Yossef Kabessa

Simultaneous quantification of the fluorescent responses of an ensemble of bacterial sensors

Bacterial bioreporters are genetically engineered microbial strains capable of detecting specific chemicals, groups of chemicals or global biological effects such as toxicity or genotoxicity. A scheme for simultaneous selective detection of the fluorescent signals emitted by a bacterial biosensor array, able to detect four different types of toxicants, using a single photodetector (photomultiplier) is presented. The underlying principle of the scheme is to convert the spatially distributed signals from all the elements in the array to temporally distributed frequency multiplexed signals at the output of the photodetector. Experimental proof of this concept is demonstrated in a four-channel system, in which low power (a few tens of picowatts) fluorescent signals produced by the bacterial sensors are measured, while maintaining a wide dynamic range of detection (more than 3 orders of magnitude). Simultaneous monitoring of concentrations down to a few mg/l of different chemicals in a liquid sample is demonstrated.

Remote detection of buried landmines using a bacterial sensor

VOLUME 35 NUMBER 4 APRIL 2017 NATURE BIOTECHNOLOGY with a novel mode of action is approved for marketing? We submit that three decades of soliciting public engagement has not improved the public acceptance cited by advocates as a justification for the efforts, and that subordinating evidence-based policy making to emotional or political calculations has neither increased public acceptance nor encouraged innovation. We would prefer to heed the caveat of Barbara Keating-Edh, who testified before the National Biotechnology Policy Board in 1991, representing the consumer group Consumer Alert: “For obvious reasons, the consumer views the technologies that are most regulated to be the least safe ones. Heavy involvement by government, no matter how well intended, inevitably sends the wrong signals. Rather than ensuring confidence, it raises suspicion and doubt” [emphasis in original]11. We believe that the current excessive and unscientific regulation at the US Environmental Protection Agency (EPA), USDA and FDA (and other agencies) erodes both public understanding and trust, and exacerbates skepticism about the safety of

Curved space nanophotonics inspired by general relativity

We present nanophotonic structures in three dimensions inspired by General Relativity concepts, enabling control over the light dynamics: the group and phase velocities together with the spatial modes structure, suggesting implications to enhancing light-matter interaction.

Suppression of optical damage in electro-optical modulator using potassium lithium tantalate niobate

Suppression of optical damage in a KLTN based electrooptical modulator operated with 30 W/cm2 light beam at λ=445 nm is demonstrated. The modulator is driven by bipolar voltage which prevents the induced space-charge from accumulating.

Electro-optical modulation with immunity to optical damage by bipolar operation in potassium lithium tantalate niobate

A method for suppressing the formation of optical damage in quadratic electrooptic devices operated at short wavelengths is presented. Formation of optical damage is attributed to the generation of a trapped space charge induced by photoionization of impurity ions by the propagating beam. It is shown that in potassium lithium tantalate niobate where the electrooptic effect is quadratic, operating the electrooptic device by a bipolar driving voltage prevents the space charge from accumulating, which inhibits the formation of the optical damage. A 6 hours continuous operation of electrooptic modulator for a 30 W/cm(2) at λ = 445 nm input beam is demonstrated.