Organically modified silica sol-mediated capillary electrophoresis

We describe in this paper the use of ormosil (organically modified silica) sols as additives to the run buffer for selectivity manipulations between solutes in capillary electrophoresis. CE systems that contain sol additives in the run buffer can be thought of as pseudocapillary electrochromatography. Three sols based on different types of silanes were studied. Methyltrimethoxysilane (MTMOS)-based sol was found to improve selectivities between various aromatic acids. Aminopropyltrimethoxysilane (APS) sol interacts differently with structural isomers of aromatic acids than does MTMOS. At low pH with APS sol in the run buffer, neutral solutes can be separated, as well. The separation of the neutral solutes seems to be facilitated by the formation of hydrogen bonds between the solutes and the APS sol. APS and N-[3-(trimethoxysilyl)propyl]-ethylenediamine (EDAS) affect the separation of the same compounds differently, thus indicating that even small changes of the functional groups of the sol have pronounced effect on the interactions between the sols and the solutes.     

Deviant auditory stimuli activate human left and right auditory cortex differently

Infrequent "deviant' auditory stimuli embedded in a homogeneous sequence of "standard' sounds evoke a neuromagnetic mismatch field (MMF), which is assumed to reflect automatic change detection in the brain. We investigated whether MMFs would reveal hemispheric differences in cortical auditory processing. Seven healthy adults were studied with a whole-scalp neuromagnetometer. The sound sequence, delivered to one ear at time, contained three infrequent deviants (differing from standards in duration, frequency, or interstimulus interval) intermixed with standard tones. MMFs peaked 9-34 msec earlier in the right than in the left hemisphere, irrespective of the stimulated ear. Whereas deviants activated only one MMF source in the left hemisphere, two temporally overlapping but spatially separate sources, one in the temporal lobe and another in the inferior parietal cortex, were necessary to explain the right-hemisphere MMFs. We suggest that the bilateral MMF components originating in the supratemporal cortex are feature specific whereas the right-hemisphere parietal component reflects more global auditory change detection. The results imply hemispheric differences in sound processing and suggest stronger involvement of the right than the left hemisphere in change detection.     

Database as a genre of new media

After the novel, and subsequently cinema privileged narrative as the key form of cultural expression of the modern age, the computer age introduces its correlate — database. Why does new media favour database form over others? Can we explain ist popularity by analysing the specificity of the digital medium and of computer programming? What is the relationship between database and another form, which has traditionally dominated human culture — narrative? In addressing these questions, I discuss the connection between computer's ontology — the way software represents the world — and the new cultural forms privileged by computer culture such as database. I propose that computerisation of culture involves projection of two fundamental parts of computer software — data structures and algorithms — onto the cultural sphere. Thus CD-ROMs and Web databases are cultural manifestations of one half of this ontology — data structures; while new media narratives are manifestations of the second part — algorithms. I conclude by proposing that in computer culture database and narrative do not have the same status. Given that on the level of data organisation most new media objects are databases, it is not surprising that on the level of form database also dominates new media culture.     

ON BROADWAY

On Broadway represents life in the 21st century city through a compilation of images and data collected along the 13 miles of Broadway that span Manhattan. The result is a new type of city view, created from the activities and media shared by hundreds of thousands of people. The project uses approximately 40 million data points and images and includes an application and an interactive installation.     

Fluorescent dye labeled bacteriophages--a new tracer for the investigation of viral transport in porous media: 1. Introduction and characterization

A new method for the study of pathogen transport in porous media is presented. The method is based on conjugation of fluorescent dyes to target bacteriophages and application of the modified bacteriophages for tracer studies. We demonstrate that the relevant transport determining properties of Rhodamine and several fluorescein-labeled phages are practically identical to those of the native bacteriophages. The advantages of the proposed method relative to direct enumeration of bacteriophages by plaque forming unit method, turbidity, fluorescent microspheres, and other alternative tracers are discussed. Notable advantages include simple quantitation by optical methods, unbiased signals even when virus aggregates are formed, and the ability to decouple inactivation kinetics from transport phenomena. Additionally, the signal reflects the removal and transport of the studied microorganism and not a surrogate.     

NSOM the fourth dimension: Integrating nanometric spatial and femtosecond time resolution

Photonic devices are becoming the cornerstone of next generation systems for computing and information processing. This paper reports on the first steps in the development of methods to understand these devices with nanometric (10^?7 cm) spatial and femtosecond (10^?15 s) time resolution. The basis of this achievement is the dramatic developments that have occurred in the past few years in a new area of optics called near-field optics. Near-field optics is a form of lensless optics with a resolution that is subwavelength and which is independent of the wavelength of the light being employed. We report in this paper the transmission of pulses with tens of femtosecond duration through subwavelength, near-field optical elements. We also report on a femtosecond near-field optical light source with cross-correlating capabilities and on the growth of GaAs in the tip of micropipettes for use as an ultra-fast electro-optical switch which can cross-correlate optical, electrical, and electro-optical effects. These developments are especially relevant in the investigation of photonic devices since such devices can alter their characteristics as a function of size in the mesoscopic regime from just below lens-based optical resolutions to dimensions that approach atomic scales of ～1 nm (10^?7 cm). In view of the fact that these devices and the processes that govern them also exhibit ultrafast speeds, the combination of state of the art femtosecond laser spectroscopy with the unique features of near-field optics is a critical step in advancing our next generation understandings of such materials and structures so that their full potential in information processing can be achieved.     

Preparation of Photodegradable Oligomers Containing Metal–Metal Bonds Using ADMET

ADMET was evaluated as a method for preparing organometallic polymers with metal–metal bonds in the main chain. The Cp₂Mo₂CO₄(Ph₂P(CH₂)₆CH=CH₂)₂ complex was synthesized, and the X-ray crystal structure is reported. The molecule did not undergo ADMET polymerization with Grubbs’ or Schrock’s catalysts. In a control experiment to test if the Ph₂P(CH₂)₆CH=CH₂ ligand was interfering with the ADMET reaction, the phosphine was reacted with Grubbs’ 2nd generation catalyst. The dimerized metathesis product Ph₂P(CH₂)₆CH=CH(CH₂)₆PPh₂ was obtained with no observed degradation or deactivation of the catalyst. To test the inherent ADMET reactivity of the Ph₂P(CH₂)₆CH=CH₂ ligand when it is bonded to a metal center, the mononuclear cis-Mo(CO)₄(Ph₂P(CH₂)₆CH=CH₂)₂ complex was synthesized and polymerized using Grubbs’ 2nd generation catalyst. These control experiments suggest that the inability of Cp₂Mo₂CO₄(Ph₂P(CH₂)₆CH=CH₂)₂ to polymerize is not due to electronic effects pertaining to the C=C unit of the Ph₂P(CH₂)₆CH=CH₂ ligand. Accordingly, steric effects are implicated in the inability of the Cp₂Mo₂CO₄(Ph₂P(CH₂)₆CH=CH₂)₂ to polymerize by ADMET.     

Size bounds for superconcentrators

We prove that any N-superconcentrator of indegree two has at least 4N - o(N) nodes. From this lower bounds of 4N - o(N) follow on the number of additions required to compute the Discrete Fourier Transform of prime order and cyclic convolution. Using small examples we illustrate how small superconcentrators can suggest fast algorithms for instances of these problems.For superconcentrators with no degree restrictions we prove a lower bound of 5N - o(N) edges. Also, we give a recursive construction with 3Nlog₂N edges that improves on the best bounds previously known for values of N up to several thousand.