(Visited 38 times, 1 visits today)FacebookTwitterPinterestSave分享0 A father-daughter team takes on the “selfish gene” concept and considers the ribosome as the “missing link” for lucky LUCA.“What does DNA want?” Meredith Root-Bernstein asks in The Conversation. “It wants to replicate” is the usual answer, pointed out by her father, Robert Root-Bernstein. But they notice that DNA does not naturally replicate itself. It coils up into a ball and resists change. Case in point:The resting position of DNA is very tightly curled up with its genes inaccessible. Resting DNA is so stable that it can protect its genes for 10,000 years or more, allowing scientists to recover DNA from frozen mammoths. This is not a molecule yearning to disperse its genes, but one that wants to conserve them by remaining curled up in a knot.We reasoned that the cellular structure that wants to copy genes and turn them into the proteins that make up functioning cells is ribosomes. The resting state of a ribosome is: “I’m ready to translate DNA into proteins.” Ribosomes “want” to convert genes into working molecules.So the question should be, “What does a ribosome want?” Ribosomes have machinery to build things. They want to make copies of themselves. So, the father-daughter team reasons, the “selfish gene” concept is wrong. The missing link to the Last Universal Common Ancestor (LUCA) must be the ribosome.But how could a functional ribosome appear out of primordial soup by chance? Since they’re anthropomorphizing anyway, here’s their solution:In a recent paper in the Journal of Theoretical Biology, we have shown that rRNA does contain vestiges of the mRNAs, tRNAs and “genes” that encode its own protein structure and function. Ribosomes are not simply the passive translators of genes as described in textbooks. We believe they are the missing link between simple pre-biotic molecules and the single-celled LUCA, the Last Universal Common Ancestor, considered to be the first living thing on Earth.DNA evolved to conserve and protect the information originally encoded in rRNA. Cells and organisms have evolved to optimise the replication of ribosomes, and ribosomes are almost the same across all species. Maybe the selfish ribosome puts a new spin on feeling kinship with other creatures. We are all just different kinds of homes to ribosomes.Given the complexity of a ribosome, it would appear a tall order to expect one to emerge out of a pool of “simple pre-biotic molecules”. Maybe it’s a spiritual essence about these molecules that gives them a sense of kinship.If you have heard a stupider theory about life than this, give us a call. Can you imagine the ridicule if a non-Darwinian wrote anything this lame as a “scientific” theory of the origin of life? Robert is a professor of physiology at Michigan State. It sounds like he was drunk on Darwine when he wrote this. What’s even more remarkable is that a journal would publish it. It goes to show that when people cease believing in God, they don’t believe in nothing; they believe in anything.At least their theory shows that the “selfish gene” concept is unworkable, too. If you retain any hopes that chance will build a ribosome, clear your head with our online book.
A Florida couple originally planned an extensive remodel, but ended up committing to green deconstruction, design, and rebuildingNo matter how much the downturn rattles the housing market, location is still king, and it is such a potent factor for some homebuyers that it can make up for a host of unforeseen issues in a listing.That turned out to be the case for Claire Sever and Jeff Bunkin, who bought a house in a Gainesville, Florida, neighborhood that is close to the center of town. They originally planned an extensive remodel, but financial realities and an interest in green took them down a different path.It became apparent, for starters, that the cost of remodeling the 1,600-sq.-ft. home was comparable to the cost of building a new house. Claire and Jeff chose to do the latter. They took a decisive turn by careful deconstruction and salvaging, followed by sustainable design and building.A patient approachThe couple’s green-build odyssey, described in a recent article published by The Gainesville Sun, included the use of Bearded Brothers Solutions, a specialist in deconstruction and resale of used building materials, and a design plan that included not only energy-efficient strategies but a ranch-style exterior that meshes well with those of other homes in the neighborhood.Working with a local builder, Ivan Solbach, Clair and Jeff thought through how each room in the two-story 2,400-sq.-ft. house would be used, even after their two daughters depart for college years from now.Steel-and-Styrofoam SIPs support the building’s reflective metal roof, and the shell’s 2×4 framing is insulated with spray foam. Solbach says many clients still opt to spend money on fancy finishes, such as granite countertops, over energy-efficient extras, but the opposite was true for Clair and Jeff, who equipped their home with a solar hot-water system, a 4.69-kW photovoltaic sytstem, low-e windows, and a 1,500-gal. underground cistern that collects water for irrigating the property’s drought-tolerant indigenous plants.There’s evidence all this commitment to green will yield significant long-term benefits: As the Sun notes, the house earned a HERS index rating of 37 and has already been certified as “Florida Friendly” by FloridaYards.org, a joint program of the Florida Department of Environmental Protection, the University of Florida’s Institute of Food and Agricultural Sciences Extension Program, and other state agencies.
Zane Bridgers is building a single-story house in northern New Mexico and has nearly completed the framed exterior walls. As his mind turns to air sealing, he’s considering whether to install an interior vapor barrier — and whether his uncle, a builder of 40 years, is giving him good advice on how to proceed. Walls on the slab-on-grade structure will include R-19 fiberglass cavity insulation, 5/8-inch OSB sheathing, a 2-inch layer of polyiso rigid insulation, a drainage layer and, finally, three-coat stucco. In the roof, Bridgers plans 6-mil poly under the drywall, followed by 2 inches of polyiso, R-38 fiberglass batts, a 2-inch ventilation channel, OSB sheathing and metal roofing. “This is a predominately cold and dry heating climate with big temperature swings,” Bridgers writes in a Q&A post of the Climate Zone 5 locale. “I was talking with my uncle who has been a builder here for 40 years. He was explaining the importance of dry heat for optimal performance of fiberglass insulation, hence his recommendation to put the 6 mil plastic on the ceiling … I was planning to tape the foil faced polyiso for this effect, but he thinks it’s a waste of time and effort vs. the 6 mil poly.”RELATED ARTICLESWorries About Trapping MoistureSite-Built Ventilation Baffles for RoofsCalculating the Minimum Thickness of Rigid Foam SheathingOne Air Barrier or Two?Vapor Retarders and Vapor Barriers Bridgers is equally concerned about another bit of advice he’s been given: Add a layer of poly to the walls. “This caused a bit more concern as it seems it could potentially trap moisture in the wall cavity, especially since I had planned foil-faced polyiso under the stucco, also taped,” Bridgers adds. “He suggested leaving somewhere for the moisture to go.” Bridgers has two other questions. First, is it a waste of time to seal the OSB and framing when the exterior foam and drywall seem like much easier ways of controlling air leaks? And second, with a continuous layer of rigid foam over the wall sheathing, where is the point in the assembly where condensation is likely to occur? Those concerns will get us started on this Q&A Spotlight. Water doesn’t need to escape GBA editor Martin Holladay, referring Bridgers to an article he had written on the topic previously, notes that interior moisture doesn’t really need to go anywhere. “Water doesn’t need to escape from your house,” Holladay writes. “Although it’s true that indoor air is warm and humid during the winter, while outdoor air is cold and dry, that doesn’t mean that indoor moisture needs to ‘escape’ from your house. It’s perfectly OK if the indoor moisture stays where it is without ‘escaping.’ ” Holladay explains that walls with exterior rigid foam should never have interior polyethylene, since foam-sheathed walls need to be able to dry to the interior. Either polyiso or expanded polystyrene (EPS) insulation would make a good choice, and taping the seams would be time well spent. “Air sealing efforts are almost never a waste of time,” he says. “Whether or not you need redundancy (basically, multiple air barriers) depends on your airtightness target and your budget.” What about Bridgers’ concerns about condensation inside the walls? “The idea is to specify enough rigid foam on the exterior of your wall sheathing so that condensation does not occur,” Holladay says. “In your climate zone, your rigid foam needs a minimum R-value of R-7.5 if your walls are framed with 2x6s. “Skip the interior polyethylene,” he adds, “pay attention to airtightness, and everything will be fine.” What about venting the roof? If the walls are better off without the poly, should it still be used in the ceiling? Bridgers asks. There’s no code requirement for including a vapor barrier on the interior side of a vented roof assembly, Holladay replies. The most important thing is airtightness, not preventing vapor diffusion. Drywall can be an air barrier, providing Bridgers pays close attention to sealing any penetrations, particularly the electrical boxes. Bridgers sees a problem with adding foam or plastic ventilation baffles above the fiberglass in the roof because either would prevent moisture from being wicked out of the insulation. “The purpose of the vent channel is to help keep the roof sheathing dry,” Holladay says. “You are not trying to wick moisture out of the fiberglass … You aren’t trying to help indoor moisture escape. It’s OK if indoor moisture stays where it is, all winter long.” One air barrier is enough Peter Engle writes that Bridgers has three potential air barriers in the ceiling: the foil facing on the foam insulation, the poly, and the drywall. “You only need one, well detailed and airtight,” Engle says. “If you can make the drywall airtight, you can skip the poly and use any polyiso foam you want, or EPS foam. If you are worried about the drywall being airtight, you can tape the seams in the foil polyiso.” Jon R, however, suggests there’s nothing wrong with multiple air barriers. “More air barriers will generally outperform one,” he says. “If you can only have one, the best (for your climate) is the interior side.” Addressing the risk of condensation Jon R adds that the choice of exterior foam may make a difference to how well the wall performs: “With external foam, a wall that can dry a little to the exterior (say EPS) will outperform a similar wall that can’t (say same R-value of foil-faced foam).” He takes issue with the idea that a wall must be designed so that there is a zero chance of condensation taking place. “The idea is to reduce the amount of condensation to the point where it sometimes occurs but isn’t enough to cause a problem,” he writes. “Going beyond that, all the way to ‘no condensation’ is unnecessary expense. Some in-wall condensation *will occur* at the minimum recommended foam R values.” Holladay replies: “When sheathing is cold in the winter, and in contact with warm humid air, what happens isn’t really condensation. It’s sorption. The moisture content of the cold OSB or plywood sheathing increases when the warm humid air is in contact with it.” That said, the building science in this case is clear. When the exterior foam is thick enough, the sheathing stays dry. If the foam is too thin, the siding may get damp, which is risky. With that in mind, Bridgers asks, would a 2-inch layer of polyiso with an R-value of 13 be a better bet than a 2-inch layer of EPS, with an R-value of 8? “That’s exactly the right type of question,” Jon R replies. “WUFI might provide a useful answer. Forced to weigh various factors and guess in your case (never a good way to do design), I’d say the R-13. Better than either if it were unfaced/higher perms.” Agreed, says Holladay: R-13 is preferable to R-8. Our expert’s opinion GBA technical director Peter Yost made the following points: Cavity or interstitial condensation: There are two primary drivers of this phenomenon: the difference in temperature between the interior and exterior, and the interior relative humidity. Yes, it’s plenty dry in New Mexico during the winter, but occupants can generate quite a bit of moisture (for more, see this). So, make sure you manage interior sources of moisture and have humidity-sensing devices so that occupants know what the interior relative humidity is. Location and nature of air control layer/barrier: If I only get to choose one location for an air barrier, I choose the exterior, for two reasons. One, it’s much easier to get continuity on the exterior (no intersecting interior partitions or floor assemblies to worry about). Two, exterior air barriers deal better with wind-washing at the corners of buildings. Continuity is key. It’s easy to designate elements of the air control layer, but more difficult to get them all connected. Pick one plane for the air barrier, and then make it continuous. If you can get more than one air barrier, great. But one continuous barrier is way more beneficial than two or more discontinuous ones. Building assembly drying potential: It’s ideal to select every individual layer of an assembly (based on vapor permeance) so that there is drying in both directions, but our assemblies are complex enough these days that settling for drying potential in one direction is reasonable. Avoid selecting Class I — and if you can, Class II — vapor retarding materials on one side of your assembly or the other to get that single-direction drying potential. Bottom line: There’s absolutely no need for polyethylene. Don’t put in a Class I vapor retarder/barrier unless you have to.
Every 18 seconds someone is diagnosed with HIV Panelo suggests discounted SEA Games tickets for students PLAY LIST 01:35Panelo suggests discounted SEA Games tickets for students02:49Robredo: True leaders perform well despite having ‘uninspiring’ boss02:42PH underwater hockey team aims to make waves in SEA Games01:44Philippines marks anniversary of massacre with calls for justice01:19Fire erupts in Barangay Tatalon in Quezon City01:07Trump talks impeachment while meeting NCAA athletes Lacson: SEA Games fund put in foundation like ‘Napoles case’ Pagasa: Storm intensifies as it nears PAR MOST READ Don’t miss out on the latest news and information. BREAKING: Cop killed, 11 hurt in Misamis Oriental grenade blast Palace: Duterte to hear out security execs on alleged China control of NGCP Sports Related Videospowered by AdSparcRead Next BREAKING: Cop killed, 11 hurt in Misamis Oriental grenade blast Geje Eustaquio declared the winner. Photo from ONE CHAMPIONSHIPGeje Eustaquio believes that his split decision victory against Thai foe Anatpong Bunrad in ONE: Dynasty of Heroes in Singapore on Friday was more decisive than how the judges saw it.“I was surprised with the three judges’ decision. I was expecting a unanimous decision win against my opponent,” he said.ADVERTISEMENT BSP survey: PH banks see bright horizon amid dark global recession clouds D-League: Batangas downs debuting Marinerong Pilipino Cayetano dares Lacson, Drilon to take lie-detector test: Wala akong kinita sa SEA Games LATEST STORIES Still, Eustaquio expressed his satisfaction with the turnout, which improved his record to 9-5.“I am good with it. I respect it,” he said. “I am so happy whether it’s split or unanimous. I am the winner. I respect the three judges’ decision. I know I did my best inside the cage.”And the Baguio native guns to further make his ascent in the ONE Championship flyweight ranks with this bounce back victory.“It’s a breath of fresh air. I am back on the winning side. Of course, this will not be the end. There will be new assignments in the future. Anyone who wants to face me next, I am ready to dance with you,” ended Eustaquio.ADVERTISEMENT Fending off a slow start, the 28-year-old striker recovered in rounds two and three, where he dictated the tempo of the match with his excellent footwork and superb counterpunching, landing leg kicks and right straights to frustrate Bunrad.“Rounds two and three, I knew it’s all mine because I was landing my strikes. I was consistent with that. My work rate was much better this time around as well,” he said.FEATURED STORIESSPORTSSEA Games: Biñan football stadium stands out in preparedness, completionSPORTSMalditas save PH from shutoutSPORTSPrivate companies step in to help SEA Games hostingAnd Eustaquio had no doubts on whose hands will be raised when the buzzer sounded. What caught him off guard, though, was the way how the judges scored the bout.“After the third round, I was already confident that I won the fight. From my view, I got two rounds to one,” he said. View comments