We present a new approach for determining a time-optimal trajectory for a robot manipulator with actuator torque bounds. We find an approximation to a globally optimal trajectory which passes between two configurations will avoiding obstacles. Our algorithm accomplishes this by by dynamically generating and searching a finite graph. Our algorithm is guaranted to produce a trajectory that performs within a user-specified factor of a time-optimal safe trajectory.
ABSTRACT Previous studies with Salmonella enterica serovar Typhimurium LT2 demonstrated that transcriptional activation of the prpBCDE operon requires the function of transcription factor PrpR, sigma-54, and IHF. In this study, we found that transcription from the prpBCDE and prpR promoters was down-regulated by the addition of glucose or glycerol, indicating that these genes may be regulated by the cyclic AMP (cAMP)-cAMP receptor protein (CRP) complex. Targeted mutagenesis of a putative CRP-binding site in the promoter region between prpR and prpBCDE suggested that these genes are under the control of CRP. Furthermore, cells with defects in cya or crp exhibited reduced transcriptional activation of prpR and prpBCDE in Escherichia coli . These results demonstrate that propionate metabolism is subject to catabolite repression by the global transcriptional regulator CRP and that this regulation is effected through control of both the regulator gene prpR and the prpBCDE operon itself. The unique properties of the regulation of these two divergent promoters may have important implications for mechanisms of CRP-dependent catabolite repression acting in conjunction with a member of the sigma-54 family of transcriptional activators.
Memristor, the missing fourth passive circuit element predicted forty years ago by Chua was recognized as a nanoscale device in 2008 by researchers of a H. P. Laboratory. Recently the notion of memristive systems was extended to capacitive and inductive elements, namely, memcapacitor and meminductor whose properties depend on the state and history of the system. In this paper, we use fractional calculus to generalize and provide a mathematical paradigm for describing the behavior of such elements with memory. In this framework, we extend Ohm's law to the generalized Ohm's law and prove it.
Urinary bladder cystitis occurs in patients receiving radiation therapy for pelvic tumors. Radiation-induced formation of superoxide radicals is believed to damage the urothelium, exposing the underlying bladder smooth muscle to urine, culminating in nerve irritation and muscle dysfunction. We tested whether overexpression of MnSOD could decrease superoxide levels and protect the bladder from radiation damage. Pelvic irradiation led to sloughing of urothelial umbrella cells, with decreased transepithelial resistance, increased water and urea permeabilities, and increased expression of inducible nitric oxide synthase. Six months after irradiation, cystometrograms showed elevated intravesical pressures and prolonged voiding patterns. However, urothelia transfected with the MnSOD transgene recovered from radiation injury more rapidly, and detrusor function was much closer to that of control bladders than irradiated bladders without the transgene. We conclude that MnSOD gene therapy is protective, which could lead to its use in mitigating radiation cystitis and preventing dysfunction of the urinary bladder.
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With an estimated 4.6 billion units in use, mobile phones have already become the most popular computing device in human history. Their portability and communication capabilities may revolutionize how people do their daily work and interact with other people in ways PCs have done during the past 30 years. Despite decades of experiences in creating modern WIMP (windows, icons, mouse, pointer) interfaces, our knowledge in building effective mobile interfaces is still limited, especially for emerging interaction modalities that are only available on mobile devices. This dissertation explores how emerging sensors on a mobile phone, such as the built-in camera, the microphone, the touch sensor and the GPS module can be leveraged to make everyday interactions easier and more efficient. We present studies and models to quantify the capabilities of these sensing channels, and show how effective interfaces in text entry, gaming, and CSCW can be built on mobile phones. The first such technology is TinyMotion. TinyMotion detects the movements of a mobile phone in real time by analyzing image sequences captured by its built-in camera, providing a usable analog pointing channel to existing mobile phone users. We quantified TinyMotion's human performance as a basic input control sensor. We found target acquisition tasks via TinyMotion follow Fitts' law, and Fitts' law parameters can be used for TinyMotion-based pointing performance measurements. We show that using camera phone as a handwriting capture device and performing large vocabulary, multilingual real time handwriting recognition on the mobile phone are feasible. Based on experiences and lessons learned from TinyMotion, this dissertation also introduces SHRIMP (Small Handheld Rapid Input with Motion and Prediction), a predictive mobile text input method runs on camera phones equipped with a standard 12-key keypad. SHRIMP maintains the speed advantage of Dictionary-Based Disambiguation (DBD) driven predictive text input while enabling the user to overcome collision and OOV problems seamlessly without explicit mode switching. Then, FingerSense is presented as another example of perceptual interface to enhance the expressiveness of physical buttons on space-constrained mobile devices. This dissertation also introduces a context-aware system named GLAZE (Generalized Location Aware ModelZ for End-users). GLAZE allows average user without any programming experiences, to create everyday location-aware applications directly on their mobile phones. Last, this thesis describes the design, implementation and evaluation of Event Maps, a web-based calendaring system targeted at improving the experience of attending and organizing large, multi-track conferences on both desktop computers and mobile devices. Event Maps has been successfully deployed in multiple large, real world conferences.
Fixturing is a fundamental problem in mechanical assembly. Usually, two and a half dimensional objects can be fixtured in many different ways using a fixture vice, especially if pegs of different radii are available. The authors present an algorithm which enumerates all force closure fixture vice configurations and corresponding object poses. Automatic fixture design algorithms are essential for planning because optimal fixturing selections for multiple operations requires examining all of the valid configurations. The algorithm runs in O(A) time, where A is the number of configurations which simultaneously contact the object.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
