Social activity indicators for groupware

Suppose you're a member of a few development teams, working with people who are geographically dispersed. You're using distributed groupware to work with your team mates. How do you decide when to work on a project and when to ignore requests to work on a project, when there are enough users on the groupware system to bother using it, who is available to answer a question, and which applications should get the most real estate on your screen? To help answer these questions, distributed groupware systems must indicate something about the social world they represent-who is on the system and what they are doing. User interfaces for groupware (or computer supported cooperative work (CSCW) applications) must therefore convey social information. It's energizing to know, for example, that your team mates are busy working away on a project. And it's nice to know when your friends or colleagues are available on a chat system. You might not need to know the semantics of the messages or documents involved, just that some activity is occurring. This is true for systems used by work groups as well as those used by an organization or a community of users. We think such social indicators should be a standard part of the CSCW user interface. On the basis of social psychology theory, we believe that a class of social indicator, which we call social activity indicators, is a simple, powerful way to improve user-interface functionality. Furthermore, social activity indicators are easy to build     

Guided-wave optical time delay network

A hybrid optical time delay unit using lithium niobate switches and precisely produced fiber loops is described. Three prototypes of the device were fabricated and characterized. The measured optical extinction ratio between time slots is typically /spl Lt/25 dB. On average, delay values are within 0.7% of their design values. The device is a 6-b (64 time slot) delay unit with 44 picosecond per increment.     

MISR: A multiangle imaging spectroradiometer for geophysical andclimatological research from Eos

The scientific objectives, instrument concept, and data plan for the multiangle imaging spectroradiometer (MISR), an experiment proposed for the Eos (Earth Observing System) mission, are described. MISR is a pushbroom imaging system designed to obtain continuous imagery of the sunlit Earth at four different view angles (25.8°, 45.6°, 60.0°, and 72.5° relative to the vertical at the Earth's surface), in both the forward and aftward directions relative to nadir, using eight separate cameras. Observations will be acquired in four spectral bands, centered at 440, 550, 670, and 860 nm. Data analysis algorithms will be applied to MISR imagery to retrieve the optical, geometric, and radiative properties of complex, three-dimensional scenes, such as aerosol-laden atmospheres above a heterogeneously reflecting surface, nonstratified cloud systems, and vegetation canopies. The MISR investigation will address a number of scientific questions concerning the climatic and ecological consequences of many natural and anthropogenic processes, and will furnish the aerosol information necessary     

Estimation of the local statistical noise in emission computed tomography

A simple modification of the filtered backprojection algorithm is presented for the computation of the local statistical noise in emission computed tomography. The technique is general in that any distribution of radioactivity may be accommodated. When applied to positron emission tomography, it is shown that the effects of photon absorption, random coincidences, radioactive decay, and detector nonuniformity may be included. Calculations have shown the effects of resolution, object size, and photon absorption on the statistical noise of disk-shaped emitters. Comparison of calculation and experiment show close agreement both in magnitude and spatial variation. Measurements of the noise level in tomograms of the brain obtained during continuous inhalation of 150-CO2 demonstrate that estimates of radioactivity concentration with a precision of a few percent are readily attainable.     

Direct Imprinting of Quasi-3D Nanophotonic Structures into Colloidal Quantum-Dot Devices

Three-dimensional (3D) subwavelength nanostructures have emerged and triggered tremendous excitement because of their advantages over the two-dimensional (2D) counterparts in fields of plasmonics, photonic crystals, and metamaterials. However, the fabrication and integration of 3D nanophotonic structures with colloidal quantum dots (CQDs) faces several technological obstacles, as conventional lithographic and etching techniques may affect the surface chemistry of colloidal nanomaterials. Here, the direct fabrication of functional quasi-3D nanophotonic structures into CQD films is demonstrated by one-step imprinting with well-controlled precision in both vertical and lateral directions. To showcase the potential of this technique, diffraction gratings, bilayer wire-grid polarizers, and resonant metal mesh long-pass filters are imprinted on CQD films without degrading the optical and electrical properties of CQD. Furthermore, a dual-diode CQD detector into an unprecedented mid-wave infrared two-channel polarization detector is functionalized by embedding an imprinted bilayer wire-grid polarizer within the CQDs. The results show that this approach offers a feasible pathway to combine quasi-3D nanostructures with colloidal materials-based optoelectronics and access a new level of light manipulation.     

Quantitative analysis of 39 polybrominated diphenyl ethers by isotope dilution GC/low-resolution MS

A GC/low-resolution MS method for the quantitative isotope dilution analysis of 39 mono- to heptabrominated diphenyl ethers was developed. The effects of two different ionization sources, electron impact (EI) and electron capture negative ionization (ECNI), and the effects of their parameters on production of high-mass fragment ions [M - xH - yBr](-) specific to PBDEs were investigated. Electron energy, emission current, source temperature, ECNI system pressure, and choice of ECNI reagent gases were optimized. Previously unidentified enhancement of PBDE high-mass fragment ion [M - xH - yBr](-) abundance was achieved. Electron energy had the largest impact on PBDE high-mass fragment ion abundance for both the ECNI and EI sources. By monitoring high-mass fragment ions of PBDEs under optimized ECNI source conditions, quantitative isotope dilution analysis of 39 PBDEs was conducted using nine (13)C(12) labeled PBDEs on a low-resolution MS with low picogram to femtogram instrument detection limits.     

How to choose cationics for fabric softeners

The choice of a cationic fabric softener for rinse, wash and dryer cycle applications is based upon an understanding of the physical and performance differences of the softeners. These differences are primarily governed by composition of fatty alkyl groups rather than differences in chemical types. In general, the more saturated alkyl fatty groups make softeners more difficult to handle and disperse but are the best for softening fabric. Unsaturation improves handling, rewet, and ease of formulation. Presented at the Feb. 24, 1982 meeting of the Southwest Section of the AOCS at Buena Park, California.     

The long QT syndrome

The LQTS is no longer the rare "zebra" whose purpose is to ensure that trainees recall that deafness and sudden cardiac death may be related (Jervell and Lange-Nielsen syndrome). Over the past 10 to 20 years, the number of cases of inherited LQTS (Romano-Ward syndrome) has increased dramatically. It is doubtful that this reflects a true increase in incidence of disease due to a greater rate of sporadic gene mutations occurring in the heart or because of a rising incidence of consanguinity. Rather, the "incidence" of LQTS has risen because of the emerging awareness of and respect for this electrical malady in the heart. Understanding the principal elements of the LQTS, knowing the types of presentations, and being able to identify its presence electrocardiographically will allow the astute physician to expose this silent killer.     

Efficient enumeration of words in regular languages

The cross-section enumeration problem is to list all words of length n$n$ in a regular language L$L$ in lexicographical order. The enumeration problem is to list the first m$m$ words in L$L$ according to radix order. We present an algorithm for the cross-section enumeration problem that is linear in n+t$n+t$, where t$t$ is the output size. We provide a detailed analysis of the asymptotic running time of our algorithm and that of known algorithms for both enumeration problems. We discuss some shortcomings of the enumeration algorithm found in the Grail computation package. In the practical domain, we modify Mäkinen’s enumeration algorithm to get an algorithm that is usually the most efficient in practice. We performed an extensive performance analysis of the new and previously known enumeration and cross-section enumeration algorithms and found when each algorithm is preferable.