United have been revitalised on a run of nine wins and a draw in 10 games since Jose Mourinho was sacked and Ole Gunnar Solskjaer appointed as his replacement. They are likely to be a fearsome proposition in next Tuesday’s first leg.Meanwhile, Thomas Tuchel’s men are a massive 10 points clear at the top of Ligue 1 with two games in hand on the teams below them as they prepare to welcome mid-table Bordeaux to the Parc des Princes, and are also through to the quarter-finals of the French Cup.However, they needed extra time to beat third-tier side Villefranche-sur-Saone 3-0 in the Cup on Wednesday, three days after seeing their unbeaten league record this season ended in a 2-1 defeat at Lyon.They were knocked out of the League Cup by struggling Guingamp in the quarter-finals last month, and since then Paris have lost Neymar to a metatarsal injury.The Brazilian is not expected back until early April, but the worries do not stop there.– Sweating over Verratti –Looking increasingly irritated of late, Tuchel admitted after the Cup tie in midweek that some of his squad had played too much football in recent weeks.Marco Verratti hasn’t played for three weeks, but PSG will need him at Old Trafford © AFP/File / KARIM JAAFARSaturday’s match will be their ninth of 2019, and Tuchel has too small a squad to rest certain key players.“We lack dependable, top quality players,” said the German, offering an explanation for his side’s struggles against lesser opposition.“We cannot make the mistake of expecting too much from players like (Eric Maxim) Choupo-Moting, who have not played much.”PSG may be one of the richest clubs in the world, spending the two biggest transfer fees in football history to attract Neymar and Kylian Mbappe in 2017, but the Qatar-owned side have not invested enough in other parts of their squad.The midfield is the greatest concern, even if Argentine international Leandro Paredes made his full debut against Villefranche after signing from Zenit Saint Petersburg for 47 million euros ($54 million).Adrien Rabiot is still frozen out over his refusal to sign a new contract, while Marco Verratti has not featured in three weeks due to an ankle injury.He returned to training earlier this week, but it remains to be seen if he will be fit to face Bordeaux. There are few other options.“Verratti was unable to finish training (on Tuesday). He has had problems, and we need to wait to see if he can play against Bordeaux,” said Tuchel on Wednesday night.“He has a different problem now, but I don’t know too much.”Beating Bordeaux is more about boosting morale than it is about staying ahead in the title race, with Lille focused on holding on to second place as they go to bottom club Guingamp.Impressive in beating PSG, third-placed Lyon are building towards their Champions League tie with Barcelona on February 19. They go to Nice on Sunday.At the other end of the table, struggling Monaco are chasing a second straight league win as they visit Montpellier.FixturesFridayDijon v Marseille (10:45pm)SaturdayParis Saint-Germain v Bordeaux (7pm), Amiens v Caen, Strasbourg v Angers (both 10pm)SundayMontpellier v Monaco, Nantes v Nimes, Toulouse v Reims (all 5pm), Guingamp v Lille, Rennes v Saint-Etienne (both 7pm), Nice v Lyon (11pm)0Shares0000(Visited 1 times, 1 visits today) 0Shares0000Neymar’s injury means there is more of an onus on Kylian Mbappe, but are Paris Saint-Germain’s real problems elsewhere? © AFP/File / JEFF PACHOUDPARIS, France, Feb 8 – Paris Saint-Germain’s meeting with Bordeaux on Saturday is their last chance to do some fine-tuning before next week’s showdown with Manchester United, but the Ligue 1 leaders have some major issues to contend with before heading to Old Trafford.PSG were the strong favourites when the draw for the Champions League last 16 was made, yet much has changed in the eight weeks since.
The researchers, Parthiban Santhanam and coauthors from MIT, have published their study in a recent issue of Physical Review Letters.As the researchers explain in their study, the key to achieving a power conversion efficiency above 100%, i.e., “unity efficiency,” is to greatly decrease the applied voltage. According to their calculations, as the voltage is halved, the input power is decreased by a factor of 4, while the emitted light power scales linearly with voltage so that it’s also only halved. In other words, an LED’s efficiency increases as its output power decreases. (The inverse of this relationship – that LED efficiency decreases as its output power increases – is one of the biggest hurdles in designing bright, efficient LED lights.)In their experiments, the researchers reduced the LED’s input power to just 30 picowatts and measured an output of 69 picowatts of light – an efficiency of 230%. The physical mechanisms worked the same as with any LED: when excited by the applied voltage, electrons and holes have a certain probability of generating photons. The researchers didn’t try to increase this probability, as some previous research has focused on, but instead took advantage of small amounts of excess heat to emit more power than consumed. This heat arises from vibrations in the device’s atomic lattice, which occur due to entropy.This light-emitting process cools the LED slightly, making it operate similar to a thermoelectric cooler. Although the cooling is insufficient to provide practical cooling at room temperature, it could potentially be used for designing lights that don’t generate heat. When used as a heat pump, the device might be useful for solid-state cooling applications or even power generation.Theoretically, this low-voltage strategy allows for an arbitrarily efficient generation of photons at low voltages. For this reason, the researchers hope that the technique could offer a new way to test the limits of energy-efficiency electromagnetic communication. Explore further Citation: LED’s efficiency exceeds 100% (2012, March 5) retrieved 18 August 2019 from https://phys.org/news/2012-03-efficiency.html 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.