Nonradioactive Northern blotting with biotinylated and digoxigenin-labeled RNA probes

The application of nonradioactive RNA probes for Northern blotting offers the advantage of a rapid turn-around time for results without the loss of sensitivity for target mRNA detection. However, a problem that has impeded the widespread use of nonradioactive RNA probes for use in Northern blotting is the difficulty in stripping these probes from nylon membranes after hybridization. In this report we describe two protocols for stripping digoxigenin (Dig)-labeled RNA probes from nylon membranes. One protocol utilizes a phosphate-buffered formamide stripping solution to remove nonchemically modified (regular) RNA probes while the other method utilizes strippable probes that were produced with a chemically modified nucleotide (CTP) and removed by a specific stripping solution. This latter method was developed by Ambion Inc. and is called Strip-EZ. We also describe a protocol for the detection of two separate rat mRNAs using both biotin and digoxigenin-labeled RNA probes that does not require stripping the membrane after hybridization. Finally, we describe the use of another new labeling technology, called Chem-Link, that quickly and conveniently labels RNA for use in Northern blotting.     

Employee stress and health complaints in jobs with and without electronic performance monitoring

Current applications of electronic performance monitoring based on job design theories that consider worker performance rather than stress issues are likely to generate unsatisfying and stressful jobs (Smith et al, 1986). This study examines critical job design elements that could influence worker stress responses in an electronic monitoring context. A questionnaire survey of employees in telecommunications companies representative of each region in the United States examined job stress in directory assistance, service representative and clerical jobs with specific emphasis on the influence of electronic monitoring of job performance, satisfaction and employee health. Useable surveys were received from 745 employees representing seven operating companies and AT & T; a response rate of about 25%. The results of this survey indicated that employees who had their performance electronically monitored perceived their working conditions as more stressful, and reported higher levels of job boredom, psychological tension, anxiety, depression, anger, health complaints and fatigue. It is postulated that these effects may be related to changes in job design due to electronic performance monitoring.     

Coupling granule properties and granulation rates in high-shear granulation

It is possible to link granulation rates to granule properties. The linkage is by multiple dimension population balance equations that, by means of simplifying assumptions, can be reduced to multiple one-dimensional (1-D) population balance equations (PBEs). Using simple physically based models, this paper demonstrates how multiple one-dimensional population balance equations can describe the results of high-shear granulation experiments of two different materials, calcium carbonate and lactose. Good agreement between experimental and simulated results was achieved enabling the granulation rates to be defined by two model parameters: the critical binder volume fraction and the aggregation rate constant. The modelling framework presented in this paper also provides a basis for the kinetic analysis of granulation experiments so that with further work, it is possible to determine the effect of process conditions and material properties on the model parameters.     

Hydrogen and Oxygen Bubble Attachment to a Bitumen Drop

Air bubble – bitumen attachment is a critical step in the flotation of bitumen from mined oil sand. In this study, single bubble – bitumen drop attachment was observed directly using a novel experimental technique. Induction time is determined and used as an indication of bubble‐bitumen attachment potency for both hydrogen and oxygen bubbles. The attachment tests were conducted in deaerated municipal water (City of Edmonton tap water) at temperatures ranging from 22–50°C. Induction times measured for hydrogen bubble attachment were shorter than those for oxygen bubbles. Coalescence tests were also conducted in the absence of bitumen, and showed that hydrogen bubbles coalesced more rapidly than oxygen bubbles in both deaerated municipal water and clear (solids‐free) process water.     

Examination of superplastic forming combined with diffusion bonding for titanium: Perspective from experience

Superplastic forming (SPF) combined with diffusion bonding (DB) has been used successfully for the fabrication of titanium aerospace hardware. Many of these applications have been for military aircraft, whereby a complex built-up structure has been replaced with monolithic parts. Several methods for applying the two- and four-sheet titanium SPF/DB processes have been devised, including the welding of sheets prior to forming and the use of silk-screened stop-off (yttria) to prevent bonding where it is undesirable. Very little progress has been made in the past few years toward understanding and modeling the SPF/DB process using constitutive equations and data by laboratory testing. Concerns that engineers face in designing for fatigue life, acceptable design loads, and damage tolerance are currently being studied, but the database is very limited. This is a summary of past work found in the literature and forms the foundation for additional research. This paper was presented at the International Symposium on Superplasticity and Superplastic Forming sponsored by the Manufacturing Critical Sector at the ASM International AeroMat 2004 Conference and Exposition, June 8–9, 2004, in Seattle, WA. The symposium was organized by Daniel G. Sanders, The Boeing Company.     

Oxidation of a dilute aluminum magnesium alloy

The morphology and composition of the oxide film formed under various oxidation conditions on a 1.2% aluminum-magnesium alloy have been studied using electron microscopy and diffraction. Below 350° C the oxide film formed is highly protective and amorphous, while above this temperature the oxide becomes nonprotective. Initially, at temperatures above 350°C, the oxide film consists of only alumina, then with increasing time it contains first MgO, then MgO together with MgAl₂O₄, and finally it is entirely converted to MgAl₂O₄.     

STXXL: standard template library for XXL data sets

We present the software library STXXL that is an implementation of the C++ standard template library (STL) for processing huge data sets that can fit only on hard disks. It supports parallel disks, overlapping between disk I/O and computation and it is the first I/O‐efficient algorithm library that supports the pipelining technique that can save more than half of the I/Os. STXXL has been applied both in academic and industrial environments for a range of problems including text processing, graph algorithms, computational geometry, Gaussian elimination, visualization, and analysis of microscopic images, differential cryptographic analysis, etc. The performance of STXXL and its applications are evaluated on synthetic and real‐world inputs. We present the design of the library, how its performance features are supported, and demonstrate how the library integrates with STL. Copyright © 2007 John Wiley & Sons, Ltd.     

Brain stem integration of vocalization: role of the nucleus retroambigualis

1. The descending pathways that mediate the periaqueductal gray (PAG)-evoked coordination of respiratory, laryngeal, and orofacial activity for vocalization have yet to be delineated. Two hypotheses have been offered. One theory is that this activity is mediated by a diffuse descending projection to parvocellular reticular interneurons, adjacent to the relevant laryngeal and orofacial motoneuronal pools. The second hypothesis is that the motor activity for vocalization is integrated via a projection from the PAG to a caudal medullary column of neurons, the nucleus retroambigualis (NRA). These hypotheses were tested with the use of a series of medullary transections combined with PAG stimulation. Transections that eliminated, in a series of caudal-to-rostral steps, the NRA, also eliminated the PAG-evoked cricothyroid and most of the thyroarytenoid laryngeal motor activity. These results indicate that the final common pathway for much of the laryngeal activity in PAG-evoked vocalization includes un initial synapse in the caudal medulla, presumably in the NRA. 2. The electromyographic changes evoked by microinjection of D,L-homocysteic acid (DLH) in the NRA of the unanesthetized, precollicular decerebrate cat were analyzed in order to delineate the NRA contribution to the coordinated respiratory, laryngeal, and oral muscle changes in vocalization. A total of 415 DLH injection sites were located at or caudal to the level of the obex. Vocalization was evoked at 46 of these sites, which were all confined to a restricted region of the ventrolateral medulla 1-3 mm caudal to the obex. This region corresponded to the rostral half of the NRA and the immediately adjacent medullary tegmentum. 3. In all experiments evidence was obtained that variable muscle activation, rather than functional and integrated muscle patterns, was represented within the NRA. Vocalization evoked by DLH microinjection in the NRA was usually associated with excitation of the cricothyroid, thyroarytenoid, external oblique, internal oblique, internal intercostal, and diaphragm muscles that occurred in a different manner from site to site. That is, injection at sites separated by 0.3-0.5 mm evoked quite different responses. 4. NRA-evoked vocalization was compared with PAG-evoked vocalization using small injections (1.5-4.5 nl) into each region. As well, larger microinjections (15-120 nl) into NRA were made for comparison with previous results from the PAG using similar doses. Within the PAG, stereotyped and relatively "fixed" patterns of muscle activity are represented, whereas within the NRA there was no representation of specific muscle patterns, but rather a partial topographic separation of "premotor neurons" regulating different muscles. Correspondingly, stereotyped vocalizations were never evoked from the NRA. Further, most NRA-evoked vocalizations were unusual in quality and would not be identified generally as feline. 5. Evidence was obtained for a separation of pathways from the PAG regulating sound production and orofacial modulation of that sound. In contrast to the results from the PAG, excitation of NRA neurons rarely evoked activity in the oral muscles (genioglossus or anterior belly of digastric) or orofacial modulation of sound production. 6. Our finding suggests that the NRA serves as an important substrate for the generation of respiratory pressure and larynges adduction, which are two essential aspects of not only vocalization but also several behaviors involving Valsava maneuvers such as coughing, vomiting, and defecation.