CM-DiI and MCF-7 Breast Cancer Cell Responses to Chemotherapeutic Agents

CM-DiI is a lipophilic, red fluorescent dye used for staining and tracking the migration of cells. CM-DiI makes it possible to visualize cells in histological regions and can therefore be very useful for the tracking of cancer cell proliferation and metastasis in vivo. The ability to track and quantitate cancer cell proliferation in vivo is essential for cancer drug discovery. If CM-DiI labeled cancer cells respond to chemotherapy agents similar to unlabeled cancer cells, it facilitates screening of potential anti-cancer compounds using CM-DiI labeled cells in a xenotransplanted, transgenic zebrafish model (Danio rerio). To investigate whether CM-DiI labeling would affect cancer cells’ sensitivity when treated with established chemotherapeutic agents, the human breast cancer cell line MCF-7 was used. The chemotherapeutic agents used were doxorubicin, 4-hydroxytamoxifen, and paclitaxel. We hypothesized that CM-DiI would have no effect on the cells’ viability and sensitivity when treated with the chemotherapeutic drugs. Both labeled and unlabeled MCF-7 cells were seeded and after 24 hours each plate was treated with one of ten concentrations ranging from 0.05 µM to 1 mM of a chemotherapy compound. After incubating for 72 hours, cell viability was determined using a colorimetric MTS assay. Cell viability was not significantly different between labeled and unlabeled cells following exposure to doxorubicin and 4-hydroxytamoxifen. The results for paclitaxel, however, were inconclusive. These results provided evidence to support future aims wherein CM-DiI stained breast cancer cells will be injected into transparent zebrafish that possess green fluorescent protein labeled vasculature enabling the tracking of cells’ growth and migration while in the presence of potential new anti-cancer drugs

Exact trace formulae for a class of one-dimensional ray-splitting systems

Based on quantum graph theory we establish that the ray-splitting trace formula proposed by Couchman {\it et al.} (Phys. Rev. A {\bf 46}, 6193 (1992)) is exact for a class of one-dimensional ray-splitting systems. Important applications in combinatorics are suggested.Comment: 14 pages, 3 figure

Dynamic black-hole entropy

We consider two non-statistical definitions of entropy for dynamic (non-stationary) black holes in spherical symmetry. The first is analogous to the original Clausius definition of thermodynamic entropy: there is a first law containing an energy-supply term which equals surface gravity times a total differential. The second is Wald's Noether-charge method, adapted to dynamic black holes by using the Kodama flow. Both definitions give the same answer for Einstein gravity: one-quarter the area of the trapping horizon.Comment: 3 pages, revte

Emotional and non-emotional memories are suppressible under direct suppression instructions

Research on retrieval suppression has produced varying results concerning whether negatively valenced memories are more or less suppressible than neutral memories. This variability may arise if, across studies, participants adopt different approaches to memory control. Cognitive and neurobiological research points to two mechanisms that achieve retrieval suppression: thought-substitution and direct suppression (Benoit & Anderson, 2012; Bergström, de Fockert, & Richardson-Klavehn, 2009). Using the Think/No-think paradigm, this study examined whether participants can inhibit neutral and negatively valenced memories, using a uniform direct suppression strategy. Importantly, when strategy was controlled, negative and neutral items were comparably inhibited. Participants reported high compliance with direct suppression instructions, and success at controlling awareness predicted forgetting. These findings provide the first evidence that direct suppression can impair negatively valenced events, and suggest that variability in forgetting negative memories in prior studies is unlikely to arise from difficulty using direct suppression to control emotionally negative experiences

Using a thermal-based two source energy balance model with time-differencing to estimate surface energy fluxes with day-night MODIS observations

The Dual Temperature Difference (DTD) model, introduced by Norman et al. (2000), uses a two source energy balance modelling scheme driven by remotely sensed observations of diurnal changes in land surface temperature (LST) to estimate surface energy fluxes. By using a time-differential temperature measurement as input, the approach reduces model sensitivity to errors in absolute temperature retrieval. The original formulation of the DTD required an early morning LST observation (approximately 1 h after sunrise) when surface fluxes are minimal, limiting application to data provided by geostationary satellites at sub-hourly temporal resolution. The DTD model has been applied primarily during the active growth phase of agricultural crops and rangeland vegetation grasses, and has not been rigorously evaluated during senescence or in forested ecosystems. In this paper we present modifications to the DTD model that enable applications using thermal observations from polar orbiting satellites, such as Terra and Aqua, with day and night overpass times over the area of interest. This allows the application of the DTD model in high latitude regions where large viewing angles preclude the use of geostationary satellites, and also exploits the higher spatial resolution provided by polar orbiting satellites. A method for estimating nocturnal surface fluxes and a scheme for estimating the fraction of green vegetation are developed and evaluated. Modification for green vegetation fraction leads to significantly improved estimation of the heat fluxes from the vegetation canopy during senescence and in forests. When the modified DTD model is run with LST measurements acquired with the Moderate Resolution Imaging Spectroradiometer (MODIS) on board the Terra and Aqua satellites, generally satisfactory agreement with field measurements is obtained for a number of ecosystems in Denmark and the United States. Finally, regional maps of energy fluxes are produced for the Danish Hydrological ObsErvatory (HOBE) in western Denmark, indicating realistic patterns based on land use

Mean field approach to antiferromagnetic domains in the doped Hubbard model

We present a restricted path integral approach to the 2D and 3D repulsive Hubbard model. In this approach the partition function is approximated by restricting the summation over all states to a (small) subclass which is chosen such as to well represent the important states. This procedure generalizes mean field theory and can be systematically improved by including more states or fluctuations. We analyze in detail the simplest of these approximations which corresponds to summing over states with local antiferromagnetic (AF) order. If in the states considered the AF order changes sufficiently little in space and time, the path integral becomes a finite dimensional integral for which the saddle point evaluation is exact. This leads to generalized mean field equations allowing for the possibility of more than one relevant saddle points. In a big parameter regime (both in temperature and filling), we find that this integral has {\em two} relevant saddle points, one corresponding to finite AF order and the other without. These degenerate saddle points describe a phase of AF ordered fermions coexisting with free, metallic fermions. We argue that this mixed phase is a simple mean field description of a variety of possible inhomogeneous states, appropriate on length scales where these states appear homogeneous. We sketch systematic refinements of this approximation which can give more detailed descriptions of the system.Comment: 14 pages RevTex, 6 postscript figures included using eps

Coherence Time Effects on J/psi Production and Suppression in Relativistic Heavy Ion Collisions

Using a coherence time extracted from high precision proton-nucleus Drell-Yan measurements and a nuclear absorption cross section extracted from pA charmonium production experiments, we study J/psi production and absorption in nucleus-nucleus collisions. We find that coherence time effects are large enough to affect the measured J/psi-to-Drell-Yan ratio. The S+U data at 200A GeV/c measured by NA38 are reproduced quantitatively without the introduction of any new parameters. However, when compared with recent NA50 measurements for Pb+Pb at 158A GeV/c, the data is not reproduced in trend or in magnitude.Comment: 8 pages, 2 figure

Mitochondrial DNA analysis suggests a chibchan migration into Colombia

The characterization of mitochondrial DNA (mtDNA) allows the establishment of genetic structures and phylogenetic relationships in human populations, tracing lineages far back in time. We analysed samples of mtDNA from twenty (20) Native American populations (700 individuals) dispersed throughout Colombian territory. Samples were collected during 1989-1993 in the context of the program Expedición Humana ("Human Expedition") and stored in the Biological Repository of the Institute of Human Genetics (IGH) at the Pontificia Universidad Javeriana (Bogotá, Colombia). Haplogroups were determined by analysis of RFLPs. Most frequent was haplogroup A, with 338 individuals (48.3%). Haplogroup A is also one of the most frequent haplogroups in Mesoamerica, and we interpret our finding as supporting models that propose Chibchan-speaking groups migrated to northern Colombia from Mesoamerica in prehistoric times. Haplogroup C was found in 199 individuals (28.4%), while less frequent were B and D, with 113 and 41 (16% and 6%) individuals, respectively. The haplogroups of nine (9) individuals (1.3%) could not be determined due to the low quality of the samples of DNA. Although all the sampled populations had genetic structures that fit broadly into the patterns that might be expected for contemporary Central and South American indigenous groups, it was found that haplogroups A and B were more frequent in northern Colombia, while haplogroups C and D were more frequent in southern and south-western Colombia

Operator-Based Truncation Scheme Based on the Many-Body Fermion Density Matrix

In [S. A. Cheong and C. L. Henley, cond-mat/0206196 (2002)], we found that the many-particle eigenvalues and eigenstates of the many-body density matrix $\rho_B$ of a block of $B$ sites cut out from an infinite chain of noninteracting spinless fermions can all be constructed out of the one-particle eigenvalues and one-particle eigenstates respectively. In this paper we developed a statistical-mechanical analogy between the density matrix eigenstates and the many-body states of a system of noninteracting fermions. Each density matrix eigenstate corresponds to a particular set of occupation of single-particle pseudo-energy levels, and the density matrix eigenstate with the largest weight, having the structure of a Fermi sea ground state, unambiguously defines a pseudo-Fermi level. We then outlined the main ideas behind an operator-based truncation of the density matrix eigenstates, where single-particle pseudo-energy levels far away from the pseudo-Fermi level are removed as degrees of freedom. We report numerical evidence for scaling behaviours in the single-particle pseudo-energy spectrum for different block sizes $B$ and different filling fractions \nbar. With the aid of these scaling relations, which tells us that the block size $B$ plays the role of an inverse temperature in the statistical-mechanical description of the density matrix eigenstates and eigenvalues, we looked into the performance of our operator-based truncation scheme in minimizing the discarded density matrix weight and the error in calculating the dispersion relation for elementary excitations. This performance was compared against that of the traditional density matrix-based truncation scheme, as well as against a operator-based plane wave truncation scheme, and found to be very satisfactory.Comment: 22 pages in RevTeX4 format, 22 figures. Uses amsmath, amssymb, graphicx and mathrsfs package

A Compact 3H(p,gamma)4He 19.8-MeV Gamma-Ray Source for Energy Calibration at the Sudbury Neutrino Observatory

The Sudbury Neutrino Observatory (SNO) is a new 1000-tonne D2O Cerenkov solar neutrino detector. A high energy gamma-ray source is needed to calibrate SNO beyond the 8B solar neutrino endpoint of 15 MeV. This paper describes the design and construction of a source that generates 19.8-MeV gamma rays using the 3H(p,gamma)4He reaction (``pt''), and demonstrates that the source meets all the physical, operational and lifetime requirements for calibrating SNO. An ion source was built into this unit to generate and to accelerate protons up to 30 keV, and a high purity scandium tritide target with a scandium-tritium atomic ratio of 1:2.0+/-0.2 was included. This pt source is the first self-contained, compact, and portable high energy gamma-ray source (E>10 MeV).Comment: 33 pages (including 2 table, 12 figures) This is the revised manuscript, accepted for publication in NIM A. This revision relfects minor editorial changes from the previous versio