PC-based FT/ICR system

An apparatus for conducting FT/ICR experimentation and acquiring data using a personal computer and a fast buffer board. The apparatus has the capability of generating an ion excitation signal and acquiring results from the FT/ICR experiment. Those results are then digitized and stored in memory on the fast buffer board. Once the results have been stored in the fast buffer board memory, they are transferred to the personal computer where they can be processed and interpreted by the user

PC-based FT/ICR system

An apparatus for conducting FT/ICR experimentation and acquiring data using a personal computer and a fast buffer board. The apparatus has the capability of generating an ion excitation signal and acquiring results from the FT/ICR experiment. Those results are then digitized and stored in memory on the fast buffer board. Once the results have been stored in the fast buffer board memory, they are transferred to the personal computer where they can be processed and interpreted by the user

Stacked-ring electrostatic ion guide

In 1969 Bahr, Gerlich, and Teloy introduced an rf device that consisted of a stack of ring electrodes, with charge sign alternation between neighboring rings, to store or transport ions. Here we propose to operate such a device with electrostatic potentials rather than rf potentials: ions that move axially along the center of the guide are thereby subjected to an oscillating electrical potential similar to the sinusoidal rf potential in familiar rf-only multipole ion guides. The oscillating potential of the stacked-ring static ion guide focuses ions by exerting a field gradient force on the ions so as to push ions toward the central axis where the field is weakest. The stacked-ring ion guide produces an effectively static “pseudopotential” that is much steeper at the edge (potential varies as er) compared to a quadrupole or octupole guide (for which the potential varies as r2 or r6, where r is radial position) and that is much flatter near the center of the guide (for potentially higher ion flux). Advantages of the new ion guide include static rather than rf potential, low electrical noise, a large field-free region near the central axis of the guide, and simple mechanical construction. A disadvantage of the stacked-ring ion guide is that high ion axial kinetic energy is required; ions with axial kinetic energy that is too low may be trapped in the shallow pseudopotential well between adjacent ring electrodes

Sympathetic cooling of trapped negative ions by self-cooled electrons in a fourier transform ion cyclotron resonance mass spectrometer

Hot electrons confined in a Penning trap at 3 tesla self-cool to near room temperature in a few seconds by emission of cyclotron radiation. Here, we show that such cold electrons can “sympathetically” cool, in ~10 s, laser desorbed/ionized translationally hot Au− or C70− ions confined simultaneously in the same Penning trap. Unlike “buffer gas” cooling by collisions between ions and neutral gas molecules, sympathetic cooling by electrons is mediated by the mutual long-range Coulomb interaction between electrons and ions, so that translationally hot ions can be cooled without internal excitation and fragmentation. It is proposed that electrosprayed multiply charged macromolecular ions can be cooled sympathetically, in the absence of ion-neutral collisions, by self-cooled electrons in a Penning trap

SIRT6 stabilizes DNA-dependent Protein Kinase at chromatin for DNA double-strand break repair

The Sir2 chromatin regulatory factor links maintenance of genomic stability to life span extension in yeast. The mammalian Sir2 family member SIRT6 has been proposed to have analogous functions, because SIRT6-deficiency leads to shortened life span and an aging-like degenerative phenotype in mice, and SIRT6 knockout cells exhibit genomic instability and DNA damage hypersensitivity. However, the molecular mechanisms underlying these defects are not fully understood. Here, we show that SIRT6 forms a macromolecular complex with the DNA double-strand break (DSB) repair factor DNA-PK (DNA-dependent protein kinase) and promotes DNA DSB repair. In response to DSBs, SIRT6 associates dynamically with chromatin and is necessary for an acute decrease in global cellular acetylation levels on histone H3 Lysine 9. Moreover, SIRT6 is required for mobilization of the DNA-PK catalytic subunit (DNA-PKcs) to chromatin in response to DNA damage and stabilizes DNA-PKcs at chromatin adjacent to an induced site-specific DSB. Abrogation of these SIRT6 activities leads to impaired resolution of DSBs. Together, these findings elucidate a mechanism whereby regulation of dynamic interaction of a DNA repair factor with chromatin impacts on the efficiency of repair, and establish a link between chromatin regulation, DNA repair, and a mammalian Sir2 factor

Fourier transform ion cyclotron resonance mass spectrometry: Personal computer-based instrument and two-dimensional spectroscopy

A personal computer based Fourier transform ion cyclotron resonance mass spectrometer has been designed and constructed. An IBM PC AT compatible computer is used to host the interface of the instrument. The advantages of using a personal computer to host the FT-ICR instrument include: (1) very low cost of the computer; (2) extensive graphic and mathematic capabilities; (3) easy performance alteration or expansion; (4) an abundance of application software; and (5) support for a wide range of output devices. A dedicated digital hardware interface, which provides high speed data transfer and accurate timing control, was assembled on the computer\u27s extension board. The extension board is used to replace the frequency synthesizers and waveform recorders normally used for arbitrary waveform generation and data acquisition at a speed of several mega Hertz. The unique features of the digital hardware design include: (1) common memory for both excitation and data acquisition; (2) control logic for critical timing steps; (3) system memory mapping for fast data transfer. This design has not only led to great reduction in construction cost but has increased the flexibility of the instrument to perform complex experiments as well. A general phase modulation algorithm for the stored waveform inverse Fourier transform (SWIFT) excitation has been developed. The method can be used to generate arbitrary excitation waveforms with optimal dynamic range reduction. The maximum entropy spectral analysis (MEM) has been investigated. When the broad-band MEM method was demonstrated in the host computer, resolution and signal-to-noise ratio improvement was observed. New preamplifier, electron beam circuits, and the sample inlet system of the instrument were designed and constructed with computer control. This provides the instrument with reliability, stability, and functionality. A theoretical model for two dimensional Fourier transform ion cyclotron resonance mass spectrometry has been proposed. The model interprets the physical significance of the modulation of the ion signals in the additional dimension. According to the model, the additional time dimension (which is introduced as the duration between the pair of 2D excitation pulses) determines the speed of the primary ions just before the reaction period. The speed modulation may result in primary ion population modulation. In general, the speed modulation will transfer into ion signal modulation through a variety of channels, such as reactions and ion loss. The model also predicts that the ion modulation in the additional dimension is not sinusoidal (therefore, harmonics exist) and the ion signal modulation has definite phase relationships. The implementation of the 2D technique is developed and demonstrated

Healthcare decision-making and the older person

Background This report outlines the results of a collaborative research project undertaken by Dr John Lombard of the School of Law University of Limerick, and Age Action Ireland. The project explored healthcare decision-making and the older person, in particular, it examined the older person’s experience of autonomy and consent in healthcare, familiarity with decision-making practices, and awareness of forthcoming decision-making supports. The purpose of this empirical research was to gauge perceptions of autonomy, to identify aspects of healthcare decision-making which raise greatest concern for the older person, and to determine whether there is a lack of understanding surrounding aspects of the legal framework. The research project was therefore shaped by three core objectives: 1. To explore the older person’s understanding of autonomy in healthcare, familiarity with decision-making practices, and awareness of forthcoming decision-making supports. 2. To identify the priorities, concerns and needs of the older person around this topic 3. To identify shortcomings between the legal framework and the subjective experience of research participants The experience and views of the older person were captured through quantitative researchPUBLISHEDnon-peer-reviewe

Machine fluid sensor and method

A method for analyzing a fluid contained within a machine, comprising the steps of providing a machine system (100) including a passage (104) for containing a fluid; placing a sensor (106) including a mechanical resonator in the passage; operating the resonator to have a portion thereof translate through the fluid; and monitoring the response of the resonator to the fluid in the passage. One specific sensor includes a tuning fork resonator