Getting the right picture, or getting the picture right?

first_imgDear Editor,Getting the right picture, or getting the picture right? In response to WPA’s criticisms of the high-handed manner in which WPA Executive Member David Hinds was booted out of the pages of the State-owned Guyana Chronicle as a fifth columnist, a picture of President David Granger and WPA’s co-leader Rupert Roopnaraine embracing each other graced the pages of the Chronicle, along with a plea by Roopnaraine for the WPA to remain within the APNU. It was obvious that the Chronicle’s picture was worth a thousand words.The article featured Roopnaraine’s appeal to the WPA not to break away from the APNU and the governing coalition of the APNU/AFC. The WPA is an integral part of the APNU. It is interesting to note that presidential candidate Granger, in the 2015 elections, campaigned with a picture of Moses Nagamootoo and himself as a symbol of racial unity. What exactly was the picture of the President and Roopnaraine projecting in the current situation?After running with David Granger in the 2011 elections, Roopnaraine and the WPA cleared the way for Moses Nagamootoo to become the Prime Minister in 2015. At the press conference announcing the signing of the Cummingsburg Accord, when asked by a reporter if the WPA was not concerned that it had lost its place and was now a junior partner, Tacuma Ogunseye responded that, for the WPA, the national interest was more important than the party’s interest, and that was a price that the WPA was willing to pay to advance the country.As was pointed out in Ogunseye’s account of events in relation to the 2011 elections, the PNCR wanted an Indian prime ministerial candidate to run with presidential candidate Granger. This was to symbolize racial outreach within the APNU platform.The abrupt termination of the Walter Rodney Commission of Inquiry (WRCOI) posed a serious challenge to the WPA very early in the life of the new Government. Roopnaraine’s silence on this matter exposed the WPA to ridicule both at home and abroad. At the same time, it proved to President Granger that he could rely on Roopnaraine to subvert the will of the WPA.The manner in which Roopnaraine was assigned the Ministry of Education without any consultations whatsoever with the WPA revealed a single-mindedness of President Granger in party politics. Roopnaraine’s assignment as Education Minister was arbitrarily decided. His subsequent removal from the ministry and reassignment to another ministry in the most bizarre of manner displayed a contempt for both Roopnaraine and the WPA that would have made the Mona Lisa weep.The debate surrounding the posturing of Roopnaraine is now a source of great concern for the WPA. There is an obvious and glaring problem when Tacuma Ogunseye put the possibility of the WPA withdrawing from the APNU coalition if it is not treated with some respect, only to be contradicted by Roopnaraine. There was no explanation whatsoever on the part of Dr Roopnaraine on why the WPA must be treated in such a disgraceful manner and remain within APNU.The Chronicle picture portrays a message of racial unity, disregarding three years of non-consultation with the WPA on serious matters of Government policies, placing it in a delicate position were it to attempt to discipline Roopnaraine.Any attempt by the WPA to deal with Roopnaraine’s misguided role as it affects the well-being of the WPA may be open to exploitation by opponents of the WPA. These opponents will seek to portray it as an attempt by the African members of the party to rid itself of one of its Indian leaders, a possibility that has forced the WPA to tread carefully on this matter. But failure to resolve this issue will only continue to do more damage to the WPA. The party will have to trust the public’s opinion as to whether it has acted correctly on this matter, and will have to deal with it in a transparent manner, so that the right image can be projected.Sincerely,Rohit KanhaiMember of Working People’s Alliance Overseas Associates (WPAOA)last_img read more

Physicists Ponder Atoms Without Nuclei

first_imgThis illustration ashows the absolute value of the real part of the two-electron wave function for the H-initial state (a) before and (b) after an attosecond full-cycle pulse with a half-cycle momentum transfer equal to 10 atomic units and pulse duration equal to 0.6 atomic units. The arrow in (b) points in the direction in which the wavepacket is displaced with respect to the nucleus and the CM denotes the center of mass of the wavepacket. The small cut in the wavepacket in (b) is due to the electron-electron repulsion in the continuum. Image Credit: Darko Dimitrovski. Explore further What to call such a system is not yet an urgent matter, since, for now, an atom without a nucleus is just a hypothetical concept. But physicists John Briggs and Darko Dimitrovski from the University of Freiburg in Germany have recently described how such an atom might be created with the use of an attosecond laser. Capable of generating pulses that last just one billionth of a billionth of a second (10-18 seconds), an attosecond laser could possibly “detach” the electrons from an atom and – keeping their shape largely intact – remove them from being centered around the nucleus.“I would not call it an ‘atom,’” Briggs told PhysOrg.com. “Maybe an ‘atom without a nucleus’ or a ‘filleted atom.’ However, one should not forget that when several electrons are involved, once the nucleus is away, the electrons will repel themselves, and the ‘atom’ will be destroyed. Nevertheless, coincident detection of the electrons should allow reconstruction of the initial wavepacket.” Briggs said that he is not aware of the idea of an atom without a nucleus being proposed before. But such a thing could potentially be created because the duration of an attosecond laser pulse is much shorter than the orbital time of an atom’s ground-state electrons. In a hydrogen atom, for example, an electron takes about 24 attoseconds to orbit the nucleus. Besides being short, the attosecond laser pulse must also be very strong, with an electric field equal to or greater than the nuclear field experienced by a bound electron.The researchers propose that a single short (10-attosecond), strong (1018-watt) laser pulse interacting coherently with the ground electrons could be used to remove all the electrons from an atom, completely ionizing the atom. In the first half-cycle of a pulse, several atomic units of momentum would be transferred, causing the electrons to accelerate away from the nucleus without changing the form of their initial wavefunction.Normally, an electron wavepacket that leaves an atom spreads out and loses its shape, and the electrons quickly repel each other and fly apart. However, due to the extremely short attosecond pulse, the wavepacket has almost no time to spread. Although a single half-cycle pulse can produce this wavepacket, electromagnetic theory shows that a half-cycle alone cannot be produced. So the researchers use the second half-cycle pulse to stop the electron wavepacket from moving away from the nucleus, producing a stationary atomic electron cloud spatially distant from its nucleus. Instead of being centered around the original nucleus, the wavepacket has shifted and is centered around the pulse’s mean momentum. The researchers explain that this scheme could apply not only to single- or multi-electron atoms, but also to molecules. The greatest challenge, of course, is in building an attosecond laser with such a short, strong pulse. A sufficient attosecond laser – once it exists – could enable researchers to test Briggs and Dimitrovski’s proposal. Using different half-pulses, researchers could create atoms without nuclei, as well as slow down electron wavepackets for extraction by detector fields. “We conceived this as a ‘sexy’ little experiment,” Briggs explained. “However, the real message of the paper is that one should be able to fully ionize an atom or molecule (or even clusters of atoms or plasmas) and then control and manipulate, by further half-cycle momentum kicks, the state of the continuum electron wavepacket. The possibility of observing rather directly the spatial bound-state atomic wavefunction moving nucleus-free, essentially undistorted, is just one example of this general technique that the development of strong attosecond lasers will make realizable.”More information: Briggs, John S.; and Dimitrovski, Darko. “Ionization in attosecond pulses: creating atoms without nuclei?” New Journal of Physics 10 (2008) 025013.Copyright 2008 PhysOrg.com. All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.com. This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.center_img You might remember learning in sixth grade science class that isotopes are atoms that have lost or gained a few neutrons, and ions are atoms that have lost or gained a few electrons. But what about an atom that has lost its entire nucleus – when essentially all that remains are the electrons whizzing around in their defined orbits? What happens when you explode a chemical bond? Citation: Physicists Ponder Atoms Without Nuclei (2008, March 19) retrieved 18 August 2019 from https://phys.org/news/2008-03-physicists-ponder-atoms-nuclei.htmllast_img read more