An Online Social Networking Experiment

Online social networking is a pervasive but empirically understudied phenomenon. Strong public opinions on its consequences exist but are backed up by little empirical evidence and almost no causally conclusive, experimental research. The current study tested the psychological effects of posting status updates on Facebook using an experimental design. For 1 week, participants in the experimental condition were asked to post more than they usually do, whereas participants in the control condition received no instructions. Participants added a lab “Research Profile” as a Facebook friend allowing for the objective documentation of protocol compliance, participants’ status updates, and friends’ responses. Results revealed (1) that the experimentally induced increase in status updating activity reduced loneliness, (2) that the decrease in loneliness was due to participants feeling more connected to their friends on a daily basis, and (3) that the effect of posting on loneliness was independent of direct social feedback (i.e., responses) by friends

Integration of System-Dynamics, Aspect-Programming, and Object-Orientation in System Information Modeling

Contemporary information modeling of enterprise systems only focuses on the technical aspect of the systems, though it is known that they are social-technical (socio-tech) systems in essence. In fact, there are many lessons that can be learned from failures in the management of enterprise systems, which range from a small one (e.g., failure to install a printer driver) to a large one (e.g., nuclear power plant post-accident management). This paper, therefore, proposes that the enterprise system should be viewed as a socio-tech system. The paper presents a novel integrated approach to information modeling of socio-tech enterprise systems. In particular, the approach integrates object-orientation, systems-dynamics (as a means to represent high-level dynamics), and aspect-programming. The paper discusses an example to illustrate how the proposed approach works. © 2012 IEEE.published_or_final_versio

Optical Guidance System /OGS/ for rendezvous and docking Final report

Optical guidance system for Apollo rendezvous and dockin

Rolling-sliding laboratory tests of friction modifiers in dry and wet wheel-rail contacts

Friction management has been carried out extensively in the majority of railway networks in the last few years. A popular practice is the application of friction modifiers to increase the adhesion level in contaminated wheel-rail contacts. Two friction modifiers have particularly been used or tested on several railway networks as adhesion enhancers to facilitate the traction and braking operation under poor adhesion conditions. However, for assessment of the performance the railway operators and infrastructure managers mostly rely on practical observations that do not elucidate completely the effectiveness and side effects of these adhesion enhancers. In this paper, the constituents of the two friction modifiers are identified and the solid components are analyzed. A twin-disk roller rig has been used to study their performance in dry and wet contacts under closely controlled laboratory conditions. The adhesion characteristics of both friction modifiers are examined for different slip ratios. Furthermore, the wheel and rail disks are examined after a series of dry tests to analyze the mass loss, the surface damage, the change in surface hardness and roughness, and the subsurface deformation caused by the friction modifiers compared to dry clean contacts. (C) 2009 Elsevier B.V. All rights reserved

[(11)C]PiB PET in Gerstmann-Sträussler-Scheinker disease

Gerstmann-Sträussler-Scheinker Disease (GSS) is a familial neurodegenerative disorder characterized clinically by ataxia, parkinsonism, and dementia, and neuropathologically by deposition of diffuse and amyloid plaques composed of prion protein (PrP). The purpose of this study was to evaluate if [(11)C]Pittsburgh Compound B (PiB) positron emission tomography (PET) is capable of detecting PrP-amyloid in PRNP gene carriers. Six individuals at risk for GSS and eight controls underwent [(11)C]PiB PET scans using standard methods. Approximately one year after the initial scan, each of the three asymptomatic carriers (two with PRNP P102L mutation, one with PRNP F198S mutation) underwent a second [(11)C]PiB PET scan. Three P102L carriers, one F198S carrier, and one non-carrier of the F198S mutation were cognitively normal, while one F198S carrier was cognitively impaired during the course of this study. No [(11)C]PiB uptake was observed in any subject at baseline or at follow-up. Neuropathologic study of the symptomatic individual revealed PrP-immunopositive plaques and tau-immunopositive neurofibrillary tangles in cerebral cortex, subcortical nuclei, and brainstem. PrP deposits were also numerous in the cerebellar cortex. This is the first study to investigate the ability of [(11)C]PiB PET to bind to PrP-amyloid in GSS F198S subjects. This finding suggests that [(11)C]PiB PET is not suitable for in vivo assessment of PrP-amyloid plaques in patients with GSS

Cerebral hypometabolism and grey matter density in MAPT intron 10 +3 mutation carriers

Multiple systems tauopathy with presenile dementia (MSTD), a form of frontotemporal dementia with parkinsonism-17 with tau inclusions (FTDP-17T), is a neurodegenerative disorder caused by an (a) to (g) transition at position +3 of intron 10 of the microtubule associated protein tau (MAPT) gene. The mutation causes overexpression of 4 repeat (4R) tau isoforms with increased 4R/3R ratio leading to neurodegeneration. Clinically, these patients primarily present with behavioral variant FTD (bvFTD) and show disinhibition, disordered social comportment, and impaired executive function, memory, and speech. While altered glucose metabolism has been reported in subjects with sporadic bvFTD, it has yet to be investigated in an FTDP-17 sample of this size. In this study, eleven mutation carriers (5 males; mean age = 48.0 ± 6.9 years) and eight non-carriers (2 males; mean age = 43.7 ± 12.0 years) from a MSTD family were imaged using [(18)F]fluorodeoxyglucose (FDG) positron emission tomography (PET). Eight of the MAPT intron 10 +3 mutation carriers met diagnostic criteria for bvFTD at the time of the PET scan, while three MAPT intron 10 +3 carriers were not cognitively impaired at the time of scan. Non-carriers had no clinically-relevant cognitive impairment at the time of the PET scan. Additionally, ten mutation carriers (5 males; mean age = 48.04 ± 2.1 years) and seven non-carriers (2 males; mean age 46.1 ± 4.1 years) underwent magnetic resonance imaging (MRI) which is an expanded sample size from a previous study. Seven MAPT mutation carriers met diagnostic criteria for bvFTD at the time of the MRI scan. Images were assessed on a voxel-wise basis for the effect of mutation carrier status. SPM8 was used for preprocessing and statistical analyses. Compared to non-carriers, MAPT mutation carriers showed lower [(18)F]FDG uptake bilaterally in the medial temporal lobe, and the parietal and frontal cortices. Anatomical changes were predominantly seen bilaterally in the medial temporal lobe areas which substantially overlapped with the hypometabolism findings. These anatomical and metabolic changes overlap previously described patterns of neurodegeneration in MSTD patients and are consistent with the characteristics of their cognitive dysfunction. These results suggest that neuroimaging can describe the neuropathology associated with this MAPT mutation

The Fine Guidance Sensor, An Electronic Scanning Star Tracker

The advent of space exploration has placed hitherto unheard of requirements on accuracy and precision sensing devices for guidance and attitude control. The necessity for high reliability, due to non-repairability, required new approaches to this design problem. Rather than try to improve upon existing systems, components, and approaches, a totally new concept evolved which eliminates the mechanical rotors and reticles of yesterday. Instead, a totally new breed of electronic scanning star sensor resulted. This paper describes one such device, a Boresighted Star and Planet Tracker developed for precise attitude sensing and control of an experimental sounding rocket. Discussed are the major elements of the basic sensing system, optics, detector, and electronics. The heart of the new sensor is the electronic scanning multiplier phototube, a small, rugged, highly accurate and highly reliable device. Electronic circuit design to enhance accuracy and precision is outlined

What does it mean to be “prepared for work”? Perceptions of new engineers

Background: Engineering education seeks to prepare students for engineering practice, but the concept of preparedness is often ill-defined. Moreover, findings from studies of different populations or in different contexts vary regarding how well new graduates are prepared. These variations, coupled with the lack of clarity, suggest the need to better understand what it means to be prepared for engineering work. Purpose: This study contributes to research on workplace preparation by exploring how new graduates describe being prepared for engineering work. Method: Applying secondary analysis to data from the multi-institution Capstone To Work (C2W) project, we used thematic analysis to explore new engineers\u27 descriptions of preparedness. We analyzed written responses to structured questions about the school-to-work transition collected weekly during participants\u27 first 12 weeks of work; 105 graduates drawn from four universities provided 956 responses, with a mean of 9 (out of 12 possible) responses per participant. Results: Participants\u27 descriptions of preparedness included applying concrete skills, recognizing familiar situations, and having strategies for approaching challenging tasks even when they lacked relevant knowledge or skill. Conclusion: Our findings suggest that although many discussions about workplace preparation implicitly focus narrowly on mastery of skills and knowledge, that focus may not fully capture new graduates\u27 experiences, and may limit discussions about the ways in which school can (and cannot) prepare students for work. A more expansive understanding may better support both student learning and workplace onboarding, though more research is needed across stakeholders to establish shared understanding

Aerodynamic and Aeroacoustic Performance of Small UAV Propellers in Static Conditions

The proliferation of small multi-rotor UAVs in commercial, recreational, and surveillance spheres has garnered significant interest in the noise produced by these vehicles. The current research aims to study the relationship between the aerodynamic performance and acoustic characteristics of small-scale UAV propellers. Three commercially available propellers for the DJI Phantom 2/3 UAV were selected for preliminary development and validation of an aeroacoustic experimental test setup and associated data reduction methods. Propeller thrust, torque, and power measurements were recorded at static conditions. Upon successful validation of the test bench, acoustic measurements were taken at the propeller disk’s upstream and in-plane locations. The power spectral density of these acoustic signals was estimated using the modified periodogram (Welch’s) method to identify frequency content and calculate sound pressure levels (SPLs) at each of the observation locations. Additionally, time-frequency analysis verified the periodogram results and identified possible sources of transient noise at static thrust. These methods found the nonrotor noise to be a major contributor to the SPL at higher frequencies and the propeller noise dominating the SPL spectra at the lower frequencies. Experimental thrust, torque, power, and sound pressure level (SPL) data were then compared for each propeller to identify relationships between aerodynamic performance and acoustic characteristics with variations in propeller geometry and blade loading

Structure and Ionic Conductivity in the Mixed-Network Former Chalcogenide Glass System [Na2S]2/3[(B2S3)x(P2S5)1–x]1/3

Glasses in the system [Na2S]2/3[(B2S3)x(P2S5)1–x]1/3 (0.0 ≤ x ≤ 1.0) were prepared by the melt quenching technique, and their properties were characterized by thermal analysis and impedance spectroscopy. Their atomic-level structures were comprehensively characterized by Raman spectroscopy and 11B, 31P, and 23Na high resolution solid state magic-angle spinning (MAS) NMR techniques. 31P MAS NMR peak assignments were made by the presence or absence of homonuclear indirect 31P–31P spin–spin interactions as detected using homonuclear J-resolved and refocused INADEQUATE techniques. The extent of B–S–P connectivity in the glassy network was quantified by 31P{11B} and 11B{31P} rotational echo double resonance spectroscopy. The results clearly illustrate that the network modifier alkali sulfide, Na2S, is not proportionally shared between the two network former components, B and P. Rather, the thiophosphate (P) component tends to attract a larger concentration of network modifier species than predicted by the bulk composition, and this results in the conversion of P2S74–, pyrothiophosphate, Na/P = 2:1, units into PS43–, orthothiophosphate, Na/P = 3:1, groups. Charge balance is maintained by increasing the net degree of polymerization of the thioborate (B) units through the formation of covalent bridging sulfur (BS) units, B–S–B. Detailed inspection of the 11B MAS NMR spectra reveals that multiple thioborate units are formed, ranging from neutral BS3/2 groups all the way to the fully depolymerized orthothioborate (BS33–) species. On the basis of these results, a comprehensive and quantitative structural model is developed for these glasses, on the basis of which the compositional trends in the glass transition temperatures (Tg) and ionic conductivities can be rationalized. Up to x = 0.4, the dominant process can be described in a simplified way by the net reaction equation P1 + B1 P0 + B4, where the superscripts denote the number of BS atoms for the respective network former species. Above x = 0.4, all of the thiophosphate units are of the P0 type and both pyro- (B1) and orthothioborate (B0) species make increasing contributions to the network structure with increasing x. In sharp contrast to the situation in sodium borophosphate glasses, four-coordinated thioborate species are generally less abundant and heteroatomic B–S–P linkages appear to not exist. On the basis of this structural information, compositional trends in the ionic conductivities are discussed in relation to the nature of the charge-compensating anionic species and the spatial distribution of the charge carriers