On fiber diameters of continuous maps

We present a surprisingly short proof that for any continuous map $f : \mathbb{R}^n \rightarrow \mathbb{R}^m$, if $n>m$, then there exists no bound on the diameter of fibers of $f$. Moreover, we show that when $m=1$, the union of small fibers of $f$ is bounded; when $m>1$, the union of small fibers need not be bounded. Applications to data analysis are considered.Comment: 6 pages, 2 figure

Studies of Alkaline Phosphatase Inhibition by Metal Chelators using Capillary Electrophoresis

Alkaline phosphatase inhibition by metal chelators has been studied using capillary electrophoresis. The enzyme-inhibition assays were performed by electrophoretically mixing enzyme and inhibitor zones in a substrate filled capillary. Enzyme inhibition could be seen as a decrease in product formation as detected using laser-induced fluorescence. The enzyme-inhibition assays were adapted so they could be performed using a commercial CE system. Use of a commercial system is desirable for these assays due to ease of use and system features such as autosamplers and capillary and sample cooling. This technique could prove useful for pharmaceutical industries as a screening tool for new drug therapies. Six metal chelators were studied as enzyme inhibitors using CE enzyme-inhibition assays. EDTA inhibition assays performed previously on a laboratory constructed CE system were compared to those using a commercial system. The assays performed on the commercial system showed irreversible inhibition at concentrations of 1.0 mM or less and activation at 2.0 mM. The opposite trend was seen with the laboratory constructed system. One hypothesis to explain this discrepancy is that two different water sources contained different concentrations of metal contaminants. The two water sources were used due to equipment failure making one source unavailable. The common metal chelators EGTA, NTA, and 1,10-phenanthroline all exhibited reversible inhibition of alkaline phosphatase at concentrations of 0.08 to 2.0 mM. Crown ethers, which are not commonly used as enzyme inhibitors, were also studied. 12-crown-4 and 18-crown-6 both reversibly inhibited alkaline phosphatase at concentrations of 0.08 to 0.3 mM. The reversible inhibition exhibited by the various chelators examined (excluding EDTA) could be due to a time dependent mechanism in which Zn2+, which is required by ALP, is slowly removed, rendering the enzyme inactive. Alkaline phosphatase inhibition was also studied using on-column reagent addition. The enzyme was added on-column, through a gap reactor and mixed with the fluorescent enzyme substrate, Attophos, and zones of inhibitor. Theophylline, a reversible noncompetitive inhibitor, and sodium vanadate, a reversible competitive inhibitor were used. Enzyme inhibition could be easily seen as a decrease in product formation detected by laser-induced fluorescence

Functional requirements for onboard management of space shuttle consumables, volume 1

A study was conducted to determine the functional requirements for onboard management of space shuttle consumables. A generalized consumable management concept was developed for application to advanced spacecraft. The subsystems and related consumables selected for inclusion in the consumables management system are: (1) propulsion, (2) power generation, and (3) environmental and life support

Spin Torque Dynamics with Noise in Magnetic Nano-System

We investigate the role of equilibrium and nonequilibrium noise in the magnetization dynamics on mono-domain ferromagnets. Starting from a microscopic model we present a detailed derivation of the spin shot noise correlator. We investigate the ramifications of the nonequilibrium noise on the spin torque dynamics, both in the steady state precessional regime and the spin switching regime. In the latter case we apply a generalized Fokker-Planck approach to spin switching, which models the switching by an Arrhenius law with an effective elevated temperature. We calculate the renormalization of the effective temperature due to spin shot noise and show that the nonequilibrium noise leads to the creation of cold and hot spot with respect to the noise intensity.Comment: 10 pages, 7 figure

Controlling the Kondo Effect in CoCu_n Clusters Atom by Atom

Clusters containing a single magnetic impurity were investigated by scanning tunneling microscopy, spectroscopy, and ab initio electronic structure calculations. The Kondo temperature of a Co atom embedded in Cu clusters on Cu(111) exhibits a non-monotonic variation with the cluster size. Calculations model the experimental observations and demonstrate the importance of the local and anisotropic electronic structure for correlation effects in small clusters.Comment: 4 pages, 4 figure

Applying Domain Knowledge from Structured Citation Formats to Text and Data Mining: Examples Using the CITE Architecture

Domain knowledge expressed in structured citation formats can be exploited in data mining. We propose four structural properties of canonically cited texts, then look at to two classic problems in the study of the scholia, or ancient scholarly commentary, found in the manuscripts of the Iliad. We cluster citations of scholia to analyze their distribution in different manuscripts; this leads to a revised view of how the manuscripts\u27 scribes drew on their source material. Correlated frequencies of named entities suggest that one group of manuscripts had access to material more closely based on the work of the greatest Hellenistic editor of Homer, Aristarchus of Samothrace