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Inner Ear Hair Cells Overcome Friction

first_img The human ear has an extraordinarily large sensitivity range of a trillion to one, allowing us to hear a rocket launch or the footfalls of a cat on a carpet.  According to Werner Gitt, the ear is our highest-precision sense organ, capable of responding over twelve orders of magnitude without switching (The Wonder of Man, p.21).  Some of this sensitivity is amplified by the eardrum and middle ear ossicles, but the paper reported above shows even more fine-tuning inside the cochlea.  Gitt’s book is highly recommended for generating a profound feeling of awe over the design of our senses.  Proverbs said, “The seeing eye, and the hearing ear, the Lord has made them both” (Prov. 20:12).(Visited 48 times, 1 visits today)FacebookTwitterPinterestSave分享0 The cochlea, that spiral-shaped structure in the inner ear, is filled with fluid.  In this fluid, tiny hair cells called stereocilia are positioned in bundles along the length of the structure.  These bundles sense vibrations transmitted into the fluid from the bony levers of the inner ear.  The vibrations picked up by the hair cell bundles, each tuned to its own frequency, mechanically transduce the sound impulses by opening ion channels that set up electrical impulses in the auditory nerve, that travel to the brain.  But motion in fluid creates friction known as viscous drag.  How do the hair cell bundles overcome it?  Scientists have figured out that the hair cells in the bundles are not only finely tuned to reduce viscous drag, but actually to employ it for even higher sensitivity to sound. Publishing in Nature,1 scientists from Howard Hughes Medical Institute, with help from European academies, explained the problem of viscous drag, and two ways the ear deals with it: The detection of sound begins when energy derived from an acoustic stimulus deflects the hair bundles on top of hair cells.  As hair bundles move, the viscous friction between stereocilia and the surrounding liquid poses a fundamental physical challenge to the ear’s high sensitivity and sharp frequency selectivity. Part of the solution to this problem lies in the active process that uses energy for frequency-selective sound amplification.  Here we demonstrate that a complementary part of the solution involves the fluid-structure interaction between the liquid within the hair bundle and the stereocilia. What they found is that the positioning of the individual stereocilia causes them to move in concert, so that viscous drag within the bundle is dramatically reduced: “We find that the close apposition of stereocilia effectively immobilizes the liquid between them, which reduces the drag and suppresses the relative squeezing but not the sliding mode of stereociliary motion.”  They can thus slide as the bundle bends without stirring up the liquid.  Further, “The obliquely oriented tip links couple the mechanotransduction channels to this least dissipative coherent mode, whereas the elastic horizontal top connectors that stabilize the structure further reduce the drag.”  The relative motion is reduced to just a fraction of a billionth of a meter (nanometer). Their opening paragraph provides a picturesque view of the workings of this remarkable organ: A hair bundle is a microscopic array of quasi-rigid, cylindrical stereocilia separated by small gaps filled with viscous endolymph. Like an array of organ pipes, the stereocilia vary monotonically in length across the hair bundle…. The tip of each short stereocilium is attached to the side of the longest adjacent stereocilium by a tip link, the tension in which controls the opening and closing of transduction channels. Adjacent stereocilia are also interconnected along all three hexagonal axes by horizontal top connectors. At the tall edge of the bundle in many species stands a single kinocilium, the process to which mechanical stimuli are applied and that is ligated to the adjacent stereocilia by kinociliary links. Why are the stereocilia arranged in bundles?  “The small difference between the drag coefficients for a single stereocilium and for an entire hair bundle reveals the striking advantage that grouping stereocilia in a tightly packed array offers to the auditory system.”  Using models from a bullfrog inner ear magnified 12,000 times and various mathematical techniques, they were able to measure the viscous drag of the coherently-arranged stereocilia.  Their conclusion explains how the findings contribute to understanding the remarkable sensitivity of the ear: In conclusion, because all stereocilia and the liquid between them move in unison over the whole auditory spectrum, with the relative motions apparent only on a sub-nanometre scale, most stereocilia inside the hair bundle are shielded from the external liquid and experience little viscous drag. Although viscous forces might be thought to impair sensitivity and frequency selectivity, the hair bundle’s structure actually minimizes energy dissipation, making it easier for the active process to keep the ear tuned. The tight clustering of stereocilia even transforms liquid viscosity into an asset by using it as a simple means of activating numerous mechanosensitive ion channels in concert. The authors made no attempt to explain how this arrangement might have evolved.  1. Koslov, Baumgart et al., “Forces between clustered stereocilia minimize friction in the ear on a subnanometre scale,” Nature  474   (16 June 2011), pp. 376–379, doi:10.1038/nature10073.last_img read more

Zoho Makes Another Move to be the IT of the Small Business Market

first_imgIT + Project Management: A Love Affair It’s clear that Zoho is gunning for the enterprise market with a focus on the small business sector. The company is increasingly perceived as a competitive threat to larger, more established companies. This is illustrated by a Microsft executive’s remark earlier this month that Zoho is a “fake” Microsoft office.Zoho responded with FakeOffice.org, featuring a video they made in September, renaming it “Fake Office – the Movie.” Zoho is a challenger to Salesforce.com in the small business market, which has moved up market in the past few years. That approach has worked for Salesforce but in these markets the company faces deep pressures from larger competitors such as Oracle.Zoho faces its own competition but it has a unique approach. Its products are varied, giving customers the feeling that they are using a service that is customized for their particular needs.Plus, we like their videos. 🙂 They explain their products. How about that? Tags:#enterprise#news#Products#saas Cognitive Automation is the Immediate Future of… alex williamscenter_img Related Posts 3 Areas of Your Business that Need Tech Now Zoho is making another move to serve as the IT department for the small business market. Its latest offering is a service for staffing agencies and human resources to automate the process for hiring people. The new service, available now, is an applicant tracking system that helps staffing agencies and recruiting departments track job openings, resumes and candidates. The enterprise is stil heavily dependent on email and manual processes for any number of practices with human resources being no exception to the rule. Zoho’s strategy is to create a level of automation that makes a human resources functions manageable, a model they have used for the services they offer for sales, marketing and other functions in the enterprise.Zoho Recruit has a number of features including web forms; the ability to aggregate resumes from social sites and ways to track the status of a client within the application.Activity streams are emerging as a standard for new social enterprise products. In Zoho Recruit, though, the activity streams look more like simple views into the status of a job opening, profiles of other people on the team and the interviews on schedule for the day. Here’s an overview of Zoho Recruit: Massive Non-Desk Workforce is an Opportunity fo…last_img read more

Visiting Passivhaus Job Sites in Washington State

first_img Sign up for a free trial and get instant access to this article as well as GBA’s complete library of premium articles and construction details. Start Free Trial Already a member? Log in On March 16, 2011, I flew to Seattle for a three-day visit to Washington state. Although the main purpose of my visit was to attend the spring conference of Passive House Northwest, I devoted a day and a half to visiting Passivhaus buildings and construction sites in Seattle and Olympia. With the help of my gracious hosts, Dan Whitmore and Albert Rooks, I was able to see four Passivhaus sites and a large workshop where Passivhaus wall panels were being assembled indoors.Because I packed in so many site visits and interviews in my short visit to the Northwest, it will take at least two blogs to report on my trip. Here’s the first installment.Dan Whitmore is a Seattle builder who kindly volunteered to pick me up at the airport and offer me accommodations for my first night out West. On the way back to his place, we swung by the Phinney Neighborhood Association in Seattle to visit the Mini-B Passive House, a tiny cabin that now sits in a parking lot until the modular building finds a permanent home. The architect of the Mini-B, Joe Giampietro, met us there and gave us a tour.The Mini-B — short for “mini bungalow” — was designed to meet the “detached accessory dwelling unit” requirements of Seattle’s building code. The city allows homeowners to install these small backyard buildings for use as guest rooms or mother-in-law apartments.Giampietro wanted his Mini-B prototype to meet the Passivhaus standard. As he dove into the design process, he learned first-hand that the Passivhaus standard is much easier to achieve with a large building than a small one. Fortunately, Seattle’s climate is relatively mild, and Giampietro was able to achieve his goal — even though the Mini-B measures only 300 square feet.Since high-performance triple-glazed windows gather more… center_img This article is only available to GBA Prime Memberslast_img read more

Star, Alaska in key duel

first_imgBSP survey: PH banks see bright horizon amid dark global recession clouds Pagasa: Storm intensifies as it nears PAR The only way for Star to make it outright is for the Hotshots to beat Alaska and hope that Ginebra or San Miguel—or both—drop one game in closing out the round.But that seems highly unlikely since San Miguel and Ginebra are playing great at the moment and the Beermen are closing out against the lightweight Elite and GlobalPort on Friday at Smart Araneta Coliseum.The Gin Kings, meanwhile, have back-to-the-wall Mahindra as their final foe also on Friday as they put a three-game winning streak on the line.The game is as important to Alaska as it is to Star as the Aces welcome Calvin Abueva back to active duty in a bid to snap a six-game losing streak.A win by Alaska would most likely put the Aces in the middle of the pack—and in a best-of-three series. A loss puts the Aces in danger of needing to win three straight knockout matches to make it to the Final Four.ADVERTISEMENT Every 18 seconds someone is diagnosed with HIV Sports Related Videospowered by AdSparcRead Next Palace: Duterte to hear out security execs on alleged China control of NGCP ‘Time to prove yourself’ LATEST STORIES Lacson: SEA Games fund put in foundation like ‘Napoles case’ 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 athletescenter_img Calvin Abueva goes up for a shot. Photo by Tristan Tamayo/INQUIRER.netWith its outright place in the top two PBA Commissioner’s Cup not resting entirely in its hands, Star tries to do what it can on the floor on Wednesday before hoping that the results in the final two elimination round playdates favor the Hotshots in their twice-to-beat drive.Star takes on Alaska at 7 p.m. at Cuneta Astrodome in Pasay, and the Hotshots need a win that would also put the Aces’ playoff chances in jeopardy.ADVERTISEMENT BREAKING: Cop killed, 11 hurt in Misamis Oriental grenade blast MOST READ View comments San Miguel Beer, meanwhile, also steps up its top two chase when it collides with Blackwater at 4:15 p.m.The Hotshots are currently tied for the lead with idle Barangay Ginebra at 8-2, but even a win against the Aces will not guarantee them an outright quarterfinal bonus.FEATURED STORIESSPORTSSEA Games: Biñan football stadium stands out in preparedness, completionSPORTSMalditas save PH from shutoutSPORTSPrivate companies step in to help SEA Games hostingStar could eventually be dragged into a playoff for the second privilege if the Gin Kings and the Beermen sweep their remaining assignments.That is because both San Miguel and Ginebra can end up with 9-2 records, and when the tiebreaker is applied, the Hotshots are in a deep predicament since their two losses came from the Beermen and the Gin Kings. BREAKING: Cop killed, 11 hurt in Misamis Oriental grenade blast Don’t miss out on the latest news and information. Cayetano dares Lacson, Drilon to take lie-detector test: Wala akong kinita sa SEA Gameslast_img read more

TNT’s Pogoy scoreless since career performance in Game 1

first_imgRoger Pogoy. PBA IMAGESMuch-maligned after his apparent low-blow against Arwind Santos in Game 2, Roger Pogoy shared that he has already extended his apologies to his fellow Tamaraw.“That’s over with. I don’t have any comment on that. I already apologized to kuya Arwind,” he said in Filipino.ADVERTISEMENT Pogoy shrugged off his bad shooting and insisted that his main job is to be one of the KaTropa’s defensive anchors.“My role here in this team is to do the defense and the little things. The points I get are just bonuses. I want to do my role here in the team so that we can win,” he said.Sports Related Videospowered by AdSparcRead Next View comments Cayetano to unmask people behind ‘smear campaign’ vs him, SEA Games Ethel Booba on hotel’s clarification that ‘kikiam’ is ‘chicken sausage’: ‘Kung di pa pansinin, baka isipin nila ok lang’ Robredo: True leaders perform well despite having ‘uninspiring’ boss PLAY LIST 02:49Robredo: 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 athletes02:49World-class track facilities installed at NCC for SEA Games LATEST STORIES 1 dead in Cavite blast, fire World’s 50 Best Restaurants launches new drinking and dining guide Heart Evangelista admits she’s pregnant… with chickencenter_img Don’t miss out on the latest news and information. MOST READ Jeff Horn has ’10-point plan’ to upset Pacquiao Lacson: SEA Games fund put in foundation like ‘Napoles case’ What ‘missteps’? “Maybe it’s just bad game. They were really closing out on me. Before, they are letting me shoot and they’re challenging everything. I’ll make up for it next game,” he said.TNT coach Nash Racela also isn’t losing sleep with Pogoy’s poor two-game stretch, noting that though, the FEU standout has been missing his shots, he’s still able to contribute in other ways.“It’s okay as long as he’s making the right decisions and taking the shots that he needs to take. If he’s open, it’s okay. If it doesn’t go in, there’s no problem,” Racela said.“I think it’s the same with (Marcio) Lassiter. He was struggling a little bit but he was taking the right shots. Today, he contributed, starting hitting his shots. So it is what it is.”For his part, Pogoy noted that more than his offense, it’s his defense which is counted more in the KaTropa camp as he expects a tougher battle against the likes of Lassiter, Alex Cabagnot, and Chris Ross come Game 4 on Wednesday.ADVERTISEMENT The TNT rookie has put the incident behind him but things haven’t been going well for him in the finals since.For the second straight game, Pogoy was held scoreless two games after having a career performance in Game 1.FEATURED STORIESSPORTSSEA Games: Biñan football stadium stands out in preparedness, completionSPORTSPrivate companies step in to help SEA Games hostingSPORTSMalditas save PH from shutoutAnd t’s no surprise that the KaTropa yielded Game 3 to the Beermen, 109-97, with Pogoy dealing with major offensive woes.Pogoy is currently 0-of-13 from the field after exploding for  27 points in the finals opener. WATCH: Firefighters rescue baby seal found in parking garagelast_img read more

LG V40 ThinQ set to launch in New York on October 3

first_imgThe word is out. Korean tech giant, LG, has started sending invites for the global debut of its upcoming flagship device- LG V40 ThinQ. The company will unveil the device at a special event in New York on October 3 and in Seoul on October 4.Along side revealing the launch date of its next V-series smartphone, the Korean electronics giant has also shared a 10-second-long video clip that shows images being captured from three different angles. This could indicate that the phone could sport a triple-camera setup at the back, a feature that rumours circulating about the phone have touted for long.Besides having a triple rear camera setup, the phone is also rumoured to sport a dual camera setup with an 8MP and a 5MP sensor in the front. The front camera is likely to support 3D face unlocking technology.As far as other specifications are concerned, the upcoming LG V40 ThinQ is likely to sport a 6.4-inch quad HD POLED notched display with IP68 water and dust resistant technology. It is expected to be powered by Qualcomm Snapdragon 845 system-on-chip and run on either on Android 8.0 Oreo or Android 9 Pie. In terms of memory, the device is likely to sport 6GB RAM with either 64GB or 128 GB storage space.The phone is also likely to come feature support for Quad DAC and Stereo Speaker Boombox audio technologies and come with a 3,300mAh battery.If the rumours are to be believed, the upcoming LG V40 ThinQ will measure 158.7×75.8×7.79 mm. It will have a fingerprint sensor which is placed vertically beneath the horizontally stacked cameras. The phone is expected to sport think bezels on the top and button and come with a dedicated button for Google Assistant, just like G7 Plus, which will be placed on the left side of the phone.advertisementALSO READ: LG V40 ThinQ inches closer to launch after FCC certificationMeanwhile, earlier this week, the phone was certified by the Korean National Radio Research agency and Global Certification Forum. And now the phone has been certified by the FCC in the US. As per the reports, LG could work with all the network operators in the US including, Verizon and Sprint, to bring its flagship device to the market.last_img read more