VT LEAGUE FINALS ACTION

first_imgThe inaugural VT league finals took place last weekend, with some exciting action in both the semi finals and grand finals in both the men’s and women’s division, with two matches heading to drop offs and another totaling an amazing 19 touchdowns. For all the action from the days play view the attached summary. Related Filesvt_league_finals_report-docvt_league1-jpglast_img

10 months agoMan Utd boss Mourinho: My 2 friends in the Premier League

first_imgMan Utd boss Mourinho: My 2 friends in the Premier Leagueby Paul Vegas10 months agoSend to a friendShare the loveManchester United boss Jose Mourinho says two of his fellow Portuguese are the Premier League managers who are closest to him.In an interview with Soccer AM, he revealed who his best pal is among the current crop of Premier League bosses. “Nuno (Espirito Santo) was my player so I have a relationship with him from before,” he said.”Marco (Silva at Everton) I have known for years and he’s a good guy too.”Former goalkeeper Nuno was at Porto for years in two separate spells, with Mourinho his boss from 2002-04.When asked if he ever had a night on the town with Nuno, Mourinho was a little more coy.”In spite of the fact that we are both now managers I think we have a thing that I was your manager and you were my player,” he added.”That’s nice for me. There is always that little thing in the relationship.” About the authorPaul VegasShare the loveHave your saylast_img read more

25 days agoEveryone will know ‘top class’ Man Utd youngster Garner – Fletcher

first_imgAbout the authorFreddie TaylorShare the loveHave your say Everyone will know ‘top class’ Man Utd youngster Garner – Fletcherby Freddie Taylor25 days agoSend to a friendShare the loveFormer Manchester United star Darren Fletcher believes that James Garner is one to watch from the club’s academy.Garner has received significant praise for his performances for the under-23 side so far this season.He is a goalscoring, box to box midfielder who has appeared a level above the others at the under-23 level.And Fletcher believes the 18-year-old is a huge talent who can go all the way.”People talk about the leaders and who is going to help them, which is an important side [to the argument], so it’s a difficult one but I’m sure as the season goes on you’re going to see more of James Garner because he’s top class,” Fletcher told BBC Radio 5 Live.”I’m surprised he’s not featured so far but by the end of the season I’m sure that people will know who he is without a doubt, if you don’t by now.” last_img read more

Canadian Human Rights Tribunal to revisit Air Canada retirement age issue

first_imgTORONTO – The Canadian Human Rights Tribunal will be revisiting the issue of whether Air Canada was wrong to force some pilots to retire at age 60.A decision publicly released on Friday says the tribunal will hold another hearing to determine whether the airline had the right to force 45 pilots to retire at an age it deemed to be the industry standard.The decision says the case originally had 97 complainants, but 52 of them will not have their retirement age scrutinized by the tribunal.The issue of retirement age for Air Canada pilots has come up both at the tribunal and in federal court numerous times in the past decade.Two cases with different complainants, but similar arguments, were ruled upon by the tribunal, reviewed in federal court, then ultimately dismissed by the Federal Court of Appeal.The tribunal says the 52 pilots whose retirement dates were covered by the previous cases will not be included in the new hearing, but says it will hear arguments from the remaining 45 whose retirement dates fall outside of the timeline covered by the other cases.A lawyer representing the majority of the pilots expects the new tribunal hearing will get underway in early 2018.Raymond Hall said he welcomed the latest development in the highly complex case.“We’ve been at it for 12 years,” he said Friday in an interview. “It’s no small thing.”The new tribunal hearing will unfold against the complicated backdrop of both the two past cases as well as changes in federal law.In 2011, as part of an omnibus bill, the then Conservative government passed a law forbidding federally regulated companies such as Air Canada to enforce a mandatory retirement age on its employees. The law went into effect in December 2012.Prior to that legislation, the issue of retirement age at Air Canada had been hotly contested on at least two occasions at the tribunal.The first case, named the Vilven/Kelly matter after its two plaintiffs, challenged Air Canada’s imposition of a mandatory retirement age of 60 for pilots forced to stop working between 2003 and 2005.Despite an initially favourable ruling from the tribunal, the case was challenged in federal court and ultimately quashed by the Court of Appeal.The second case, dubbed Thwaites/Adamson, involved 70 plaintiffs who retired between 2005 and 2009.That, too, received contradictory rulings from the tribunal and federal courts before ultimately being dismissed by the Court of Appeal.In both cases, Hall sought leave to bring the cases before the Supreme Court of Canada, but that leave was denied.The third and most recent group of complainants, referred to as Bailie et al, had retirement dates ranging from June 2004 to February 2012.Air Canada and the Air Canada Pilots Association, which represents the thousands of people who man aircraft for the country’s largest airline, had filed a motion to dismiss the Bailey complaint.Their primary rationale, according to the decision, was the fact that the issues at hand had been rehashed before in the two previous cases.Adjudicator David Thomas wrote in the decision that this held true for the 52 pilots who had retired before 2010, but that the 45 who retired after that date had not yet had a chance to air their grievances.While describing the possibility as improbable, he conceded that there may have been changes in the industry during those years that would make the forced retirement discriminatory on the basis of age.“While I am sympathetic to the respondents’ arguments that it is ‘highly improbable’ that a meaningful change to the material facts affecting the normal age of retirement occurred during the short period after Dec. 31, 2009 until the last Bailie complainant reached the age of 60 in February of 2012, I have not been provided with satisfactory information that there were no changes in the industry,” he wrote. “…it is not the role of the tribunal to speculate whether certain evidence may or may not exist. The tribunal has no investigatory powers and has no material evidence before it for the younger complainants. It is the right and the obligation of the parties to present that evidence to the tribunal in a quasi-judicial forum.”-Follow @mich_mcq on Twitterlast_img read more

BC Chamber of Commerce reports on the Budget 2019

first_imgThe BCCC shares the areas the Budget did not address issues identified by businesses;A commitment to a comprehensive review of the taxation system to make it fair and less cumbersome for businesses.A broad-based commitment to reduce the regulatory burden on businesses. VANCOUVER, B.C. – The BC Chamber of Commerce (BCCC) reports the Budget 2019 leaves business concerns to the side by falling short on addressing fundamental issues that affect B.C. businesses.The BCCC share there were some small wins in the budget, yet the budget failed to address key issues such as global tax competitiveness, reduced business confidence, and a slumping investment in BC businesses.“Our 2018 Collective Perspective Survey showed that confidence in the BC economy is declining in 50% of BC businesses.  “Current tax rates are hurting our ability to compete globally,” says Val Litwin, CEO of the BC Chamber of Commerce. This budget didn’t adequately address productivity or competitiveness in a way that will grow our economy, create meaningful employment, and generate the revenues we need to sustain a healthy prosperous province and country,” Litwin says. The BCCC shares the areas the Budget did deliver in areas significant to BC Businesses;Multiple funding mechanisms to ensure that high-speed internet access is Canada-wide by 2030, with $1.7 billion specifically earmarked for rural, remote and Northern communities.$631.2 million to expand Work-Integrated-Learning (WIL) programs, with a view to create up to 20,000 new WIL opportunities outside of STEM-related fields.$150 million to create new partnerships between government and industry to create up to 20,000 new WIL opportunities.Multiple funding mechanisms to enhance apprentice programs in skilled trades.$3 billion in tax incentives through the SR&ED tax incentive to support business research and development (R&D) in Canada. The program provides a 35-per-cent refundable tax credit to eligible small and medium-sized businesses.center_img A renewed commitment to eliminating inter-provincial trade barriers and mobility.Support for SMEs to find new export opportunities and expand Canada’s ability to diversify its trade.A clear strategy to move the Trans Mountain pipeline forward, given the significant investment made by Canadian taxpayers.Budget 2019 proposals the BCCC share, require more consideration and details before determining the impact on businesses;The Budget identified funding programs to develop “regulatory roadmaps” to address stakeholder issues and irritants. While these efforts align with the BC Chamber’s interest in reducing the regulatory burden on Canadian businesses, the Budget proposals, unfortunately, maintain a lacklustre, made-by-government solution to a made-by-government problem.The new Canadian Training Credit and EI Training Support Benefits to support the up-skilling and re-skilling of Canadians align with the BC Chamber’s recommendations. However, the potential impact on small businesses remains unclear. The BC Chamber needs more information and wants to see a commitment that business is consulted.The Budget offered little new information regarding the national pharmacare plan. The BC Chamber supports focusing on the 10% of Canadians that are uninsured or underinsured and also supports the value of bulk drug purchasing to help British Columbians manage costs.The BC Chamber supports the Global Talent Stream program but would like to see a commitment from the program to bring skilled immigrants to rural communities, where they are often most needed.The BC Chamber network will continue to engage with Federal representatives to prioritize restoring a competitive tax structure, reducing regulatory burdens, and increasing access to skilled labour as critical priorities to maintain prosperity for all British Columbians.last_img read more

13 killed in South Africa church collapse

first_imgJohannesburg: At least 13 people have died and many injured in South Africa after a wall collapsed at a Pentecostal church at the start of an Easter service, authorities said. The incident happened on Thursday night in the coastal province of KwaZulu-Natal and emergency medical services spokesperson Robert McKenzie linked the tragedy to heavy rainfall in the area, South Africa’s online news publication News24 reported. Authorities said 29 people were rushed to hospital after the collapse of the wall at the front of the Pentecostal Holiness Church and six of them were seriously injured. Provincial police spokesperson Colonel Thembeka Mbele said the area experienced a storm and heavy winds which are believed to have resulted in the incident. People were sleeping in the church when the brick wall collapsed, she added. Following the incident, a special prayer service was held in front of the church on Friday, according to local eNCA TV station.last_img read more

Eerie Easter

first_imgNearly a decade after the 26-year long civil war in Sri Lanka came to a long-awaited close, the people of the island nation were crudely jolted with a series of coordinated attacks on churches and luxury hotels on Easter Sunday. Other nationals killed in the dastardly attack include Indians, Japanese and of USA. In solidarity with Sri Lanka, other nations and world leaders extended their condolences the grieving nation. On a day of worship and cheer, memories of the civil war were wrenched back in a flash. Faraz Shauketaly, a prominent journalist, spoke about the Sri Lanka Civil War and its connection to Sunday’s attack, reiterating that in Sri Lanka, the ethnic conflict began approximately 40 years ago and finished 10 years ago. The 3-decade long war was perpetrated by mainly a group of terrorists who claimed to want independence in the northern part of Sri Lanka, is a tiny island, about 240 miles long and 140 miles wide. May 18, 2019, will mark the 10-year anniversary of the end of the nation’s civil war fought between the Sri Lanka government and its Sinhala Buddhist majority and the Tamil Tigers minority ethnic group. Warning of more attacks in Sri Lanka, US Secretary of State Mike Pompeo commented that the United States will keep fighting “radical Islamic terror” in the wake of the Sri Lanka attacks. This comment very easily labels the mishap with a colour and a community that is otherwise vulnerable on the global stage. These attacks come in line with notorious attacks on churches, the latest being the fire that ravaged Notre Dame. The leaders of Sri Lanka, however, showed remarkable grit and insisted that the national suffering must not become a political game.last_img read more

Libyan deputy industry minister shot dead

first_imgTripoli – Assailants gunned down a Libyan deputy minister overnight, officials said on Sunday, in the first killing of a government member since the 2011 overthrow of dictator Moamer Kadhafi.Deputy industry minister Hassan al-Droui was shot dead during a to his hometown of Sirte, east of Tripoli, which was also Kadhafi’s hometown, security and hospital officials said.And in another sign of the instability plaguing the country, the toll from tribal clashes in the southern town of Sebha rose to 27 dead, with another 72 people wounded in the unrest. “Hassan al-Droui, the deputy minister for industry, was killed by unknown attackers overnight, during a visit to his native city of Sirte,” a security official told AFP.“Unidentified gunmen sprayed bullets on Mr. Droui in central Sirte,” the official said on condition of anonymity.A medical official at the city’s Ibn Sina hospital said Droui had suffered multiple gunshot wounds.The Libyan government denounced a “cowardly criminal act” and said in a statement it would “spare no effort to track down the perpetrators and prosecute them.”Droui was a former member of the National Transitional Council, the political arm of the rebellion that brought an end to Kadhafi’s 42-year rule.He was appointed deputy minister for industry by the transitional government’s first premier, Abdelrahim al-Kib, and kept his job when Prime Minister Ali Zeidan took office.Sirte, which lies on the Mediterranean coast about 250 miles (400 kilometres) east of Tripoli, was the last regime bastion to fall into rebel hands in the 2011 uprising during which Kadhafi was killed.Since the collapse of Kadhafi’s autocratic regime, Libya has been plagued by sporadic violence, including a string of assassinations targeting top army and security officials and the brief abduction of Zeidan.Deadly tribal clashesThe number of casualties from clashes between rival tribes in the southern town of Sebha and nearby Murzuq and Al-Shati rose to 27 dead and 72 wounded, a government statement said on Sunday.Fighting broke out in the area on Saturday pitting gunmen from the Arab Awled Sleiman tribe against tribesmen from the Toubou minority.Local sources said the clashes were sparked by the death on Thursday of a militia chief linked to Awled Sleiman, adding that the tribe accused the Toubou of murdering him.The Toubou are black oasis farmers by tradition who also live in southern Libya, northern Chad and Niger, who have repeatedly said they were being marginalised.A previous toll from the town’s local council had said that 19 died in the fighting and another 27 wounded.Fresh fighting broke out in Sebha on Sunday morning, witnesses reported.But in the afternoon the streets appeared to be calm, they said, adding that troops and policemen reinforcements were deployed in the town.The government said in a statement it sent reinforcements to secure residential areas and strategic installations in Sebha and that a “committee of elders” was trying to end the unrest.The fighting was the worst between the rival tribes since they struck a ceasefire agreement in March 2012 following deadly battles that killed at least 150 people and wounded 400 others.The Toubous have long complained of marginalisation by Libyan society, while Arab tribes have accused the minority of employing foreign fighters, particularly from Chad.The tribal clashes in Sebha could have a knock-on effect on production at several nearby oilfields in the mostly-desert south.Libya is currently struggling with a months-long oil crisis, which erupted when security guards at key oil terminals in the east shut them down, accusing the authorities of corruption and demanding a more equitable distribution of oil revenues.Oil Minister Abdelbari al-Arusi said last month that lost production from the blockades had cost Libya about $9.0 billion (6.6 billion euros) in revenues.last_img read more

Valverde hails unbelievable Messi after 400th La Liga goal

first_imgBarcelona manager Ernesto Valverde believes Lionel Messi’s incredible statistics speak for themselves after he scored his 400th La Liga goalIn just 435 league games, Messi registered his 400th goal as Barcelona cruised to a comfortable 3-0 win over SD Eibar on Sunday with Luis Suarez netting the other two goals.“I think the figures speak for themselves,” Valverde told the club website.“We don’t know if anyone will ever get close to those statistics but he is unbelievable.”The victory at Camp Nou enabled Barcelona to maintain their lead in La Liga to five points from second-place Atletico Madrid after 19 games.FC Barcelona, Valencia CFMatch Preview: Barcelona vs Valencia Boro Tanchev – September 14, 2019 Is derby time in La Liga, as Barcelona welcomes Valencia to the Camp Nou Stadium tonight at 21:00 (CET).“We have finished the first half of the season,” continued Valverde.“We wanted to maintain the advantage we had over the teams that are chasing us and we have done that.“The game was a tough one, like all the games against Eibar. They always put you under pressure high up the field.“At the end of the day we were able to get around that and we are happy because we have reached the halfway point of the league season top of the table, after having some tricky moments so far.”The Catalan giants will next face Levante in the second leg of their last-16 Copa del Rey tie on Thursday, where they hope to overturn their 2-1 deficit at home.last_img read more

National Capitol Labor Day Concert

first_imgThe Labor Day Concert at the U.S. Capitol on Sept. 3. The concert is scheduled to begin at 8 p.m. on the West Front of the United States Capitol. The National Symphony Orchestra will play. The event is free and open to the public. Tickets are not required.last_img

There and back again Extending optical storage lifetime by retrieving photon echoes

first_img © 2014 Phys.org , Physical Review Letters “For this reason, research on quantum optical memories attracted a lot of attention,” Akimov told Phys.org. “Current investigations of photon echoes have concentrated primarily on atomic vapors and rare earth crystals with long storage times, which are crucial for implementation of robust light-matter interfaces. However,” he noted, “light-matter coupling is weaker in these systems, so operation speed is not as fast as it could be in semiconductors. For example,” he illustrated, “efficient optical excitation in atomic systems is possible with optical pulses longer than one nanosecond, which slow down the operation speed by three orders of magnitude as compared to our protocol – and for rare earth crystals the pulse duration should be even longer.”In contrast to classical storage, quantum memory forbids measurement of the optical field during saving and retrieving processes. “In other words,” Akimov said, “storage of non-classical quantum light – such as squeezed light or a single photon – should occur without knowing which optical fields have been stored and retrieved, because otherwise the quantum state would be irreversibly destroyed during the measurement procedure. However, our protocol allows quantum storage since transfer between optical excitation and spin excitation does not require state measurement.” In other words, the new protocol transfers a quantum superposition between optically coupled states (optical excitation) and the other pair of states coupled by a magnetic field (spin excitation). In this process no measurement takes place – just the transformation between different excitations.Regarding the quantum well, the researchers specifically concentrated on an n-doped CdTe/(Cd,Mg)Te quantum well where storage time increased from picoseconds to tens of nanoseconds. The structures were grown by Prof. Grzegorz Karczewski and Prof. Tomasz Wojtowiczin the Institute of Physics, Polish Academy of Sciences in Warsaw using molecular beam epitaxy. (CdTe/(Cd,Mg)Te is a cadmium telluride compound in which some of the cadmium is replaced by magnesium.) “The cadmium telluride semiconductor quantum well structure is a model proof-of-principle system for extending the photon echo delay,” Akimov told Phys.org. “In such two-dimensional structures, the carriers are confined in one direction; this results in well-defined spin-level system and clean selection rules for optical transitions. Secondly, n-type doping of barriers with donors provides excess electrons in the quantum well which, again, are responsible for long-lived spin excitations.”That said, while using cadmium telluride quantum wells enabled very clean experiments on the ensemble of trions to be performed because their optical transitions are well isolated spectrally, the researchers had to maintain weak optical pulse intensity to prevent interactions between weakly localized trions. “In order to increase the efficiency and to achieve longer delays for photon echoes it is necessary to try different type of semiconductor nanostructures which can be also based on other compounds.,’ Akimov explained. “One of such candidates is the ensemble of quantum dots where the electrons and holes are localized much more strongly in all three dimensions. This is in contrast to quantum wells where strong confinement is present only along one direction.”Finally, Akimov noted that in semiconductors there are two types of fundamental optical excitations: excitons (electron-hole pairs bound by Coulomb interactions) and trions – charged excitons consisting of an exciton bound with an excess electron or hole. “A trion is a three-particle complex, and after its decay there’s always an excess carrier left,” he explained. “In our case, we deal with excess electrons which possess spin 1/2. Therefore, in contrast to excitons, it is possible to save information about optical excitation in the spin of the excess electrons left after trion recombination. This transformation is only possible when an external magnetic field is applied, since it allows us to mix the electronic states in the proper way.” The most salient advantage of quantum well structures is that exciton and trion resonances are spectrally well separated – meaning that picosecond laser pulses let the researchers address only the optical transition from excess electron to trion.For all of these seemingly daunting challenges, the researchers’ key insight was to study photon echoes emitted by trions in semiconductor nanostructures subject to an external magnetic field – and by then using a transient four-wave mixing (FWM) technique to measure magnetic-field-induced long-term photon echoes, they were able to show that photon echoes can be retrieved from excess electron spin ensembles. (Transient four-wave mixing belongs to time-resolved coherent spectroscopy based on non-linear optics, whereby interactions between two or three optical pulses in medium produce fourth optical field in the signal) “We used ultrashort optical pulses with duration of about one picosecond,” Akimov explained, “because efficient optical excitation in semiconductors is possible on the order of 0.1-1ps.” In addition, he said, the experiments had to be performed at extremely low temperatures – about two degrees above absolute zero – in order to keep the system robust against interactions with phonons (collective excitations, similar to quasiparticles, in a periodic, elastic arrangement of atoms or molecules in condensed matter, such as solids and some liquids), as well as to suppress other relaxation mechanisms which could lead to irreversible dephasing of optical and spin excitations and thereby loss of coherence. “From an experimental point of view,” he added, “our primary challenge was combining four-wave mixing with ultrashort picosecond pulses and external magnetic fields at low temperatures.”The current study demonstrates that photon echoes can be retrieved from the spin system on the timescale of 10-100 ns. “However,” Akimov said, “this time delay is still too short for practical applications. In order to solve this problem we need to extend the decay time of spin excitations.” There are two possible reasons for decay of spin excitations: dephasing of spins and irreversible spin relaxation through decoherence – that is, due to interaction with the environment. “The first point can be addressed by means of spin resonance techniques using dynamic decoupling,” he explained, “which is an approach largely the same as photon echo but based on periodic excitation of the spin ensemble with microwave pulses which lead to spin echoes. In that way it will be possible to keep the spin ensemble of excess electrons free of dephasing, and timescales up to tens or even hundreds of microseconds may be achieved. However, irreversible spin relaxation is more difficult to solve – but there are several attempts to reduce hyperfine interaction between nuclear and electron spins. One of the solutions would be to use compounds with isotopes carrying zero nuclear spin. In this case storage times in the milliseconds can be available.”In fact, Akimov added that the scientists plan to investigate extending the timescale of photon echoes further into the microsecond and millisecond range. “We’ll test other nanostructures, such as quantum dots with strong trion localization, and will search for new materials with suppressed spin excitation decay. In addition,” he said, “we’ll use spin resonance techniques in order to eliminate spin dephasing in the ensemble of excess electrons.”Akimov also mentioned applications beyond optical memory. “While most applications are related to optical memories where the optical information should be saved and released on demand,” he said, “there’s another fundamental aspect: Our studies combine optical and spin phenomena, and in this sense it’s very interesting to explore our approach for monitoring the time evolution of combined optical and spin excitations.”A unique feature of photon echo experiments is the dephasing which already occurs at the initial stage directly after excitation with the first pulse, where the sequence of two linearly polarized pulses create comprehensive spin distribution for excess electrons without net spin polarization. While each of the electrons has a certain well-defined spin, the ensemble spin polarization, or average spin, is zero – and the information about the optical pulses, such as polarization and interpulse delay, is encoded in the spins of excess electrons. “This differs from conventional techniques,” Akimov pointed out. “For example, in well-established pump-probe experiments the non-zero spin polarization in the system is first induced by a circularly polarized pump pulse, and then the evolution of the spin in time is probed.” The scientists therefore believe that their approach based on photon echoes in a magnetic field constitutes an interesting platform for fundamental spin studies.Along these exploratory lines, Phys.org asked Akimov if, given that storage times of seconds or longer might be possible by further exploiting the hyperfine interaction between electrons and nuclei in quantum dots, quantum wells and self-assembling quantum dots might at some point be combined in a single quantum system that emulates human short- and long-term memory. “I think we are still far from that,” he replied. “In order to achieve this goal it would be necessary to establish a net of such quantum dot ensembles, analogous to cells, which would communicate between each other.” He added that while he does not exclude such possibility, he emphasizes that such a quantum system would very complex and would contain and integrate far more than a simple set of quantum nanostructures. “Several challenging issues such as communication between different ensembles have to be addressed, and for that it is necessary to accomplish directed and selective coupling of light at the nanoscale in and out of the cells. Accordingly, realization of such a network would need integration of photonic crystals or waveguide layers which can be based on semiconductors. Nevertheless,” he concluded, “this is a special area of research which deserves a lot of attention.” 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. Scheme of photon echo experiment and optical properties of investigated structure. (A) The CdTe/(Cd,Mg)Te quantum well (QW) is optically excited with a sequence of three laser pulses with variable delays t12and t23 relative to each other. The resulting four-wave mixing transients |EFWM(t)| are detected in 2k2-k1 direction using heterodyne detection. All measurements are performed at temperature of 2 K. (B) Top: schematic presentation of exciton (X) and trion (T-) complexes in QW. The QW potential of conduction (CB) and valence (VB) bands leads to spatial trapping of electrons and holes. Bottom: Photoluminescence (PL) spectrum (solid line) measured for above-barrier excitation with photon energy 2.33 eV, demonstrating X and T- emission. The laser spectrum (dashed line) used in photon echo experiment is tuned to the low energy flank of T- emission line. (C) Four-wave mixing transients for t12 = 23 ps and t23 = 39 ps. Spontaneous (PE) and stimulated (SPE) photon echo signals appear at tref =2t12 and tref =2t12 +t23, respectively. (D) Decay of PE and SPE peak amplitudes. From exponential fits (dashed lines) we evaluate T2=72 ps and T1 = 45 ps. Credit: Ilya A. Akimov. Journal information: Nature Photonics Explore further Schematic presentation of the main mechanisms responsible for magnetic-field-induced stimulated photon echoes (SPE). The whole process comprises three steps: 1. pulse 1 creates the optical excitation (initialization—conversion of the optical field into a material excitation); 2. pulse 2 performs a transformation of the optical excitation into the spin system (storage); 3. pulse 3 stimulates the photon echo (readout). Optical pulses are circularly polarized. (A) Transfer of optical coherence into electron spin coherence (Sx and Sy components). The efficiency is maximum for t12=p/wL. (B) Creation of spectral spin fringes for electrons and trions (Sz and Jz components). This mechanism is most efficient for t12=2p/wL. The spectral spin gratings for electrons and trions are shown in (C) at the moment of creation by the second pulse (t=t12=2p/wL) and in (D) after trion recombination and before arrival of pulse 3 (t>>t12+T1). Credit: Ilya A. Akimov.center_img More information: Access to long-term optical memories using photon echoes retrieved from semiconductor spins, Nature Photonics (Published online 28 September 2014), doi:10.1038/nphoton.2014.219Related:1Magnetic-Field Control of Photon Echo from the Electron-Trion System in a CdTe Quantum Well: Shuffling Coherence between Optically Accessible and Inaccessible States, Physical Review Letters 109, 157403 (2 October 2012), doi:10.1103/PhysRevLett.109.157403 In their study, the researchers found that picosecond optical pulses and an applied weak transverse magnetic field led to the transfer of a short-lived optical excitation into a long-lived electron spin state. In turn, this induced stimulated photon echoes with high bandwidth on submicrosecond timescales that exceeded optical excitation lifetime by a factor exceeding three orders of magnitude. Moreover, the scientists state that the ability to address all three spin components –parallel and perpendicular to applied magnetic field – as well as the energy level structure of localized trions being identical in quantum wells and self-assembled quantum dots make their approach “highly appealing” for future memory device applications and may lead to the fabrication of semiconductor nanostructure-based optical memories.Dr. Ilya Akimov discussed the paper that he, Doctoral Student Lukas Langer and their co-authors from Dortmund, St-Petersburg and Warsaw published in Nature Photonics, starting with the main challenges in devising a new experimental approach to stimulated photon echoes by transferring the information contained in the optical field into a spin system, where it is decoupled from the optical vacuum field. “A photon echo can be considered as a flash of light initiated in a medium after a sequence of two or more optical pulses,” Akimov told Phys.org. “Properties of the photon echo pulse – that is, intensity, optical coherence and phase – are identical to the properties of the initial pulse; therefore this phenomenon can be used to store information in all-optical systems.” Photon echoes because they occur in structures which rapidly dephase optical excitation in response to the first pulse, but with the second pulse reverse the dephasing process. Akimov pointed out that the timescale at which photon echoes can be observed is determined by the period during which optical excitation coherence is preserved. “This is why photon echoes are coherent,” he explained. “If scattering processes are suppressed, optical excitation coherence is limited by its lifetime as governed by intrinsic properties of the materials. Nevertheless there is a general rule that the more efficient light-matter interaction, the faster decay into the ground state will be observed – for example, faster spontaneous emission due to the optical vacuum field. Here we have a dilemma,” he noted. “On the one hand, we’d like to excite the medium quickly with the shortest possible pulse, which requires strong light-matter interaction. However, this limits the timescale at which the photon echoes can be observed.” The opposite is also true: To observe long-lived photon echoes, materials with weak light-matter coupling are needed – and although semiconductor systems belong to materials with strong light-matter interaction, it’s possible to extend photon echo decay if the optical excitation is transferred into the spin excitation and then recovered back to the optical excitation – that is precisely what Akimov and co-authors have accomplished. Quantum holograms as atomic scale memory keepsake “In order to achieve this goal,” he said, “we’ve used semiconductor quantum wells with excess electrons.” (A quantum well is a thin layer which can confine quasiparticles – emergent phenomena that occur when a microscopically complicated system, such as a solid, behaves as if it contains weakly interacting particles in free space – in the dimension perpendicular to the layer surface.) What’s key is that the spin excitation coherence time of such electrons decays three orders of magnitude more slowly than the lifetime of optical excitations. “In our protocol the first pulse leads to optical excitation in semiconductor quantum well; next, after dephasing of the optical excitation the second pulse transfers optical excitation into the electron spin excitation; and finally – even after a long delay, which can be 1,000 times longer than the delay between the first and second pulses – we apply the third pulse.” This third pulse transforms spin excitation back to optical excitation and initiates rephasing, so that resulting photon echoes are retrieved from the spin ensemble – and therefore the third pulse can be associated with the readout of optical information previously saved by the optical-to-spin transformation induced by the second pulse.”The unique feature of photon echoes is that they contain the information about the first optical pulse,” Akimov pointed out. “Therefore, photon echoes can be used for information technology optical memory applications. Moreover, it’s possible to perform not only classical light storage but to use photon echoes for realization of quantum optical memories.” This is essential, he stresses, for the development of quantum information and communication systems which use the laws of quantum mechanics to significantly enhance the speed and capacity of future computers. Citation: There and back again: Extending optical storage lifetime by retrieving photon echoes from semiconductor spin excitations (2014, October 31) retrieved 18 August 2019 from https://phys.org/news/2014-10-optical-storage-lifetime-photon-echoes.html (Phys.org) —For all of their differences, classical and quantum communication have at least one thing in common: the importance of being able to store optical information. That being said, optical storage is a complex process that depends largely on the material being used to convert, store and retrieve this information in a controllable, consistent manner – a process especially prone to short optimal memory times when implemented in certain semiconductor quantum structures. Recently, however, scientists at Technische Universität Dortmund, Germany in collaboration with Saint Petersburg State University, Russia and Institute of Physics in Warsaw, Poland demonstrated magnetic-field-induced long-lived stimulated photon echoes1 – coherent optical phenomena in which resonant excitation of a medium by short optical pulses results in a delayed coherent optical flash response – in the electron–trion system, allowed the bidirectional coherent transfer of quantum information in a semiconductor between optical and spin excitations. (Trions are excitations comprising three charged quasiparticles – emergent phenomena that occur when a microscopically complex system, such as a solid, behaves as if it contained different weakly interacting particles in free space.)last_img read more

Govt mulls use of biofertilisers to boost plant productivity

first_imgKolkata: The state government is keen on increasing of productivity of various plants by administering bio-fertilisers and other manures, which will be fruitful for the plants.The Biotechnology department has already formed committees for the smooth implementation of various projects taken up by the department. Scientists and research fellows are conducting researches on bio-fertilisers about how they can be used to increase the productivity of various plants and vegetables. They will also save people from the toxic substances used in chemical fertilisers. Also Read – Speeding Jaguar crashes into Merc, 2 B’deshi bystanders killedIt has been learnt that researches are being conducted to examine how a particular plant can give fruits three times a year. Likewise, productivity of many other fruit trees and vegetables plants would be increased through various means, which will be more conducive for these plants to grow.According to sources, the state government has a plan to open a unit at all the districts, to provide technical assistance to the farmers on increasing the productivity of what they produce. Also Read – Naihati: 10 councillors return to TMC from BJPThe department is committed to ensure that the people can get vegetables, fruits and others foodgrains free from toxic substances at the markets.The department is also contemplating how the productivity of foodgrains and vegetables could be increased in comparatively unfertile areas of Bankura, Birbhum and Purulia. It may be mentioned that Chief Minister Mamata Banerjee had laid a lot of stress to improve the standard of life for the farmers in rural areas. She had announced lots of new projects in this regard. The scientists will also conduct “tissue culture” as a part of their research work in the district level to increase the productivity of plants. It has been seen that the vegetables and fruits that are supplied into various markets in the city, are often found to be unhealthy.It also affects human health as various chemical fertilisers rich in toxic substances are often administered to the plants to augment the productivity.The department will also carry out research on increasing the productivity of cattle. The state government will provide assistance to those who rear cattle.last_img read more

Power dept finalises DPL restructure plan

first_imgKolkata: The state Power department has finalised the restructure plan for Durgapur Projects Limited (DPL), a loss-making power utility, and has already forwarded the merger plan to the Electricity Regulatory Commission (ERC) for its approval.”We have finalised the restructure plan for DPL. The detailed plan has been sent to the ERC for its nod,” state Power minister Sobhandeb Chattopadhyay said. The minister informed that DPL will be divided into three parts. The transmission will be taken up by the West Bengal State Electricity Transmission Company Limited (WBSETCL) and the distribution will be looked after by the West Bengal State Electricity Distribution Company Limited (WBSEDCL) while the West Bengal Power Development Corporation Limited (WBPDCL) will take care of the generation part. Also Read – 3 injured, flight, train services hit as rains lash BengalThe Power department will offer Voluntary Retirement Scheme (VRS) to the employees. Those who will not opt for VRS will be posted at other similar units under the state government. “We will ensure that nobody who is willing to continue work lose his job. We will try to place all of them in Durgapur area itself as the employees have been working in the district for many years and it will be difficult for them to relocate to other places,” a senior official of the department said. Also Read – Speeding Jaguar crashes into Mercedes car in Kolkata, 2 pedestrians killedChief Minister Mamata Banerjee had made it clear in Durgapur in last year November that DPL cannot be saved without reconstruction. She added that the land belonging to the power utility would be sold and merged with other agencies. Banerjee handed over responsibility to state Labour and Law minister Moloy Ghatak, chairman of Asansol Durgapur Development Authority (ADDA) Tapas Banerjee, local MLA Biswanath Parial and Durgapur Mayor Dilip Agasthy to speed up the process of restructuring of DPL in association with the state Power department. The state Cabinet had sanctioned the merger of DPL in November 2017 after it was found that the power utility was having a negative net worth with its liabilities exceeding its assets plus shareholders equity amounting to almost Rs 1,000 crore. The losses have been to the tune of around Rs 200 crore every fiscal for a decade. It may be mentioned that with a total capacity of 660 MW, the state-owned DPL has been one of the most important industrial units in the Durgapur-Asansol belt. DPL has nearly 3,000 odd employees in its payrolls.last_img read more

Rep Leutheuser votes for balanced budget with more education road funding

first_img##### School safety. The plan dedicates roughly $60 million to upgrading school security in buildings across Michigan. The OK2SAY confidential tip reporting program will be expanded. Smart financial planning. The new budget pays down debt and puts more money into the state’s main savings account, key steps that will continue to reduce the burden on Michigan’s hard-working taxpayers in the future. Categories: Leutheuser News,News House Bill 5579 and Senate Bill 848 advance to the governor for his consideration. Legislator applauds emphasis on early learning, skilled trades 12Jun Rep Leutheuser votes for balanced budget with more education, road funding State Rep. Eric Leutheuser today voted to approve a state budget that prioritizes K-12 education and roads.Leutheuser, of Hillsdale, said the budget is fiscally responsible and reduces government spending while paying down debt. He said the plan addresses key priorities for hard-working taxpayers and families.“Teachers need to be free to do their good work. Our education budget places a priority on early literacy education to ensure children are reading at grade level by the end of third grade through additional instructional time and early literacy coaches.” Leutheuser said. “It is vital to the success of students to identify a literacy issue and provide the tools needed to give children a path to success.”Leutheuser also applauded increased emphasis on skilled trades instruction so students who choose not to go to college have the ability to fill in-demand, good-paying careers that are available throughout the state. This is something Branch and Hillsdale counties have begun already.Leutheuser said the budget continues to invest money into our roads and bridges to give families smoother, safer travel.“A decade ago, no money was budgeted by a previous administration for road upkeep. We’re playing catch-up,” Leutheuser said. “I drive the same roads we all do and I understand the frustration we share. We are on the right path for funding repairs to our transportation system.”Other key elements of the budget are:Savings for taxpayers. While investing more in top priorities, overall the state is spending less in the next budget year than during the current year. A prison will be closed and budgets for several state departments will decline as state government becomes more efficient and eliminates waste. Health care. Community mental health funding will increase by more than $65 million statewide so residents can live happier, more independent lives. Also supporting the House CARES initiative, about $15 million will be invested in a range of programs including increased access to health care, services to military veterans, problem-solving courts and crime victims’ rights programs. More resources also will be dedicated to battling the opioid abuse crisis.last_img read more

Cyfrowy Polsat has launched three Viasat channels

first_imgCyfrowy Polsat has launched three Viasat channels under a joint Polsat-Viasat banner as part of deal agreed last year between the two firms.The Modern Times Group-owned Viasat pay channels Viasat Explorer, Viasat History and Viasat Nature have now become Polsat Viasat Explorer, Polsat Viasat History and Polsat Viasat Nature on Polsat’s DTH satellite platform.Last year the two firms formed a strategic alliance to launch the co-branded channels in the Polish market early in 2013.The channels first went live under their Viasat names as part of Polsat’s Family HD package of channels in November. From January Polsat’s sales house Polsat Media started selling ads on the channels ahead of the planned rebrand.last_img

HIGHEST EVER HOUSEHOLD WASTE RECYCLING RATE LAST Y

first_imgHIGHEST EVER HOUSEHOLD WASTE RECYCLING RATE LAST YEAR – DUFFY was last modified: February 14th, 2018 by John2John2 Tags: SINN Féin spokesperson on Energy, Environment and Climate Change Councillor Sandra Duffy has welcomed the news that the North of Ireland recorded its highest ever household waste recycling rate last year.Councillor Duffy was commenting on figures released by the Department of Agriculture, Environment and Rural Affairs which showed that recycling rates from July to September 2017 increased from 48.4% in the same period in 2016, to 51.5% in 2017.“Increases in household recycling rates are welcome and will result in much needed environmental improvements.“We should continue to focus on building a culture of recycling which includes learning from best practice, developing the right infrastructure, incentives and public awareness campaigns. “I would continue to encourage everyone in the Derry and Strabane Council area to reuse, reduce and recycle and hopefully next year we will be setting a new waste recycling record,” she added. ShareTweet COUNCILLOR SANDRA DUFFYDerry and Strabane CouncilHIGHEST EVER HOUSEHOLD WASTE RECYCLING RATE LAST YEAR – DUFFYSinn Feinlast_img read more