This paper proposes iPTT, a peer-to-peer Push-toTalk (PTT) service for Voice over IP (VoIP). In iPTT, a distributed and mobile-operator independent network architecture is presented to accelerate the deployment of the PTT service. Based on the proposed architecture, the message flows for call establishment/teardown are designed to show the feasibility of iPTT. Also, we propose two mechanisms fo...

Two methods of extending measured room impulse responses below their noise floor and beyond their measured duration are presented. Both methods extract frequency-dependent reverberation energy decay rates, equalization levels, and noise floor levels, and subsequently extrapolate the reverberation decay towards silence. The first method crossfades impulse response frequency bands with a late-fie...

Despite regular disinfection and decontamination of the hospital floors and surfaces, resistant pathogens from the hospital surfaces and their transmission to humans have been reported recently. The resistance of pathogens to the disinfectant agents or failed disinfection techniques have put the routine floor and non-critical surface disinfection done in hospitals into question with regard to t...

In acid-impacted forests, decreased soil pH and calcium (Ca) availability have the potential to influence biotic and abiotic controls on carbon (C) and nitrogen (N) cycling. We investigated the effects of liming on above- and belowground C and N pools and fluxes 19 years after lime addition to the Woods Lake Watershed, Adirondack Park, New York, USA. Soil pH and exchangeable Ca remained elevate...

Experience in the management of 77 isolated orbital floor fractures is presented. The transconjunctival approach was used exclusively to access the orbital floor and lyophilized dura and cartilage were used to reconstruct the floor, when indicated. Follow-up for an average of 36 months showed excellent cosmetic and functional results. A 20% complication rate was noted, which compares favorably ...

In this paper, we define a stopping set of turbo codes with the iterative decoding in the binary erasure channel. Based on the stopping set analysis, we study the block and bit erasure probabilities of turbo codes and the performance degradation of the iterative decoding against the maximum-likelihood decoding. The error floor performance of turbo codes with the iterative decoding is dominated ...