6,850 research outputs found
CIT-5: a high-silica zeolite with 14-ring pores
The synthesis and structure of a new zeolite, CIT-5 (California Institute of Technology Number Five), is described, which possesses one-dimensional pores comprised of 14 T-atoms (tetrahedrally coordinated silicon or aluminium atoms)
Least Reliable Bits Coding (LRBC) for high data rate satellite communications
An analysis and discussion of a bandwidth efficient multi-level/multi-stage block coded modulation technique called Least Reliable Bits Coding (LRBC) is presented. LRBC uses simple multi-level component codes that provide increased error protection on increasingly unreliable modulated bits in order to maintain an overall high code rate that increases spectral efficiency. Further, soft-decision multi-stage decoding is used to make decisions on unprotected bits through corrections made on more protected bits. Using analytical expressions and tight performance bounds it is shown that LRBC can achieve increased spectral efficiency and maintain equivalent or better power efficiency compared to that of Binary Phase Shift Keying (BPSK). Bit error rates (BER) vs. channel bit energy with Additive White Gaussian Noise (AWGN) are given for a set of LRB Reed-Solomon (RS) encoded 8PSK modulation formats with an ensemble rate of 8/9. All formats exhibit a spectral efficiency of 2.67 = (log2(8))(8/9) information bps/Hz. Bit by bit coded and uncoded error probabilities with soft-decision information are determined. These are traded with with code rate to determine parameters that achieve good performance. The relative simplicity of Galois field algebra vs. the Viterbi algorithm and the availability of high speed commercial Very Large Scale Integration (VLSI) for block codes indicates that LRBC using block codes is a desirable method for high data rate implementations
Reliability and Validity of Angular Joint Velocity Using Peak Motus 2000 Motion Analysis and Kin-Com Isokinetic Dynamometer
Background and Purpose: Use of motion analysis systems for the study of human motion in research settings and clinical settings is becoming more prevalent. In a traditional sense, motion analysis systems are used for gait analysis; most recently, they are being utilized to analyze spinal motion, foot motion, and components of motion during sporting activities. Questions about the accuracy of computerized motion analysis systems and the precision and reliability of the digitizing process remains. The purpose of this study is to determine the validity of the Peak Motus 2000 motion analysis system in calculating dynamic velocities and range of motion.
Methods: Six healthy subjects (three females and three males) had reflective markers placed on the right ankle joint. Video cameras filmed the subject\u27s ankle movements while on the Kin-Com Isokinetic Dynamometer. The subjects were taken through five repetitions each of the following passive speeds: 60, 150, and 240 degrees/second. The Kin-Com Isokinetic Dynamometer was then utilized in a passive mode without subjects by placing reflective markers on the lever arm. The Peak Motus 2000 motion analysis computer software program was used from recorded video motion with a subject attached to the apparatus to determine angular joint velocity. Statistical analysis was completed comparing data sets.
Results: In summary, the compiled standard deviation values from lowest to highest are Kin-Com, Peak Performance lever arm and Peak Performance skin marker measurement. This indicates that subject motion analyzed by skin marker angular velocity measurements had a greater variability and therefore a higher chance of being inaccurate. It was found that the Peak Performance had a trend towards overestimating set angular velocities, which became larger as the speed was increased.
Conclusion: This study found that at 60 degrees/second there was no significant difference in reported angular velocity between the Kin-Com and the Peak Performance and a significant difference in reported angular velocity at 150 and 240 degrees/second. It also showed that the Peak Performance tended to be more accurate at lower speeds and decreased in accuracy as the speeds increased. The Peak Performance system generally overestimated the angular velocity at each speed
Effect of weathering product assemblages on Pb bioaccessibility in mine waste: implications for risk management
General assessments of orebody types and associated mine wastes with regards to their environmental signature and human health hazards are needed to help managing present and historical mine waste facilities.
Bioaccessibility tests and mineralogical analysis were carried out on mine waste from a systematic sampling of mine sites from the Central Wales orefield, UK.
The bioaccessible Pb widely ranged from 270 to 20300 mg/kg (mean 7250 mg/kg; median 4890 mg/kg) and the bioaccessible fraction from 4.53 % to >100 % (mean 33.2 %; median 32.2 %), with significant (p=0.001) differences among the mine sites. This implies sensitivity of bioaccessibility to site-specific conditions and suggests caution in the use of models to assess human health impacts generalised on the basis of the mineral deposit type. Mineralogical similarities of the oxidation products of primary galena provided a better control over the observed Pb bioaccessibility range. The higher Pb bioaccessibility (%) was related to samples containing cerussite, irrespective of the presence of other Pb minerals in the mineral assemblage; lower Pb bioaccessibility resulted where anglesite was the main Pb mineral phase and cerussite was absent.
A solubility diagram for the various Pb minerals in the waste was derived using PHREEQC model and the experimental Pb concentration measured in the simulated gastric solution compared with the equilibrium modelling results. For samples containing cerussite, the model well predicted the soluble Pb concentrations measured in the experimental simulated gastric solution, indicative of the carbonate mineral phase control on the Pb in solution for these samples and little kinetic control on the dissolution of cerussite. On the contrary, most mine waste samples containing dominant anglesite and or plumbojarosite (no cerussite) had lower solution Pb values, falling at or below the anglesite and plumbojarosite solubility equilibrium concentrations, implying kinetic or textural factors hindering the dissolution
Virtual Assisted Self Interviewing (VASI): An Expansion of Survey Data Collection Methods to the Virtual Worlds by Means of VDCI
Changes in communication technology have allowed for the expansion of data collection modes in survey research. The proliferation of the computer has allowed the creation of web and computer assisted auto-interview data collection modes. Virtual worlds are a new application of computer technology that once again expands the data collection modes by VASI (Virtual Assisted Self Interviewing). The Virtual Data Collection Interface (VDCI) developed at Indiana University in collaboration with the German Socio-Economic Panel Study (SOEP) allows survey researchers access to the population of virtual worlds in fully immersive Heads-up Display (HUD)-based survey instruments. This expansion needs careful consideration for its applicability to the researcher's question but offers a high level of data integrity and expanded survey availability and automation. Current open questions of the VASI method are an optimal sampling frame and sampling procedures within e. g. a virtual world like Second Life (SL). Further multi-modal studies are proposed to aid in evaluating the VDCI and placing it in context of other data collection modes.Interviewing mode, PAPI, CAPI, CASI, VASI, VDCI, second life
Virtual Assisted Self Interviewing (VASI): An Expansion of Survey Data Collection Methods to the Virtual Worlds by Means of VDCI
Changes in communication technology have allowed for the expansion of data collection modes in survey research. The proliferation of the computer has allowed the creation of web and computer assisted auto-interview data collection modes. Virtual worlds are a new application of computer technology that once again expands the data collection modes by VASI (Virtual Assisted Self Interviewing). The Virtual Data Collection Interface (VDCI) developed at Indiana University in collaboration with the German Socio-Economic Panel Study (SOEP) allows survey researchers access to the population of virtual worlds in fully immersive Heads-up Display (HUD)-based survey instruments. This expansion needs careful consideration for its applicability to the researcher’s question but offers a high level of data integrity and expanded survey availability and automation. Current open questions of the VASI method are an optimal sampling frame and sampling procedures within e. g. a virtual world like Second Life (SL). Further multimodal studies are proposed to aid in evaluating the VDCI and placing it in context of other data collection modes.Interviewing Mode, PAPI, CAPI, CASI, VASI, VDCI, Second Life
Surveying The Virtual World. A Large Scale Survey in Second Life Using the Virtual Data Collection Interface (VDCI)
Technology has always introduced changes in the way researchers administer surveys. A new technology known as virtual worlds has now emerged that promises to change data collection once again. Virtual worlds are persistent, online, computer-rendered spaces populated by hundreds, thousands, or even millions of people at a time. Previously, this population has only been surveyed in ways that required respondents to exit the virtual world before giving their answers. No survey method has existed whereby they could be surveyed while remaining present in the virtual space. Needless to say, this is less than ideal for any survey about the respondent’s attitudes, perceptions, and behavior within the virtual world itself. This study introduces a method for solving this problem and a tool that allows surveys entirely within a virtual environment. The method is introduced as Virtual Assisted Self Interview (VASI), and the tool for implementing it, the Virtual Data Collection Interface (VDCI). The tool was created and deployed in the virtual world Second Life (SL), where users were asked questions about demographics and quality of life. The valid response numbers for the survey (N=2094) make it the largest in-virtualworld data collection seen so far. This paper discusses the VDCI and describes several different sampling methods, as well as results that provide unique, new insights into virtual world populations. It is found, for example, that the demographic make-up of SL is unlike that of other virtual worlds. Moreover, the SL population is unlike that of other worlds in its approach to gender-switching. The limitations and new hazards of virtual world survey research are also discussed, especially survey "hacking" by individuals hoping to exploit the survey for financial gain. Despite the challenges, the results generally suggest that the VDCI is a valuable new research tool for obtaining representative data on virtual world population.VASI, VDCI, Second Life, Survey Plan, Fieldwork
STRUCTURAL BASIS OF SUBSTRATE RECOGNITION IN THIMET OLIGOPEPTIDASE AND DEVELOPMENT OF NANOPARTICLES FOR THERAPEUTIC ENZYME DELIVERY
Neuropeptidases are responsible for degradation of signaling peptides in the central nervous system and periphery. Some neuropeptidases have also been shown to play a role as part of the cell’s hydrolytic machinery responsible for breaking down proteins and peptides into amino acids, and these enzymes therefore influence small peptide availability for antigen presentation. A better understanding of how neuropeptidases recognize their substrates could lead to therapeutics that modulate the activity of these important enzymes. Alternatively, re-engineering these enzymes to selectively hydrolyze undesirable peptides could make them attractive as therapeutics themselves. A key question in understanding the activity of these enzymes is how they are able to recognize a variety of seemingly unrelated amino acid sequences as cleavage sites. We are investigating the basis for this general substrate recognition in neuropeptidases using thimet oligopeptidase (TOP) as a model. Crystal structures of TOP in complex with a variety of substrates and inhibitors shed light on the mechanisms underlying substrate recognition and pave the way for re-targeting substrate recognition in these enzymes.
Nano test tube particles have been proposed as a means of delivering therapeutics such as enzymes. However, the template synthesis method for nano test tube production does not produce therapeutic quantities. In order to take full advantage of re-engineered neuropeptidases a new method for nano test tube synthesis has been developed. We show that a non-destructive template synthesis methodology can be applied to produce nano test tube particles in quantities useful for therapeutic enzyme immobilization
Hemispheric asymmetries in faculty and student musicians and nonmusicians during melody recognition tasks : a thesis ...
Cu,rrent research has suggested that musical stimuli are processed in the right hemisphere except in musicians, in whom there is an increased involvement of the left hemisphere. The present study hypothesized that the more musical training persons receive, the 1 more they will rely on an analytic/left hemispheric processing strategy. The subjects were 10 faculty and 10 student nonmusicians, and 10 faculty and 10 student musicians. All subjects listened to a series of melodies (some recurring and some not) and excerpts (some real and some fake) in one ear and to a different series of melodies in the other ear. The task was to identify recurring vs. nonrecurring melodies and real vs. fake excerpts. For student musicians, there was a_ left ear/right hemispheric advantage for melody recognition, while for student nonmusicians, the situation was the reverse. Neither faculty group showed any ear preference. There were no significant differences for excerpt recognition. Two plausible explanations of the faculty performance were discussed in terms of a maturation factor and a functionally more integrated hemispheric approach to the task
- …