Multidimensional spectroscopy with a single broadband phase-shaped laser pulse

We calculate the frequency-dispersed nonlinear transmission signal of a phase-shaped visible pulse to fourth order in the field. Two phase profiles, a phase-step and phase-pulse, are considered. Two dimensional signals obtained by varying the detected frequency and phase parameters are presented for a three electronic band model system. We demonstrate how two-photon and stimulated Raman resonances can be manipulated by the phase profile and sign, and selected quantum pathways can be suppressed.Comment: 26 pages, 15 figure

Organizing information on the next generation web - Design and implementation of a new bookmark structure

The next-generation Web will increase the need for a highly organized and ever evolving method to store references to Web objects. These requirements could be realized by the development of a new bookmark structure. This paper endeavors to identify the key requirements of such a bookmark, specifically in relation to Web documents, and sets out a suggested design through which these needs may be accomplished. A prototype developed offers such features as the sharing of bookmarks between users and groups of users. Bookmarks for Web documents in this prototype allow more specific information to be stored such as: URL, the document type, the document title, keywords, a summary, user annotations, date added, date last visited and date last modified. Individuals may access the service from anywhere on the Internet, as long as they have a Java-enabled Web browser

Spin-resolved electron-impact ionization of lithium

Electron-impact ionization of lithium is studied using the convergent close-coupling (CCC) method at 25.4 and 54.4 eV. Particular attention is paid to the spin-dependence of the ionization cross sections. Convergence is found to be more rapid for the spin asymmetries, which are in good agreement with experiment, than for the underlying cross sections. Comparison with the recent measured and DS3C-calculated data of Streun et al (1999) is most intriguing. Excellent agreement is found with the measured and calculated spin asymmetries, yet the discrepancy between the CCC and DS3C cross sections is very large

Comparison of experiment and theory for superelastic electron-collision studies from laser-aligned magnesium

A combined experimental and theoretical study of superelastic electron collisions from laser-aligned magnesium atoms for a range of collision energies from 35 to 55 eV is presented. 24Mg atoms were excited from the 3 1S0 ground state to the 3 1P1 excited state using continuous-wave linearly polarized laser radiation at ∼285 nm. Electrons of well-defined energy Einc then deexcited the targets, and the superelastically scattered electrons emerging from the collision were detected as a function of scattering angle and laser polarization. Results for alignment of the target by the electron beam are presented for a range of scattering angles, for outgoing energies from Eout=35 to 55 eV. The agreement between the measurements and the results of the convergent close-coupling theory are encouraging, but some discrepancies remain

Browsing Icons: A Task-Based Approach for a Visual Web History

We have implemented a task and session based visual web history tool called Browsing Icons that dynamically draws animated graphs of the user's paths through the web. Using a proxy, it can be attached to any common web browser. Every web session builds an individual Browsing Graph with a characteristic shape. The graphs are organized in a hierarchy of user-defined tasks. Users can interrupt tasks and continue later using the graphs that provide access to all the web pages they have visited so far. The graphs can be reused for similar or recurrent tasks. By clustering the history hierarchically according to tasks, we try to cope with scale and to provide a powerful concept for easy revisitation. The visualizations have been implemented using the Jazz framework for zoomable user interfaces (ZUIs) in Java. A usability study showed that users like the system very much and appreciate its support of revisiting web pages. Ten users revisited web pages after a few minutes and other web pages after one to six days using both Netscape with Browsing Icons and Netscape alone. With the tool they completed the short-term revisits in 84% of the time required when using Netscape alone. The revisits after one to six days users could accomplish in 57.8% of the time they needed when using Netscape, thereby visiting only 53.8% as many pages. Users were significantly more satisfied with Browsing Icons than with pure Netscape. KEYWORDS: Web History Visualization, Task Based Information Organization, Information Visualization, Web Browser Usability, Jazz. UMIACS-TR-2001-85 HCIL-TR-2001-1

Learning Analytics and iSchools: What, Why, & Worries

This SIE is aimed at members of the iSchool community who are interested in learning about Learning Analytics (LA) and thinking through how this arena for Big Data is relevant to the intellectual agenda(s) undertaken by iSchools. We expect that attendees will leave the session with an understanding of what learning analytics is, why LA is relevant to iSchools, and how we can design structures that support the ethical use of these tools. We will reach the broader conference community by designing the SIE to be spread over two days where the participants will query other conference colleagues between the two sessions and report back at the second session. The activity between sessions will be based on ethical scenarios described below supported by simple and specific tasks that participants will be given.ye

Favorite Folders: A Configurable, Scalable File Browser

Microsoft Windows Explorer, the most widely used file browser in Microsoft Windows, shows almost all directories in the file system. However, most users usually access only a subset of the directories in their machine. If the file browser shows only the directories users are interested in, they can select the directory they want more easily and quickly. This paper introduces a configurable, scalable file system explorer that reduces selection time by showing only the directories users want to see. We give users an easy way to hide directories behind a special ellipsis node. In addition, those hidden directories are one click away. We present a preliminary field study conducted to validate the concept of Favorite Folders and a theoretical model to predict the performance times. Keywords: Windows Explorer, file browser, adaptive interfaces, customizable interfaces UMIACS-TR-2003-38 HCIL-TR-2003-1

AN EVALUATION OF MARYLAND'S NEW VOTING MACHINE

Four counties in Maryland used new touch screen voting machines in the 2002 elections, replacing their mechanical lever and punch card voting systems with the AccuVote-TS touch screen voting machine manufactured by Diebold Election Systems. The Center for American Politics and Citizenship (CAPC) and the Human-Computer Interaction Lab (HCIL) at the University of Maryland conducted an exit poll in Montgomery and Prince George's counties to evaluate the performance of the new voting machines. In this second of two reports prepared by CAPC and HCIL on the new voting machines, we found that most voters like the new voting machines and trust them to accurately record their votes. However, a significant number of voters still have concerns about the new machines, many needed help using them, and some continue to report technical problems with the machines. Voters who do not frequently use computers or have not attended college had the most difficulty using the machines. Major Findings: * Seven percent of voters felt that the touch screen voting machine was not easy to use, compared to 93 percent who felt it was easy to use or held a neutral opinion. * Nine percent of voters did not trust the touch screen voting machine, compared to with 91 percent who did. Only 70 percent trusted the mechanical lever or punch card system they previously used. * Three percent of voters reported encountering technical problems with the new machines. * Nine percent of the voters asked for and 17 percent received assistance using the new machine. * More than one-quarter of the voters who use computers once a month or less received assistance using the voting machine. * One-third of voters who have not attended college received assistance using the voting machine. * Voters in Prince George's County found the election judges to be more helpful than did voters in Montgomery County. Four counties in Maryland used new touch screen voting machines in the 2002 elections. Alleghany, Dorchester, Montgomery, and Prince George's replaced their mechanical lever and punch card voting systems with the AccuVote-TS touch screen voting machine manufactured by Diebold Election Systems. All 24 of Maryland's counties will purchase AccuVote-TS voting machines by 2006. The University of Maryland conducted an exit poll in Montgomery and Prince George's Counties to assess the performance of the new voting machine. Our sample included 1,276 respondents from 22 precincts in the two counties. The response rate was 74.6 percent. (UMIACS-TR-2002-107) (HCIL-TR-2002-25

Ordered and Quantum Treemaps: Making Effective Use of 2D Space to Display Hierarchies (2001)

Treemaps, a space- filling method of visualizing large hierarchical data sets, are receiving increasing attention. Several algorithms have been proposed to create more useful displays by controlling the aspect ratios of the rectangles that make up a treemap. While these algorithms do improve visibility of small items in a single layout, they introduce instability over time in the display of dynamically changing data, fail to preserve order of the underlying data, and create layouts that are difficult to visually search. In addition, continuous treemap algorithms are not suitable for displaying quantum-sized objects within them, such as images. This paper introduces several new treemap algorithms, which address these shortcomings. In addition, we show a new application of these treemaps, using them to present groups of images. The ordered treemap algorithms ensure that items near each other in the given order will be near each other in the treemap layout. Using experimental evidence from Monte Carlo trials, we show that compared to other layout algorithms ordered treemaps are more stable while maintaining relatively favorable aspect ratios of the constituent rectangles. A second test set uses stock market data. The quantum treemap algorithms modify the layout of the continuous treemap algorithms to generate rectangles that are integral multiples of an input object size. The quantum treemap algorithm has been applied to PhotoMesa, an application that supports browsing of large numbers of images

Single Display Groupware

We discuss a model for supporting collaborative work between people that are physically close to each other. We call this model Single Display Groupware (SDG). In this paper, we describe the model, comparing it to more traditional remote collaboration. We describe the requirements that SDG places on computer technology, and our understanding of the benefits and costs of SDG systems. Finally, we describe a prototype SDG system that we built and the results of a usability test we ran with 60 elementary school children. Through participant observation, video analysis, program instrumentation, and an informal survey, we discovered that the SDG approach to collaboration has strong potential. Children overwhelmingly prefer two mice to one mouse when collaborating with other children. We identified several collaborative styles including a dominant partner, independent simultaneous use, a mentor/mentee relationship, and active collaboration. (Also cross-referenced as UMIACS-TR-99-75