HD 4915: A Maunder Minimum Candidate

We study the magnetic activity cycle of HD 4915 using the \ion{Ca}{2} H \& K emission line strengths measured by Keck I/HIRES spectrograph. The star has been observed as a part of California Planet Search Program from 2006 to present. We note decreasing amplitude in the magnetic activity cycle, a pattern suggesting the star's entry into a Magnetic Grand Minimum (MGM) state, reminiscent of the Sun's Maunder and Dalton Minima. We recommend further monitoring of the star to confirm the grand minimum nature of the dynamo, which would provide insight into the state of the Sun's chromosphere and the global magnetic field during its grand minima. We also recommend continued observations of H \& K emission lines, and ground or space based photometric observations to estimate the sunspot coverage.Comment: To be submitted to AAS Journals; comments welcom

Membrane Dipole Potentials

Molecular and Cellular Biolog

How to Track Bacteria

A microscope is described which automatically remains focused on individual motile bacteria. The container in which the bacteria are suspended is moved in such a way that the position of a given organism remains fixed; x, y, and z drive signals provide a measure of its displacement relative to the suspension medium. Records are shown of the motion of Escherischia coli.Molecular and Cellular Biolog

Parallelization of a Maximum Parsimony Branch and Bound Algorithm for Phylogenetic Inference

Phyiogenetic inference involves the reconstruction of evolutionary relationships among species in the form of branching diagrams called trees. Specifically, certain biological structures common to all living organisms, such as morphological characteristics, protein sequences or DNA sequences can be compared Differences and similarities in these characteristics among species are used to reconstruct the evolutionary relationships and draw trees. Many methods of tree reconstruction are currently used. The method of maximum parsimony for phyiogenetic inference is a widely used algorithm which employs the hypothesis that the most likely tree for a given group of data will be the one which uses the least number of changes from an origin (root of the tree) to the terminal taxa The problems and corresponding solution algorithms associated with these searches are frequently implemented on single-processor systems, and can take weeks to complete for large data sets. Parallelization of these algorithms is therefore an important area of development in the bioinformatics community [1, 3, 17, 20, 25]. A free license, open-source, parallel implementation of a phyiogenetic inference program using maximum parsimony has yet to be developed, and it is the aim of this thesis to provide such a tool. It is hoped that the tool will work transparently with one of the most popular suites of free phyiogenetic inference tools called PHYLIP, developed by Joe Felsenstein at the University of Washington [7], by accepting and generating the same format of input and output data The tool would be a first step towards providing the academic community and others with improvements in performance and capabilities (through parallelization) over the currently available free distributions of phyiogenetic inference programs using parsimony, allowing for larger volumes of data to be analyzed in a reduced amount of time

CHANGES IN THICKNESS OF THE RED BLOOD CORPUSCLE MEMBRANE

Measurements of the static capacity per cm.2 of membrane for the red corpuscle as changed when the cells are made spherical by the addition of lecithin or rose bengal, show a slight increase of capacity, indicating a thinning of the membrane, although the change is not large enough to make it certain that it is real. Furthermore, the membrane capacity shows a slight decrease when spherical cells are swollen in hypotonic saline, indicating a thickening of the membrane, although the change is hardly outside the experimental error. The fact that there is no increase in capacity lends support to the theory that as the cell swells the membrane does not stretch but new material comes from the interior of the cell to make a new portion of the membrane

Academic Researchers and the First Amendment: Constitutional Protection for Their Confidential Sources

The first section of this Comment describes the Richards decision. As will be seen, that decision reflects the exercise of judicial discretion to ensure that the quest for discovery under the Federal Rules of Civil Procedure does not override other important interests. The validity of that exercise is then examined. Finally, this Comment addresses the constitutional privilege issue left unanswered by Richards. It advances the thesis that academic researchers deserve a qualified first amendment privilege against compulsory disclosure of their confidential sources

Ultrasensitivity of an Adaptive Bacterial Motor

The flagellar motor of Escherichia coli adapts to changes in the steady-state level of the chemotaxis response regulator, CheY-P, by adjusting the number of FliM molecules to which CheY-P binds. Previous measurements of motor ultrasensitivity have been made on cells containing different amounts of CheY-P and, thus, different amounts of FliM in flagellar motors. Here, we designed an experiment to measure the sensitivity of motors containing fixed amounts of FliM, finding Hill coefficients about twice as large as those observed before. This ultrasensitivity provides further insights into the motor switching mechanism and plays important roles in chemotaxis signal amplification and coordination of multiple motors. The Hill coefficients observed here appear to be the highest known for allosteric protein complexes, either biological or synthetic. Extreme motor ultrasensitivity broadens our understanding of mechanisms of allostery and serves as an inspiration for future design of synthetic protein switches.Molecular and Cellular BiologyPhysic

Forced Axial Flow Between Rotating Concentric Cylinders

Forced axial flow in an annular gap of a cylindrical rotor is investigated analytically and experimentally. At small rotation rates and narrow gap widths, the axial flow is a simple Poiseuille flow over most of the rotor. The distance required for this Poiseuille flow to get established is estimated. An instability is observed at large rotation rates with certain input geometries.Molecular and Cellular Biolog