title: Lagunamides A and B: Cytotoxic and antimalarial Cyclodepsipeptides from the Marine cyanobacterium Lyngbya majuscule

authors: Tripathi, Ashootosh

subjects: chemistry

abstract: Lagunamides A (1) and B (2) are new cyclic depsipeptides isolated from the marine cyanobacterium Lyngbya majuscula obtained from Pulau Hantu Besar, Singapore. The planar structural characterization of these molecules was achieved by extensive spectroscopic analysis, including 2D NMR experiments. In addition to Marfey’s method and 3JH−H coupling constant values, a modified method based on Mosher’s reagents and analysis using LC-MS was deployed for the determination of the absolute configuration. Lagunamides A and B displayed significant antimalarial properties, with IC₅₀ values of 0.19 and 0.91 μM, respectively, when tested against Plasmodium falciparum. Lagunamides A and B also possessed potent cytotoxic activity against P388 murine leukemia cell lines, with IC₅₀  values of 6.4 and 20.5 nM, respectively. Furthermore, these cyanobacterial compounds exhibited moderate antiswarming activities when tested against Pseudomonas aeruginosa PA01.

text: Lagunamides A and B: Cytotoxic and antimalarial Cyclodepsipeptides from the Marine cyanobacterium Lyngbya majuscule Lagunamides A (1) and B (2) are new cyclic depsipeptides isolated from the marine cyanobacterium Lyngbya majuscula obtained from Pulau Hantu Besar, Singapore. The planar structural characterization of these molecules was achieved by extensive spectroscopic analysis, including 2D NMR experiments. In addition to Marfey’s method and 3JH−H coupling constant values, a modified method based on Mosher’s reagents and analysis using LC-MS was deployed for the determination of the absolute configuration. Lagunamides A and B displayed significant antimalarial properties, with IC₅₀ values of 0.19 and 0.91 μM, respectively, when tested against Plasmodium falciparum. Lagunamides A and B also possessed potent cytotoxic activity against P388 murine leukemia cell lines, with IC₅₀  values of 6.4 and 20.5 nM, respectively. Furthermore, these cyanobacterial compounds exhibited moderate antiswarming activities when tested against Pseudomonas aeruginosa PA01.

year: 2010

title: Illumination waveform optimization for time-of-flight range imaging cameras

authors: Payne, Andrew D.

subjects: time of flight

abstract: Time-of-flight range imaging sensors acquire an image of a scene, where in addition to standard intensity information, the range (or distance) is also measured concurrently by each pixel. Range is measured using a correlation technique, where an amplitude modulated light source illuminates the scene and the reflected light is sampled by a gain modulated image sensor. Typically the illumination source and image sensor are amplitude modulated with square waves, leading to a range measurement linearity error caused by aliased harmonic components within the correlation waveform. A simple method to improve measurement linearity by reducing the duty cycle of the illumination waveform to suppress problematic aliased harmonic components is demonstrated. If the total optical power is kept constant, the measured correlation waveform amplitude also increases at these reduced illumination duty cycles. Measurement performance is evaluated over a range of illumination duty cycles, both for a standard range imaging camera configuration, and also using a more complicated phase encoding method that is designed to cancel aliased harmonics during the sampling process. The standard configuration benefits from improved measurement linearity for illumination duty cycles around 30%, while the measured amplitude, hence range precision, is increased for both methods as the duty cycle is reduced below 50% (while maintaining constant optical power).

text: Illumination waveform optimization for time-of-flight range imaging cameras Time-of-flight range imaging sensors acquire an image of a scene, where in addition to standard intensity information, the range (or distance) is also measured concurrently by each pixel. Range is measured using a correlation technique, where an amplitude modulated light source illuminates the scene and the reflected light is sampled by a gain modulated image sensor. Typically the illumination source and image sensor are amplitude modulated with square waves, leading to a range measurement linearity error caused by aliased harmonic components within the correlation waveform. A simple method to improve measurement linearity by reducing the duty cycle of the illumination waveform to suppress problematic aliased harmonic components is demonstrated. If the total optical power is kept constant, the measured correlation waveform amplitude also increases at these reduced illumination duty cycles. Measurement performance is evaluated over a range of illumination duty cycles, both for a standard range imaging camera configuration, and also using a more complicated phase encoding method that is designed to cancel aliased harmonics during the sampling process. The standard configuration benefits from improved measurement linearity for illumination duty cycles around 30%, while the measured amplitude, hence range precision, is increased for both methods as the duty cycle is reduced below 50% (while maintaining constant optical power).

year: 2011

title: In defence of mātauranga Māori: A response to the 'seven academics'

authors: Waitoki, Waikaremoana

abstract: On 28 July 2021, a group of academics from the University of Auckland published a letter in the Listener, a well-known, non-academic magazine. The letter writers expressed their moral outrage that the Government’s NCEA curriculum working group proposed that science would be taught to Māori students along with its colonising history.

text: In defence of mātauranga Māori: A response to the 'seven academics' On 28 July 2021, a group of academics from the University of Auckland published a letter in the Listener, a well-known, non-academic magazine. The letter writers expressed their moral outrage that the Government’s NCEA curriculum working group proposed that science would be taught to Māori students along with its colonising history.

year: 2022-04-01