Two-Photon Total Annihilation of Molecular Positronium

The rate for complete two-photon annihilation of molecular positronium Ps$_{2}$ is reported. This decay channel involves a four-body collision among the fermions forming Ps$_{2}$, and two photons of 1.022 MeV, each, as the final state. The quantum electrodynamics result for the rate of this process is found to be $\Gamma_{Ps_{2} \rightarrow \gamma\gamma}$ = 9.0 $\times 10^{-12}$ s$^{-1}$. This decay channel completes the most comprehensive decay chart for Ps$_{2}$ up to date.Comment: 4 pages, 2figures and 1 tabl

Contaminated water treatment

Method and system for processing of a liquid ("contaminant liquid") containing water and containing urine and/or other contaminants in a two step process. Urine, or a contaminated liquid similar to and/or containing urine and thus having a relatively high salt and urea content is passed through an activated carbon filter to provide a resulting liquid, to remove most of the organic molecules. The resulting liquid is passed through a semipermeable membrane from a membrane first side to a membrane second side, where a fortified drink having a lower water concentration (higher osmotic potential) than the resulting liquid is positioned. Osmotic pressure differential causes the water, but not most of the remaining inorganic (salts) contaminant(s) to pass through the membrane to the fortified drink. Optionally, the resulting liquid is allowed to precipitate additional organic molecules before passage through the membrane

INTERNATIONAL PHONETIC ALPHABET (IPA) FRONT VOWEL SOUND RECOGNITION OF BEGINNER FOREIGN LEARNERS

English, as a second language (L2) learning and teaching, is one of the booming global industries. The Philippines is recognised as a quality provider of English language learning where non-native English speakers student come to study. This paper investigated the front vowel sound recognition of beginner foreign learners based on the International Phonetic Alphabet (IPA). Front vowel recognition was assessed in terms of its influence on foreign learners’ sound production and recognition. The study employed a survey research design to selected Taiwanese and Japanese respondents, identified their common errors as beginner foreign language learners and determined if their sound production is influenced by their sound recognition. This paper argues that sound recognition leads to good communication skills among beginner foreign language learners and sufficient knowledge in recognising the front vowel sound leads to better comprehensible conversation. Findings of the study revealed that vowel sounds are very difficult to recognise by beginner foreign language learners. Both foreign learner groups experienced hard time recognising front vowel sounds which, fundamentally influenced sound production. Sound recognitions vary between Taiwanese and Japanese learners. Foreign beginner learners undergo difficulties in recognising front vowel sounds thereby affect their word production. Only upon correct sound recognition can foreign learners attain correct word production. We recommend that appropriate teaching methods be employed to ensure correct sound recognition among foreign learners in the Philippine context. Teachers need to engage the learners in fun-filled and interactive instructions to develop the learners’ ability in recognising sounds. Only when a learner recognises and produces the sound correctly that comprehensible communication is achieved.  Article visualizations

Mesin Bor Otomatis Dengan Menggunakan Kamera Untuk Mendeteksi Koordinat Bor

This paper describes about automatic drilling machine used to drill pad and via in Printed Circuit Board (PCB). The automatic drilling machine used camera as the sensor to detect coordinates of pad and via in PCB. This system used several methods of image processing like threshold, grayscale, and fillrect to detect the pad and via coordinates. This processes result the pad and via coordinates in pixels, then, these coordinates would be converted to millimeters in order to perform the drilling process. The automatic drilling machine used two stepper motors to perform the movement of X-axis and Y-axis. The machine also used two DC motors for the movement of Z-axis and drilling motor. The movement of each axis was designed by using the thread of a screw in order to achieve the precision movement. Experiment results show that average errors of the X-axis and Y-axis movement are 0.275 mm and 0.283 mm respectively. The system also could detect correctly all pad and via in PCB