The prevalence of BANA‐hydrolyzing periodontopathic bacteria in smokers

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/99012/1/j.1600-051X.1999.tb02526.x.pd

The Interaction between the ISM and Star Formation in the Dwarf Starburst Galaxy NGC 4214

We present the first interferometric study of the molecular gas in the metal-poor dwarf starburst galaxy NGC 4214. Our map of the 12CO(1-0) emission, obtained at the OVRO millimeter array, reveals an unexpected structural wealth. We detected three regions of molecular emission in the north-west (NW), south-east (SE) and centre of NGC 4214 which are in very different and distinct evolutionary stages (total molecular mass: 5.1 x 10^6 M_sun). These differences are apparent most dramatically when the CO morphologies are compared to optical ground based and HST imaging: massive star formation has not started yet in the NW region; the well-known starburst in the centre is the most evolved and star formation in the SE complex started more recently. We derive a star formation efficiency of 8% for the SE complex. Using high--resolution VLA observations of neutral hydrogen HI and our CO data we generated a total gas column density map for NGC 4214 (HI + H_2). No clear correlation is seen between the peaks of HI, CO and the sites of ongoing star formation. This emphasizes the irregular nature of dwarf galaxies. The HI and CO velocities agree well, so do the H-alpha velocities. In total, we cataloged 14 molecular clumps in NGC 4214. Our results from a virial mass analysis are compatible with a Galactic CO-to-H_2 conversion factor for NGC 4214 (lower than what is usually found in metal-poor dwarf galaxies).Comment: accepted for publication in the AJ (February 2001), full ps file at: ftp://ftp.astro.caltech.edu/users/fw/ngc4214/walter_prep.p

Microbial fuel cells continuously fuelled by untreated fresh algal biomass

© 2015. Microbial fuel cells (MFCs) are energy transducers that convert organic matter directly into electricity, via the anaerobic respiration of electro-active microorganisms. An avenue of research in this field is to employ algae as the organic carbon fuel source for the MFCs. However, in all studies demonstrating the feasibility of this principle, the algal biomass has always been pre-treated prior to being fed to MFCs, e.g. centrifuged, dried, ground into powder, and/or treated by acid-thermal processes. The alternative presented here, is a flow-through system whereby the MFCs were continuously fed by fresh algal biomass. The system consisted of i) a culture of Synechococcus leopoliensis grown continuously in a photo-chemostat, ii) a pre-digester initiating the digestion of the phototrophs and producing a fuel devoid of oxygen, and iii) a cascade of 9 MFCs, hydraulically and electrically independent. This compartmental system could in theory produce 42W of electrical power per cubic metre of fresh culture (6·10 5 cellsmL -1 )

Factors which are associated with dental decay in the older individual

Objectives: To improve reliability of salivary bacterial cultures as a surrogate for plaque levels of cariogenic bacterial species by reporting the salivary CFUs of these organisms as a function of the number of teeth. Design: Cross-sectional collection of data in a convenience sample of adults over 60 years of age. Setting: Hospital Dental clinic, University bacteriology laboratory. Subjects: 523 older dentate subjects, average age 70, including 412 subjects who were in an independent living status and 111 in a dependent-living situation. Main outcome measures : Subjects were examined for decay and the presence of salivary factors including the levels of S. mutans , lactobacilli, yeast and other bacteria. The salivary levels of the bacteria were adjusted for the number of teeth in the mouth, and the resultant values were entered into multivariable logistic regression models along with clinical and other salivary parameters. Results: Mutans streptococci levels reported as CFUs/ml saliva per tooth were significantly associated with coronal surface decay, and lactobacilli, reported in a similar way, were significantly associated with root surface decay. Salivary levels of yeasts, which had previously been associated with decay in this population, were no longer significant using this construct. Conclusions : This construct of reporting salivary bacteriological data as a function of tooth number and per ml saliva could improve the reliability of bacteriological data obtained in epidemiological studies investigating the role of bacteria in dental decay in the elderly.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72626/1/j.1741-2358.1999.00037.x.pd

Measurements of the instantaneous velocity difference and local velocity with a fiber-optic coupler

New optical arrangements with two single-mode input fibers and a fiber-optic coupler are devised to measure the instantaneous velocity difference and local velocity. The fibers and the coupler are polarization-preserving to guarantee a high signal-to-noise ratio. When the two input fibers are used to collect the scattered light with the same momentum transfer vector but from two spatially separated regions in a flow, the obtained signals interfere when combined via the fiber-optic coupler. The resultant light received by a photomultiplier tube contains a cross-beat frequency proportional to the velocity difference between the two measuring points. If the two input fibers are used to collect the scattered light from a common scattering region but with two different momentum transfer vectors, the resultant light then contains a self-beat frequency proportional to the local velocity at the measuring point. The experiment shows that both the cross-beat and self-beat signals are large and the standard laser Doppler signal processor can be used to measure the velocity difference and local velocity in real time. The new technique will have various applications in the general area of fluid dynamics.Comment: Patent number: 67437 for associated information on the hardware, see http://karman.phyast.pitt.edu/horvath

Detection of fast radio transients with multiple stations: a case study using the Very Long Baseline Array

Recent investigations reveal an important new class of transient radio phenomena that occur on sub-millisecond timescales. Often transient surveys' data volumes are too large to archive exhaustively. Instead, an on-line automatic system must excise impulsive interference and detect candidate events in real-time. This work presents a case study using data from multiple geographically distributed stations to perform simultaneous interference excision and transient detection. We present several algorithms that incorporate dedispersed data from multiple sites, and report experiments with a commensal real-time transient detection system on the Very Long Baseline Array (VLBA). We test the system using observations of pulsar B0329+54. The multiple-station algorithms enhanced sensitivity for detection of individual pulses. These strategies could improve detection performance for a future generation of geographically distributed arrays such as the Australian Square Kilometre Array Pathfinder and the Square Kilometre Array.Comment: 12 pages, 14 figures. Accepted for Ap