+ release channel via TTM depolarization and to be able to cause skeletal muscle contraction. Calcium release curves could be divided into two phases. In contrast to other previous studies, in the fast phase the amount of released Ca2+ increased with an increase in the magnitude of depolarization but the Ca2+ release rate did not; on the other hand, in the slow phase the Ca2+ release rate increased but the amount of Ca2+ did not. Furthermore, the Ca2+ release rate was controlled by the luminal Ca2+ concentration of the SR only in the fast phase. These independent dual kinetics of Ca2+ release were explained by the calsequestrin regulation model.     

Isolation and Characterization of Squamous Cell Carcinoma-Derived Stem-like Cells: Role in Tumor Formation

In human epidermis, keratinocyte stem cells (KSC) are characterized by high levels of β₁-integrin, resulting in the rapid adhesion to type IV collagen. Since epithelial tumors originate from KSC, we evaluated the features of rapidly adhering (RAD) keratinocytes derived from primary human squamous cell carcinoma of the skin (cSCC). RAD cells expressed higher levels of survivin, a KSC marker, as compared to non-rapidly adhering (NRAD) cells. Moreover, RAD cells proliferated to a greater extent and were more efficient in forming colonies than NRAD cells. RAD cells also migrated significantly better than NRAD cells. When seeded in a silicone chamber and grafted onto the back skin of NOD SCID mice, RAD cells formed tumors 2–4 fold bigger than those derived from NRAD cells. In tumors derived from RAD cells, the mitotic index was significantly higher than in those derived from NRAD cells, while Ki-67 and survivin expression were more pronounced in RAD tumors. This study suggests that SCC RAD stem cells play a critical role in the formation and development of epithelial tumors.     

Evaluating differences between measured personal exposures to volatile organic compounds and concentrations in outdoor and indoor air

Accurate estimation of human exposures to volatile organic compounds (VOCs) is a key element of strategies designed to protect public health from the adverse effects of hazardous air pollutants. The focus here is on examining the capability of three different exposure metrics (outdoor community concentrations, indoor residential concentrations, and a simple time-weighted model) to estimate observed personal exposures to 14 VOCs. The analysis is based on 2-day average concentrations of individual VOCs measured concurrently in outdoor (O) air in three urban neighborhoods, indoor (I) air in participant's residences, and personal (P) air near the breathing zone of 71 healthy, nonsmoking adults. A median of four matched P-I-O samples was collected for each study participant in Minneapolis/St. Paul over three seasons (spring, summer, and fall) in 1999 using charcoal-based passive air samplers (3M model 3500 organic vapor monitors). Results show a clear pattern for the 14 VOCs, with P > I > O concentrations. Intra-individual variability typically spanned at least an order of magnitude, and inter-individual variability spanned 2 or more orders of magnitude for each of the 14 VOCs. Although both O and I concentrations generally underestimated personal exposures, I concentrations provided a substantially better estimate of measured P concentrations. Mean squared error (MSE) as well as correlation measures were used to assess estimator performance at the subject-specific level, and hierarchical, mixed effects models were used to estimate the bias and variance components of MSE by tertile of personal exposure. Bias and variance both tended to increase in the upper third of the P exposure distribution for O versus P and I versus P. A simple time-weighted model incorporating measured concentrations in both outdoor community air and indoor residential air provided no improvement over I concentration alone for the estimation of P exposure.     

Use of polarimetric lidar for the study of oriented ice plates in clouds

A polarization lidar operating at 532 nm was converted into an automatic, polarimetric lidar capable of measuring the entire Stokes vector of backscattered light and its derived quantities. Among these quantities, circular and linear depolarizations were studied as tools for investigating the presence of anisotropic scattering media. Isotropic scatterers show a simple relationship between linear and circular depolarization, a relation that we confirm theoretically and experimentally. Deviations from this relation, which are possible in the presence of anisotropic scatterers such as horizontally oriented ice plates when they are observed with a slant lidar, were studied both numerically and experimentally.     

Controlling the Functional Properties of Oligothiophene Crystalline Nano/Microfibers via Tailoring of the Self‐Assembling Molecular Precursors

Oligothiophenes are π‐conjugated semiconducting and fluorescent molecules whose self‐assembly properties are widely investigated for application in organic electronics, optoelectronics, biophotonics, and sensing. Here an approach to the preparation of crystalline oligothiophene nano/microfibers is reported based on the use of a “sulfur overrich” quaterthiophene building block, ? T4S4 ? , containing in its covalent network all the information needed to promote the directional, π–π stacking‐driven, self‐assembly of Y‐T4S4‐Y oligomers into fibers with hierarchical supramolecular arrangement from nano‐ to microscale. It is shown that when Y varies from unsubstituted thiophene to thiophene substituted with electron‐withdrawing groups, a wide redistribution of the molecular electronic charge takes place without substantially affecting the aggregation modalities of the oligomer. In this way, a structurally comparable series of fibers is obtained having progressively varying optical properties, redox potentials, photoconductivity, and type of prevailing charge carriers (from p‐ to n‐type). With the aid of density functional theory (DFT) calculations, combined with powder X‐ray diffraction data, a model accounting for the growth of the fibers from molecular to nano‐ and microscale is proposed.     

Surface electrostatic potentials in carbon nanotubes and graphene membranes investigated with electron holography

We used low-voltage transmission electron holography to probe surface electrostatic potentials in graphene membranes and carbon nanotubes, as the number of graphenes varies. Further, we measured the phase shift induced by an individual graphene, and mapped the phase shift variation throughout a whole few-graphene-crystal as a function of the local number of layers. We found a size/surface effect as the ratio between the surface and the total number of atoms increases for an individual nanotube or graphene membrane. This surface phase term can be related to a fine electrostatic potentials redistributions occurring at the outer layers in carbon nanotubes and graphene membranes.     

Parallel algorithms for the iterative solution of sparse least-squares problems

In this paper, we are concerned with a generalized Gauss-Seidel approach to sparse linear least-squares problems. Two algorithms, related to those given by Schechter (1959), for the solution of linear systems are presented and their parallel implementation is discussed. In these procedures, which can be viewed as an alternative ordering of the variables in the SOR methods, the variables are divided into nondisjoint groups. Numerical results, obtained on CRAY X-MP/48, are presented and discussed.