Abstract: In one embodiment, a method, by one or more computing systems, includes determining, based on frames captured by a camera, a plurality of participants are located in an environment, locating, within a first frame, a first body region of a first participant of the plurality of participants, detecting, at a first time, appearance information of the first body region of the first participant, calculating, using one or more machine-learning models, a confidence score corresponding to a match between the appearance information of the first participant at the first time and one or more profiles of pre-registered participants, updating, using the one or more machine-learning models, the confidence score based on one or more additional appearance information detected within additional frames, determining whether the updated confidence score is above a predetermined threshold, and in response to determining the updated confidence score is above the predetermined threshold, authenticating the first participant.

Abstract: In one embodiment, a method includes an intelligent communication device detecting that a person is visible to a camera of the device, determining a first biometric characteristic of the person discernable by the device, associating the first biometric characteristic with a user identifier unique to the person, determining, while the person is identifiable based on the first biometric characteristic, a second biometric characteristic of the person discernable by the device, and associating the second biometric characteristic with the user identifier.

Abstract: In one embodiment, a method includes an intelligent communication device detecting that a person is visible to a camera of the device, determining a first biometric characteristic of the person discernable by the device, associating the first biometric characteristic with a user identifier unique to the person, determining, while the person is identifiable based on the first biometric characteristic, a second biometric characteristic of the person discernable by the device, and associating the second biometric characteristic with the user identifier.

Abstract: In one embodiment, a method includes receiving light signals from an interaction device, where the captured light signals are processed into one or more images that include illumination patterns associated with one or more objects, accessing light signals only within a particular spectrum range, detecting one or more tracking patterns from the accessed light signals within the particular spectrum range, where each of the one or more tracking patterns indicates a particular portion of a first object, and where the first object is a part of the one or more objects, determining one or more characteristics of the first object based on the detected one or more tracking patterns, and sending one or more content items and instructions causing a projector to project the one or more content items on the first object to the interaction device.

Abstract: A computer has a processor and nontransitory memory. The computer receives a list of search keywords to propose to a search engine. For search keywords that are too infrequently used to have historical data to estimate keyword performance, the computer computes linguistic similarity between the sparse-data keyword to other keywords that have sufficient historical keyword performance data to permit a statistically sound estimate for keyword performance. The estimates are submitted to a search engine, and updated by grouping the sparse-data keywords into groups, including at least a high-performing group and a low-performing group, and reallocating budget from the keywords of the low-performing group to keywords of the high-performing group, by reducing estimates for keywords of the low-performing group and increasing estimates of keywords of the high-performing group.

Abstract: Phosphoric acid, essentially free from impurities, is prepared by reacting aqueous hydrofluoric acid with phosphate in particles of calcium bearing phosphate rock to form a calcium fluoride pseudomorph solid from which filter-grade phosphoric acid is separated. By reacting the pseudomorph solid with sulfuric acid and thermally treating the reaction product, the HF can be liberated and recycled back to the reaction step of the process. All of the impurities from the phosphate rock are contained in the resulting CaSO4.

Abstract: Nascent hydrogen and nascent oxygen are used to convert calcium sulfate and silicon dioxide to calcium silicate and sulfur dioxide.

Abstract: 1. Compounds of the general formula ##EQU1## in which R.sup.2 is selected from the group consisting of ##EQU2## 6. A process for the preparation of compounds of the general formula in which R.sup.2 is as defined in claim 1, which comprises nitrating, with a mixture of sulfuric and nitric acids, diols of the general formula ##EQU3## in which R.sup.2 is as defined in claim 1.