-
[show abstract]
[hide abstract]
ABSTRACT: Rodent whisking behavior generates two types of neural signals: one produced by whisker contact with objects; the other by movements in air. While kinematic signals generated by contact reliably activate neurons at all levels of the trigeminal neuraxis, the extent to which the kinematics of whisking in air are reliably encoded at each level remains unclear. Previously, we showed that the responses of trigeminal ganglion (TG) neurons in awake, head-fixed rats are correlated with whisking kinematic parameters, but that individual neurons may differ substantially in the reliability of their kinematic encoding. Here, we extend that analysis to neurons in the ventral posterior medial (VPM) nucleus. Three possible coding strategies were examined: (1) firing rate across an entire movement; (2) the probability of individual spikes as a function of the instantaneous movement trajectory; and (3) the coherence between spikes and whisking. While VPM neurons were clearly responsive to variations in whisker kinematics during whisking in air, the encoding of whisker kinematics by VPM neurons was less consistent than that of TG neurons. Furthermore, we found that, in VPM as in TG, movement direction is an important determinant of unit responsiveness during whisking in air.
Somatosensory & Motor Research 01/2010; 27(3):111-20. · 1.11 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Designing Web sites that are responsive to customer needs is a critical prerequisite for the success of online services. Recently, a usability evaluation procedure, based on the Microsoft usability guidelines (MUG) has emerged. MUG identifies five design requirements - content, ease of use, made-for-the-medium, emotion, and promotion - that should increase the usability of sites. To date, however, there has been limited research examining why online customers would place more or less importance on these requirements. In addition to demographic characteristics which may help explain customer needs, we propose that psychographic characteristics will also influence usability-related requirements. To develop our research model and hypotheses, we draw from recent usability literature and research in consumer behavior concerned with customers' beliefs about technology, specifically focusing on four beliefs - optimism, innovativeness, discomfort, and insecurity. We present the results of our study, involving 215 subjects, which examined the influence of customer characteristics on usability requirements.
Hawaii International Conference on System Sciences, Proceedings of the 41st Annual; 02/2008
-
[show abstract]
[hide abstract]
ABSTRACT: Geospatio-temporal conceptual models provide a mechanism to explicitly represent geospatial and temporal aspects of applications. Such models, which focus on both "what" and "when/where," need to be more expressive than conventional conceptual models (e.g., the ER model), which primarily focus on "what" is important for a given application. In this study, we view conceptual schema comprehension of geospatio-temporal data semantics in terms of matching the external problem representation (that is, the conceptual schema) to the problem-solving task (that is, syntactic and semantic comprehension tasks), an argument based on the theory of cognitive fit. Our theory suggests that an external problem representation that matches the problem solver's internal task representation will enhance performance, for example, in comprehending such schemas. To assess performance on geospatio-temporal schema comprehension tasks, we conducted a laboratory experiment using two semantically identical conceptual schemas, one of which mapped closely to the internal task representation while the other did not. As expected, we found that the geospatio-temporal conceptual schema that corresponded to the internal representation of the task enhanced the accuracy of schema comprehension; comprehension time was equivalent for both. Cognitive fit between the internal representation of the task and conceptual schemas with geospatio-temporal annotations was, therefore, manifested in accuracy of schema comprehension and not in time for problem solution. Our findings suggest that the annotated schemas facilitate understanding of data semantics represented on the schema.
IEEE Transactions on Professional Communication 07/2006; · 0.66 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: This paper describes efforts to develop a pedagogical environment that seeks to influence the learning experiences of students as mobile applications end users, developers, and decision makers. Specifically, via a collaborative effort involving industry sponsors, university technology services, and multiple academic units engaged in information technology education, a graduate-level course called Mobile Applications Development (MAD) was created. The core innovativeness of MAD lies in its delivery structure as a problem-based learning course-centered on emerging technologies like mobile technology-that brings together students with diverse backgrounds from different academic units across the campus. MAD culminates in an industry-sponsored competition, where student teams present their mobile solution to a panel of expert judges from industry and higher education. Via MAD and the associated competitions, students, faculty, and institutional partners can explore the opportunities and challenges associated with mobile technologies. This paper discusses how problem-based learning principles guided the design and implementation of MAD. A multiperspective assessment of the success of MAD is offered. Finally, key lessons learned and guidance to assist other educators are also offered
IEEE Transactions on Education 06/2006; · 1.02 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The mobile-phone industry cannot rely solely on growth in subscriber demand for voice service. Rather, a potential new source of revenue - mobile data services - is being introduced. Carriers and content providers have made significant investments and advances to enable next generation data or "wireless Web" services and mobile, "m", - commerce. In this paper, we focus on two areas related to the m-commerce experience: the technology readiness (TR) of consumers and wireless Web interface usability. We propose that TR - the propensity of consumers to embrace and use new technologies - may provide explanations of consumer needs and desires as related to usability. We present the results of a study in which we examine this relationship as well as how TR affects web and wireless Web site evaluations. Ultimately, a deeper understanding of the TR-usability relationship may facilitate the efforts of carriers and content providers regarding mobile data marketing and design strategies.
System Sciences, 2005. HICSS '05. Proceedings of the 38th Annual Hawaii International Conference on; 02/2005
-
[show abstract]
[hide abstract]
ABSTRACT: While many real-world applications need to organize data based on space (e.g., geology, geomarketing, environmental modeling) and/or time (e.g., accounting, inventory management, personnel management), existing conventional conceptual models do not provide a straightforward mechanism to explicitly capture the associated spatial and temporal semantics. As a result, it is left to database designers to discover, design, and implement - on an ad hoc basis - the temporal and spatial concepts that they need. We propose an annotation-based approach that allows a database designer to focus first on nontemporal and nongeospatial aspects (i.e., "what") of the application and, subsequently, augment the conceptual schema with geospatiotemporal annotations (i.e., "when" and "where"). Via annotations, we enable a supplementary level of abstraction that succinctly encapsulates the geospatiotemporal data semantics and naturally extends the semantics of a conventional conceptual model. An overarching assumption in conceptual modeling has always been that expressiveness and formality need to be balanced with simplicity. We posit that our formally defined annotation-based approach is net only expressive, but also straightforward to understand and implement.
IEEE Transactions on Knowledge and Data Engineering 12/2004; 16(11):1324- 1338. · 1.66 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Stereotactic core biopsy (SCB) is more cost-effective than needle-localized biopsy (NLB) for evaluation and treatment of mammographic lesions.
A computer-generated mathematical model was developed based on clinical outcome modeling to estimate costs accrued during evaluation and treatment of suspicious mammographic lesions. Total costs were determined for evaluation and subsequent treatment of cancer when either SCB or NLB was used as the initial biopsy method. Cost was estimated by the cumulative work relative value units accrued. The risk of malignancy based on the Breast Imaging Reporting Data System (BIRADS) score and mammographic suspicion of ductal carcinoma in situ were varied to simulate common clinical scenarios.
Total cost accumulated during evaluation and subsequent surgical therapy (if required).
Evaluation of BIRADS 5 lesions (highly suggestive, risk of malignancy = 90%) resulted in equivalent relative value units for both techniques (SCB, 15.54; NLB, 15.47). Evaluation of lesions highly suspicious for ductal carcinoma in situ yielded similar total treatment relative value units (SCB, 11.49; NLB, 10.17). Only for evaluation of BIRADS 4 lesions (suspicious abnormality, risk of malignancy = 34%) was SCB more cost-effective than NLB (SCB, 7.65 vs. NLB, 15.66).
No difference in cost-benefit was found when lesions highly suggestive of malignancy (BIRADS 5) or those suspicious for ductal carcinoma in situ were evaluated initially with SCB vs. NLB, thereby disproving the hypothesis. Only for intermediate-risk lesions (BIRADS 4) did initial evaluation with SCB yield a greater cost savings than with NLB.
Archives of Surgery 10/2001; 136(9):990-4. · 4.24 Impact Factor
-
V. Khatri
[show abstract]
[hide abstract]
ABSTRACT: Summary form only given. The objective of this research is to develop a spatiotemporal semantic model that can be used for conceptual database design and information integration of geospatial datasets. The authors' research methodology includes developing a theoretical framework, demonstrating the practicality of the framework using prototypes and evaluating the framework using a case study and an experiment. The authors define an annotation-based approach, a generic methodology that can be applied to any conventional semantic model to translate it into a spatiotemporal semantic model. The authors have applied their annotation-based approach to the unifying semantic model (USM), a conventional conceptual model to propose the spatiotemporal-unifying semantic model (ST-USM). They have defined the annotation syntax in Backus Naur form (BNF) and have formally defined spatiotemporal semantics using first order logic. Using ST-USM, they are developing a database design tool that, helps define a straightforward to use comprehensive methodology to capture spatiotemporal semantics for database applications
Management of Engineering and Technology, 2001. PICMET '01. Portland International Conference on; 02/2001
-
[show abstract]
[hide abstract]
ABSTRACT: An EMTP based study of a CIGRE benchmark based HVDC system
operating with weak AC systems is carried out. The modelled system
provides a starting point for (a) educators teaching HVDC transmission
courses, and (b) for utility planners to develop their own low-cost
dedicated digital simulators for training purposes. In this paper,
modelling details of the AC-DC system, DC converters and controls are
presented. To validate the control schemes presented, the HVDC system is
tested under AC-DC fault conditions. Results obtained from an EMTP-based
study under these fault conditions are also presented in this
paper
Power Electronics, Drives and Energy Systems for Industrial Growth, 1996., Proceedings of the 1996 International Conference on; 02/1996
-
[show abstract]
[hide abstract]
ABSTRACT: Results are presented from an EMTP study on the operational
behavior of the gate firing unit (GFU) of an HVDC converter system
operating with a weak AC power system. A voltage controlled oscillator
(VCO) is used in conjunction with a phase locked loop (PLL) in the GFU
of the HVDC converter system to achieve a satisfactory transient
performance
Electrical and Computer Engineering, 1994. Conference Proceedings. 1994 Canadian Conference on; 10/1994
-
[show abstract]
[hide abstract]
ABSTRACT: The study of the transient performance of an HVDC power converter
using EMTP requires detailed modelling of the controls and power system
elements. Furthermore, owing to the complexities associated with EMTP,
considerable care has to be exercised during simulation. These
requirements take on added importance particularly when the HVDC power
converter is operated with a weak AC power system. This paper looks at
the impact of the gate firing unit, the valve snubber in the power
converter model and the initialization technique when operating a
rectifier with a weak AC power system
Computers in Power Electronics, 1994., IEEE 4th Workshop on; 09/1994
-
[show abstract]
[hide abstract]
ABSTRACT: Prior research has shown that the effect of information systems (IS) domain knowledge and application domain knowledge on problem solving is contingent on task type (Khatri et al. 2006). We build on this study by engaging in an in-depth analysis of how both these types of knowledge influence one type of task referred to as “schema-based problem solving” task. Our theoretical analysis is based on the fact that conceptual schema understanding is a well-structured problem area and that, in such a setting, participants engage in depth-first rather than the breadth-first search that is evident in the more-frequently studied ill-structured problem areas. We used protocol analysis to explore the search process in the context of varying levels of both IS and application domain knowledge. We found that knowledge of the IS and application domains result in similar effects on the search process: both high IS knowledge and familiarity with the application domain result in deeper (more focused) search.
-
[show abstract]
[hide abstract]
ABSTRACT: Although information systems (IS) problem solving involves knowledge of both the IS and application domains, little attention has been paid to the role of application domain knowledge. In this study, which is set in the context of conceptual modeling, we examine the effects of both IS and application domain knowledge on different types of schema understanding tasks: syntactic and semantic comprehension tasks and schema-based problem-solving tasks. Our thesis was that while IS domain knowledge is important in solving all such tasks, the role of application domain knowledge is contingent upon the type of understanding task under investigation. We use the theory of cognitive fit to establish theoretical differences in the role of application domain knowledge among the different types of schema understanding tasks. We hypothesize that application domain knowledge does not influence the solution of syntactic and semantic comprehension tasks for which cognitive fit exists, but does influence the solution of schema-based problem-solving tasks for which cognitive fit does not exist. To assess performance on different types of conceptual schema understanding tasks, we conducted a laboratory experiment in which participants with high- and low-IS domain knowledge responded to two equivalent conceptual schemas that represented high and low levels of application knowledge (familiar and unfamiliar application domains). As expected, we found that IS domain knowledge is important in the solution of all types of conceptual schema understanding tasks in both familiar and unfamiliar applications domains, and that the effect of application domain knowledge is contingent on task type. Our findings for the EER model were similar to those for the ER model. Given the differential effects of application domain knowledge on different types of tasks, this study highlights the importance of considering more than one application domain in designing future studies on conceptual modeling.
