Specifying Exposure Classification Parameters for Sensitivity Analysis: Family Breast Cancer History

One of the challenges to implementing sensitivity analysis for exposure misclassification is the process of specifying the classification proportions (eg, sensitivity and specificity). The specification of these assignments is guided by three sources of information: estimates from validation studies, expert judgment, and numerical constraints given the data. The purpose of this teaching paper is to describe the process of using validation data and expert judgment to adjust a breast cancer odds ratio for misclassification of family breast cancer history. The parameterization of various point estimates and prior distributions for sensitivity and specificity were guided by external validation data and expert judgment. We used both nonprobabilistic and probabilistic sensitivity analyses to investigate the dependence of the odds ratio estimate on the classification error. With our assumptions, a wider range of odds ratios adjusted for family breast cancer history misclassification resulted than portrayed in the conventional frequentist confidence interval.Children's Cancer Research Fund, Minneapolis, MN, US

Field-Immersed Targets (CE-30)

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Copper vapor laser drilling of copper, iron, and titanium foils in atmospheric pressure air and argon

A copper vapor laser (511 and 578 nm) is used to drill submillimeter diameter holes in 0.025–0.127 mm thick foils of copper, iron, and titanium. Foils are machined in atmospheric pressure air and argon. The laser is repetitively pulsed at 10 kHz with a per pulse energy of 0.5 mJ giving an average power of 5 W at the sample surface for a pulse width of 40 ns. A p‐i‐n photodiode and a photomultiplier tube detector are connected to a digital‐display timing circuit that records the number of incident laser pulses used to drill through the sample. The number of pulses is converted to an average drilling time and can provide an estimate for the average laser energy used to drill the hole. Typical data for all three materials with a per‐pulse fluence of 0.7 J/cm2 ranged from 0.1 to 500 s to produce holes of ∼0.3 mm diameter. Drilling times decreased in some cases by an order of magnitude when machining in air. This is attributed to the increased laser absorption of the metal‐oxide layer formed in air and was especially noticeable with titanium. A continuous wave thermal model is used to compare experimental data as well as verify the thermal machining mechanism.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69638/2/RSINAK-64-11-3308-1.pd

Shifting new media: from content to consultancy, from heterarchy to hierarchy

This is a detailed case history of one of London’s iconic new media companies, AMX Studios. Some of the changes in this firm, we assume, are not untypical for other firms in this sector. Particularly we want to draw attention to two transformations. The first change in AMX and in London’s new media industry more generally refers to the field of industrial relations. What can be observed is a shift from a rather heterarchical towards a more hierarchical organized new media industry, a shift from short-term project networks to long-term client dependency. The second change refers to new media products and services. We want to argue for a shift from cool content production towards consultancy and interactive communications solutions

Ionization dynamics of iron plumes generated by laser ablation versus a laser‐ablation‐assisted‐plasma discharge ion source

The ionization dynamics (iron ion and neutral atom absolute line densities) produced in the KrF excimer laser ablation of iron and a laser‐ablation‐assisted plasma discharge (LAAPD) ion source have been characterized by a new dye‐laser‐based resonant ultraviolet interferometry diagnostic. The ablated material is produced by focusing a KrF excimer laser (248 nm,<1 J, 40 ns) onto a solid iron target. The LAAPD ion source configuration employs an annular electrode in front of the grounded target. Simultaneous to the excimer laser striking the target, a three‐element, inductor–capacitor, pulse‐forming network is discharged across the electrode–target gap. Peak discharge parameters of 3600 V and 680 A yield a peak discharge power of 1.3 MW through the laser ablation plume. Iron neutral atom line densities are measured by tuning the dye laser near the 271.903 nm (a 5D–y 5P0) ground‐state and 273.358 nm (a 5F–w 5D0) excited‐state transitions while iron singly ionized line densities are measured using the 263.105 nm (a 6D–z 6D0) and 273.955 nm (a 4D–z 4D0) excited‐state transitions. The line density, expansion velocity, temperature, and number of each species have been characterized as a function of time for laser ablation and the LAAPD. Data analysis assuming a Boltzmann distribution yields the ionization ratio (ni/nn) and indicates that the laser ablation plume is substantially ionized. With application of the discharge, neutral iron atoms are depleted from the plume, while iron ions are created, resulting in a factor of ∼5 increase in the plume ionization ratio. Species temperatures range from 0.5 to 1.0 eV while ion line densities in excess of 1×1015 cm−2 have been measured, implying peak ion densities of ∼1×1015 cm−3. © 1996 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70077/2/JAPIAU-79-5-2287-1.pd

Laser‐ablation‐assisted‐plasma discharges of aluminum in a transverse‐magnetic field

Laser‐ablation‐assisted‐plasma discharges (LAAPD) have been used to enhance the ionization of laser ablated aluminum metal. Ablation is accomplished by focusing a KrF excimer laser (248 nm, 40 ns, ≤0.4 J) on a solid aluminum target with a fluence of 4 J/cm2. Peak plasma discharge voltage is 1–4 kV and peak plasma current is 0.2–1 kA, while peak power is 0.1–1 MW. Gated emission spectroscopy is used to determine the charge states and the electronic temperatures within the plasma discharge. With unmagnetized discharge parameters of 3 kV and 760 A, the observed light emission is dominated by transitions from Al2+ ions indicating nearly complete ionization of the plume. From the emission spectra intensities, an Al2+ electronic temperature of 3.3 eV is determined. Emission spectra from unmagnetized LAAPD of 1.2 kV and 280 A show no visible Al2+ ion transitions indicating cooler plasma and a lower ionization state. Introducing a 620 G transverse magnetic field (at 1.2 kV, 280 A) enhances the ionization due to the increased electron confinement and leads to the observance of the Al2+ lines as seen with discharges of 3 kV and 760 A.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70075/2/APPLAB-65-5-531-1.pd

The Impact of Individual Employee Differences on Information Seeking in Today’s Information Rich Work Environment

Recent advancements in information and communication technologies (ICT) such as video conferencing, email, instant messaging, and Intranets have dramatically changed the landscape of communication in most organizations. The objective of this study is to gain an understanding of how different types of organizational members seek information. This is necessary ifor the management to provide the right infrastructure and processes to support such information needs. This study adds to the body of literature on information seeking behavior by incorporating gender, and cultural variables as well as the organizational variables of organizational status (salary or wage) and newcomer status. The findings will help management in assessing what ICT should be installed in order to provide the appropriate support to facilitate information and knowledge dissemination and sharing in organizations

Effects of laser‐ablation target damage on particulate production investigated by laser scattering with deposited thin film and target analysis

Experiments have been carried out to correlate ablated particulate density and size to the number of KrF excimer laser (248 nm, 40 ns, <1.2 J) pulses incident on a single location of a pure solid aluminum target and to relate particulate production to target surface damage. An analysis of laser ablation deposited aluminum films on silicon substrates was used to determine the density of ablated particulate greater than 0.5 μm in diameter. For an undamaged target, the laser deposited particulate density was on the order of 8.6×105 cm−2 per 1000 shots. A damaged target (following 1000 laser pulses) produced a density on the order of 1.6×106 cm−2 per 1000 shots on the substrate. Dye laser optical scattering was also used to measure, in real time, the velocity of the particulate and the relative particulate density in the laser‐ablation plume versus target damage. Results indicated a rapid rise in the production of particulate as target damage was increased up to 3000 laser pulses; after this number of shots the density of particulate in the laser ablation plume saturated. A peak in the scattered light for each stage of target damage occurred 40 μs after the initial KrF laser pulse, translating to a velocity of about 100 m/s for the smaller particulate (<1 μm diameter). The later scattered signal, around 160 μs, was apparently due to the larger particulate (5–15 μm), traveling at a velocity of approximately 25 m/s. Particulate production is related to the formation of laser ablation‐induced cones on the damaged targets. © 1996 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70140/2/APPLAB-68-23-3245-1.pd