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You can now invite anyone to meet at your favorite Starbucks.
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36 year old man | San Mateo, CA, USA | Seeking women 25-45 within 30 miles
Always Look To The Bright Side of Life.
I am someone who enjoys to laugh above all. I'm the jackass who will somehow fall down and yet find it very amusing. I am also a geek. A sports geek and a tech geek mostly. I'm a huge SF Giants and 49er fan, as well as a Sharks fan. Yes, hockey. One of my favorite things to do is wander with my camera and take pictures. I'm a pretty straight forward guy, I am looking for someone who has a sense of humor, someone who has an opinion and will challenge me, someone who would like to hang out and watch a movie, or even go drink at a bar with me. And if you know the movie my headline is from, brownie points for you. I'd love to meet some new people, so drop me a line if your interested.
Coffee and conversation , Movies/Videos , Museums and art , Playing cards , Playing sports , Political interests , Travel/Sightseeing , Video games , Watching sports
Baseball, Basketball, Billiards / Pool, Football, Golf, Hockey, Other types of exercise, Tennis / Racquet sports, Weights / Machines
I exercise 3-4 times per week.
I have Cats
Some of my favorite spots, McGoverns, Molloys, Kels. I like checking out new places. More of a fan of the whole in the wall bar than a club. I enjoy being able to have a conversation with someone.
San Francisco State University, San Francisco, CA
Some of my favorite things include playing and watching sports. I love playing poker, especially when I win. I enjoy watching movies and television. Got to love Smallville, The Office, and TV on DVD is great, commercial free.
Sports, poker, movies, road trips. I like taking my camera out and looking for a new place to shoot.
I have a couple of magazine subscriptions, the newspaper. As far as books, currently reading a book about Edward R. Murrow. Previous reads include Outliers, the Dan Rather Bio, Quiet, The Big Short, the Steve Jobs biography, and some others.
Z{{Cta}} {{#if HasMoreInfo}} ?{{CtaSecondary}} {{/if}}
|What he is looking for
|5'7" (170cms)
|4'8" (142cms) to 7'0" (213cms)
|Body type:
|No preference
|No preference
|Light brown
|No preference
|No Way
|No preference
|Social Drinker
|No preference
|Technical / Science / Computers / Engineering
|No preference
I work at a Bay Area television station and love my job. I do have some interesting hours, however.
|$50,001 to $75,000
|No preference
|Never Married
|No preference
|Have kids:
|No preference
|Wants kids:
|No preference
|White / Caucasian
|No preference
I'm Irish predominately, and very proud.
|No preference
Was brought up with twelve years of catholic school, but no longer follow that path. I am respectful of all beliefs.
|No preference
|Some college
|No preference
I am just a few credits short of a BA from SFSU. I started working in my field in my final semester, and thanks the some admin errors I found out later I was a few credits short.


text:
- Tuesday 15 April 2014
- Monday 23 September 2013
- Oil and gas extraction will go ahead near the world's greatest desert river system - the Lake Eyre Basin rivers in Queensland's Channel Country. The State Government has confirmed it is winding back the Wild Rivers protection declarations in western Queensland. ...Wednesday 31 July 2013
- Tuesday 4 June 2013
- Thursday 30 May 2013
Explore by Topic
Latest Public Sector stories on ABC Western Queensland
Latest Public Sector stories on ABC Online
- Wednesday 1 July 2015
- During the last 6 months of 2014, tax payers footed the bill for more than $4.5 million to fit out electoral offices. Even some of the MPs think the spend was excessive....Tuesday 30 June 2015
- Tuesday 23 June 2015
- Are our political leaders willing to hear counter arguments or contrary advice if it runs against their political beliefs or interests? What's at risk if a government surrounds itself with too many yes men and women? And is politics the only place for a national conversation around policy and ...Sunday 21 June 2015
- 20 year old Luke has a problem with ice. We're following him as he tries to stop using....Friday 26 June 2015
Explore ABC Western Queensland by Topic
Latest videos
Latest audio
- Mark O'Brien talks about the success of cluster fencing in boosting sheep production
- Matt Peters, Kenton Peart and Trader Schmidt talk cattle prices in Charleville
- Members of the Qld Country Women's Association discuss their bus trip through drought stricken parts of the state
- Vendors, agents and the local mayor are pleased about the record price achieved at the Roma Saleyards
- Western Queensland grazier Pat Hegarty discussing wool prices

subset: commoncrawl


text:
Gustavo Dudamel Presents AMERICAS AND AMERICANS Hollywood Bowl Festival, 8/14-19
Inspired by the 2009/10 inaugural Americas and Americans festival at Walt Disney Concert Hall, Music Director Gustavo Dudamel presides over a new edition of the Americas and Americans festival at the Hollywood Bowl from Tuesday, August 14, 2012 to Sunday, August 19, 2012. In keeping with his long-standing belief that barriers can be broken through art, Americas and Americans brings to life Dudamel's global vision of a multi-cultural community unified by music.
"This festival is one that is meant to link us as a people so that borders dissolve, and we find those common threads and musical moments which unite North and South America as one. This is our music," says Dudamel.
The program for the Americas and Americans festival is as follows:
Tuesday, August 14, 2012, at 8pm
Los Angeles Philharmonic
Gustavo Dudamel, conductor
Juan Luis Guerra
MONCAYO Huapango
MÁRQUEZ Danzón No. 2
PIAZZOLLA La muerte del Ángel
VILLA-LOBOS Bachianas Brasileiras No. 4: Prelude
ABREU Tico-Tico
Juan Luis Guerra, who popularized the bachata and merengue genres from the Dominican Republic, is not only a successful musician who has accumulated countless awards from the Grammys, Billboard Awards and the Latin Billboard Awards, but he is also the Billboard Magazine Spirit of Hope award recipient for his untiring social and philanthropic efforts.
Wednesday, August 15, 2012, at 8pm
Rubén Blades
Eddie Palmieri Salsa Orchestra
Iconic Panamanian singer-actor-politician Ruben Blades makes his only West Coast appearance at the Hollywood Bowl performing with Puerto Rican pianist Eddie Palmieri and his Salsa Orchestra. He will be sharing the stage with Palmieri for the first time ever in North America.
Nine-time Grammy Award winner and Latin music icon Eddie Palmieri was recently distinguished as a 2013 National Endowment for the Arts Jazz Master, the nation's highest honor in Jazz. He joins the ranks of musical legends who have made major contributions to jazz, such as MiLes Davis, Ella Fitzgerald and George Benson.
Thursday, August 16, 2012, at 8pm
Los Angeles Philharmonic
Gustavo Dudamel, conductor
Sergio Tiempo, piano
NÚÑEZ Toccata Sinfónica No. 1
GINASTERA Piano Concerto No. 1
COPLAND Symphony No. 3
Making his professional debut at 14 at the Concertgebouw in Amsterdam, Sergio Tiempo has developed a reputation as one of the most individual and thought-provoking pianists of his generation. Born in Caracas, Venezuela, he performs regularly with fellow-countryman and friend Gustavo Dudamel including concerts with the Simón Bolívar Orchestra.
|Related Links
|Arizona Musicfest to Kick Off Jan 29; Roseanne Cash Headlines
December 22, 2014
About Author
- Casting Roundup: Sarah Chalke, Kim Raver Headline New Pilots
- ADVENTURE TIME Headed to the Big Screen?
- Pilot Season Roundup: Colm Feore, Daniel Stern, Dave Annable to Star in New Shows
- James Franco to Star in New Fox Comedy, WHY HIM?
- Christopher Meloni to Star in WGN America's Slave Drama UNDERGROUND
- Check Out Alex Dunphy's Full College Essay from Latest MODERN FAMILY Episode
- Photo Flash: HBO Reveals Key Art for GAME OF THRONES Season 5
- Syfy to Honor Leonard Nimoy with Special Programming This Sunday
- Grammy Winner Kelly Clarkson Exclusively Premieres New Music from New Album on MTV, VH1 & CMT First
- CONSTELLATIONS' Jake Gyllenhaal and Ruth Wilson Set for THEATER TALK This Weekend


text:
Reload the page and try again.
I have my own laptop, but, there was a time that it was damaged, so I was not able to use it. Depauw University has plenty of computers for students to use, however, the few problems that I can come up with are the availability of the computers and the networking reliability. The network/wifi in some areas of Depauw are really slow, and sometimes it is just hard to connect to.
pretty good for a university; the wifi goes out in certain areas but avoid those and you're fine. a lot of computers on campus but they still make you buy your own (preferably mac or hp).
They are present if you need them, but you couldnt survive without your own
Some days it's fast and reliable while others it lags and is glitchy.
There are plenty of computers but everyone should have their own, however there are tons of labs, tons of printers so you don't need your own and the wifi is fairly good.
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DePauw was recently named the third "most wired" university, and the campus is still planning more advancements. In fall 2005, DePauw developed a laptop initiative that required all incoming students to purchase a laptop through the University. The University offers discounted rates to students for the purchase of laptops. As much as this can be looked at in a negative way monetarily, this initiative has had a very positive impact on the campus. Students having their own computers means less students are fighting for space in labs and more students are able to work in a variety of locations on campus. Overall, it saves students lots of headaches, especially since DePauw has its own Help Desk on campus to help with any problems students may have with their laptops. And even though students are required to purchase laptops, public computer labs can still be found on campus. There are computer labs located in the Julian Science and Math Center, Roy O. West Library, and the Pulliam Center for Contemporary Media. These labs can be utilized by students for a variety of projects, from writing papers to editing videos for class.
Many students do complain about the cost of printing on university printers. The University charges 5 cents per page, and although they give students 400 pages free, some students think this is hardly enough. For most, however, 400 free pages is plenty, and five cents per page isn't all that much unless you are printing a large amount of work. Printers are plentiful around campus, and many students choose to bring their own printers to campus. In a pinch, it isn't hard to find a fellow student willing to help you out by printing off a paper.
Non-registered users are limited to 5 school profile page views per month.
Register for free to gain full access!


text:
We are glad to bring you to ringtones service Audiko.net, where it's possible to download free ringtones for your smart phone. Today we have a ringtone of "Stranger in Moscow" by Michael Jackson as well as 9064 other ringtones by Michael Jackson. "Stranger in Moscow" is one of the best tracks from the "HIStory: Past, Present and Future, Book 1 (disc 2: HIStory C" album that was made by Michael Jackson at their major label together with other 10 tracks. You can listen to all 35 Michael Jackson – "Stranger in Moscow" ringtone variations available here and download it for free in few seconds. You can also look at other 37 albums produced by Michael Jackson for all time. "Stranger in Moscow" is referred to Pop, and we bring you a huge amount of Pop melodies absolutely for free. And finally, we have collected lyrics for this track and you can view it here as well. So feel free to browse, listen, download ringtones at Audiko.net. Make your phone sound cool!
Michael Jackson - Stranger in Moscow
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- ΛΟΥΚΑΣ ΓΙΩΡΚΑΣ - Στην ουσία | FLY 89.7 νέο single | Loukas Giorkas - Stin ous


text:
Marshall Football Postgame Notes
Marshall 44, Ohio 14
Marshall Rolls Past Southern Miss 59-24
Herd racks up 629 yards of total offense
Postgame Notes
Marshall 59, Southern Miss 24
Daniel Finds Opportunity in Move to Rush Spot
The Word on the Herd-October 17, 2012
R-JUNIOR SEASON (2014): Played in all 14 games, getting two starts (Ohio, Akron) at "fox" (rush end) … Played 343 snaps in Herd defensive front four's 10-man rotation … Had 19 tackles (nine solos) with two tackles for loss and two forced fumbles, both against Ohio, when his four tackles were a personal season high … Emerged as contributor in spring practice.
R-SOPHOMORE SEASON (2013): Played in five games as backup … Had five tackles (two solos) … Scout Team member.
R-FRESHMAN SEASON (2012): Played in 10 games as backup … Posted 14 tackles (five solos) … Top game was three tackles (Western Carolina) … One tackle for loss, in his home state, at Purdue … Scout Team member.
FRESHMAN SEASON (2011): Redshirted.
HERD FILE: Born Aug. 16, 1991 …Majoring in Management at MU … At Avon High, posted 72 tackles, two interceptions, four forced fumbles and five pass breakups as a senior ... Recorded a total of 191 tackles, four interceptions, five forced fumbles and 15 pass breakups in his prep career ... Rated as a four-star player by ESPN … Rated as the No. 21 overall linebacker prospect in the nation by Rivals.com ... Also offered by Purdue, Illinois, Indiana, Cincinnati, Toledo and Western Kentucky … Older brother, Montez Robinson, played defensive line at Georgia.


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text: Everyone's favorite, lovable, and totally confusing music player / dancing speaker is coming to the States this spring. As we've extensively detailed, the odd little oval is packed with all kinds of zany abilities, not the least of which is playing MP3 or AAC files via Bluetooth with A2DP off of its 2GB (which is an improvement on the Japanese version's 1GB) of flash memory. No word on price right now, but you won't care once you see how darn cute the little guy is.


text:
The UK's fastest-growing regional news network
See the full forecast for your area.
Sponsored by Britelite.
Home Deal Sport Article
Chris Kinnear has urged everyone associated with Dover to leave their negativity at the Crabble doors as he has his sights set on a positive end to the season.
The Whites boss claims a feel-good spirit has returned to the dressing room on the back of consecutive 3-0 wins, firstly over FA Trophy finalists Gosport Borough at Crabble on Saturday and then at Skrill Premier side Dartford in the Kent Senior Cup quarter-final on Tuesday.
Whites are two points and two places outside the Skrill South play-off places ahead of Saturday's visit of Basingstoke, who are six points behind Dover with two games in hand.
Kinnear said remaining positive was key to Athletic's fortunes this season and insisted: "We always want to do well but the trick is that if you don't do well, don't let yourself get down, despondent and abusive – no good can come of that. It's just a downward spiral from there.
"If things don't go right, then we have to be realistic and try to put it right. It's important to keep a steady head."
He added: "Of course, the idea between now and the end of the season is to go on a winning run but if we have a blip, then we'll not get too down.
"Everyone is entitled to opinions, there is nothing wrong with that but you don't want them to have a negative effect. Negativity breeds negativity. You have to think of the consequences."
Full-back Tom Wynter is expected to be fit for Saturday after being forced off with a knee problem against Gosport.
Click here for more sport from Deal.
Click here for more news from around the county.


text:
Valentine's Day is close – along with Thanksgiving one of our favorite Holidays of the year. Reminding us to appreciate and honor the ones that matter most in our live – the people we love!!!
So in this spirit, we thought to maybe share an Engagement Portrait we recently took in Newport. Meet Sarah & Todd, a wonderful couple from New York City.
You might also enjoy
Heather & Mark
blessings, gratitude & image making
The Inn at Castle Hill with Lindsey & Crispin
Welcome Charlie!! First Portrait part 1
Share the beauty :)


text:
Ground-motion Attenuation and Earthquake Source Scaling in Eastern North America, Volume 1
Electric Power Research Institute, 1992 - Earth movements
From inside the book
18 pages matching km depth in this book
Where's the rest of this book?
Results 1-3 of 18
What people are saying - Write a review
We haven't found any reviews in the usual places.
Common terms and phrases
Appalachian attenuation curve attenuation in eastern Barney body waves Bollinger Brunswick earthquake Bull central Mississippi Valley central Virginia comparison of synthetic Conrad discontinuity constant stress drop continental interior corner frequency crust crustal model crustal structure crustal velocity models CSD model distance range drop scaling relation Dyersburg dyne-cm earth earthquake data Earthquake Source eastern North America EPRI Equality earthquake estimates Figure focal mechanism Gazli Geophys Giles County Goodnow Grenville ground motion attenuation Hampshire earthquake increasing stress drop J. B. Fletcher km depth Lg waves Madrid seismic zone magnitudes Mississippi embayment modei model of Nuttli Moho discontinuities motion attenuation relations North American earthquakes northeastern United Power Research Institute quakes RAY DECOMPOSITIONS refraction region relation of Nuttli Saint Louis University scaling relation Seis Seism shape source depth source duration source mechanism source parameters spectral stress drop scaling strong ground motion synthetic seismograms teleseismic tion variations in crustal veiocities wave propagation


text:
State to break ground on new psychiatric hospital
BERLIN — Vermont state officials are preparing to break ground, or — since it's January — break snow on a new state psychiatric hospital in Berlin.
Construction of the Green Mountain Psychiatric Care Center — a 25-bed facility next to the Central Vermont Medical Center — is to begin with a ceremony Tuesday afternoon.
The facility is to be the centerpiece of the state's efforts to replace the Vermont State Hospital in Waterbury. That antiquated facility, which state officials had talked of closing for years, finally had to shut down following flooding from Tropical Storm Irene in late
August 2011.
State officials hope to have the Berlin facility open by early next year.MORE IN This Just InMONTPELIER Vermonts Division of Fire Safety says public fireworks displays put on by trained... Full StoryMONTPELIER A Vermont state trooper has been honored for rescuing an 82-year-old woman from her... Full StoryMONTPELIER Vermont specialty food producers took home gold at this weeks Summer Fancy Food... Full Story
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text:
A multiple-exposure fluorescent image tracking velocimeter (FITV) detects and measures the motion (trajectory, direction and velocity) of small particles close to light scattering surfaces. The small particles may follow the motion of a carrier medium such as a liquid, gas or multi-phase mixture, allowing the motion of the carrier medium to be observed, measured and recorded. The main components of the FITV include: (1) fluorescent particles; (2) a pulsed fluorescent excitation laser source; (3) an imaging camera; and (4) an image analyzer. FITV uses fluorescing particles excited by visible laser light to enhance particle image detectability near light scattering surfaces. The excitation laser light is filtered out before reaching the imaging camera allowing the fluoresced wavelengths emitted by the particles to be detected and recorded by the camera. FITV employs multiple exposures of a single camera image by pulsing the excitation laser light for producing a series of images of each particle along its trajectory. The time-lapsed image may be used to determine trajectory and velocity and the exposures may be coded to derive directional information.
1. Apparatus for determining the flow field of a fluid near a fluid confining wall of a transparent body, said apparatus comprising:
a plurality of neutrally buoyant fluorescent particles suspended in the fluid;
a source of pulsed monochromatic light for directing a monochromatic light beam on the fluid and the confining wall for illuminating said fluorescent particles at predetermined time intervals, wherein said monochromatic light beam has a frequency λ1 capable of exciting said particles to a pulsed state of fluorescence at a frequency λ2 ;
filter means for receiving light scattered from said confining wall having said frequency λ1 and said fluorescent light having said frequency λ2 and for removing said scattered light and passing said fluorescent light; and
optical means cooperating with said filter means for receiving pulsed fluorescent light from said excited fluorescing particles having a frequency λ2 and for tracking displacement of said fluorescent particles in the fluid over time in providing a velocity map of said particles in the fluid adjacent to the confining wall of the body.
2. The apparatus of claim 1 wherein said source of pulsed monochromatic light includes a pulsed copper-vapor laser.
3. The apparatus of claim 1 wherein said source of pulse monochromatic light includes a continuous argon laser in combination with an acousto-optic modulator.
4. The apparatus of claim 1 further comprising beam shaping optics disposed intermediate said source of pulsed monochromatic light and the fluid and the fluid confining wall for converting a circular cross section of said monochromatic light beam to a light beam having a rectangular cross section and a large aspect ratio and for directing said rectangular cross section light beam onto the fluid and fluid confining wall.
5. The apparatus of claim 4 wherein said beam shaping optics includes at least one cylindrical lens.
6. The apparatus of claim 1 wherein said source of pulsed monochromatic light includes an acousto-optic modulator for converting said monochromatic light to a coded light pulse sequence to provide particle displacement direction information in said velocity map.
7. The apparatus of claim 1 wherein said particles include a fluorescent dye.
8. The apparatus of claim 7 wherein said particles are comprised of fluorescent dyed polystyrene latex having a size of 30�2 microns.
9. The apparatus of claim 1 wherein said filter means includes a thin film dielectric interference filter.
10. The apparatus of claim 1 wherein said filter means includes a Raman holographic edge filter.
11. The apparatus of claim 1 wherein said filter means includes a colloidal Bragg diffraction filter.
12. The apparatus of claim 1 wherein said optical means includes a tube camera in combination with an analog-to-digital converter for digitizing an analog output from said tube camera in providing a digital representation of the fluorescent light from the particles.
13. The apparatus of claim 12 wherein said optical means further includes a computer controlled parallel image processor.
14. The apparatus of claim 1 wherein said transparent body is an artificial implantable heart pump.
15. The apparatus of claim 14 further comprising a cardiac flow simulator coupled to said heart pump for providing the fluid thereto over a range of operating conditions corresponding to various patient hemodynamic conditions.
16. The apparatus of claim 1 wherein said transparent body is an artificial lung.
17. Apparatus for viewing and recording a flow field of a fluid in a transparent artificial heart assist pump adjacent a fluid-confining wall in said heart assist pump, said apparatus comprising:
a plurality of fluorescent particles in the fluid, wherein said particles are neutrally bouyant in the fluid and are approximately the size of human blood cells;
a source of pulsed monochromatic light for directing a monochromatic light beam having a frequency λ1 on the fluid and the fluid-confining wall for exciting said particles whereupon said particles emit fluorescent light having a frequency λ2, and wherein said monochromatic light beam is scattered by the fluid-confining wall;
a cardiac flow simulator coupled to the heart assist pump for providing the fluid thereto under various conditions representing a range of human heart operating circumstances;
an optical filter for receiving scattered light at a frequency λ1 and particle emitted fluorescent light at frequency λ2, wherein said optical filter removes the scattered light and transmits the fluorescent light; and
an optical detector and analyzer combination for receiving the pulsed fluorescent light via said optical filter from said fluorescent particles for providing an image tracking velocity map of the particles adjacent to the fluid-confining wall of the heart assist pump.
The United States Government has rights in this invention pursuant to the employer-employee relationship of the Government to the inventor as a U.S. Department of Energy employee at the Pittsburgh Energy Technology Center.
This invention relates generally to the analysis of fluid flow through a fluid carrying body and is particularly directed to observing and measuring flow fields in confined areas and particularly adjacent to surfaces such as the flow of blood or a blood simulation fluid bounded by a wall of biomaterial.
The Institute of Medicine recently estimated that between 35,000 and 70,000 Americans annually require either permanent circulatory assist devices or cardiac transplantation. For these patients, the therapy of choice remains cardiac transplantation. However, the donor heart supply is severely limited (1,673 cardiac transplants were performed in the United States in 1989) and is expected to remain so into the foreseeable future. Thus, development of circulatory assist devices is critical to the survival of most of these heart-failure patients.
For the last 25 years, much of the work to develop circulatory assist devices has involved pulsatile pumps that mimic the pumping action of the natural heart. Impressive progress has been made in solving the complex problems associated with the safe delivery of blood to the systemic circulation. In fact, several systems are now successfully being used to support terminal cardiac patients who await transplantation. One such device, the Novacor left ventricular assist system (LVAS), has been used to support more than 100 heart-failure patients awaiting transplantation. FIG. 1 is a simplified diagnostic illustration of a LVAS shown implanted in a patient. LVAS 10, employed as a temporary bridge to cardiac transplantation, is coupled to the left ventricle 12 of a human heart 14 and includes an inflow conduit 16, an outflow conduit 18, and a pump/drive unit 20. Respective inflow and outflow valves are located at the connection of the inflow and outflow conduits 16, 18 to the heart's left ventricle 12, although these valves are not shown in the figure for simplicity. LVAS 10 is disposed below the user's diaphragm 22, with the inflow and outflow conduits 16, 18 passing through the diaphragm. Incorporated in LVAS 10 is a microprocessor-based controller for regulating the pumping of blood within the pump/drive unit 20.
Blood-biomaterial interactions are of critical importance to the operation of the LVAS implant. Undesirable formation of thrombus on biomaterial surfaces can lead to critical, sometimes fatal, results. This activation is likely a strong function of patient-dependent factors and the choice of biomaterials, but fluid-dynamic properties of the device are also of great importance. Although the conditions that cause activation are not completely understood, it is believed that high shear rates, areas of flow stasis, and generation of strong recirculation zones are undesirable within any blood contacting device. Understanding fluid flow within the LVAS implant is essential for improving its performance in increasing survivability and enhancing the health of implant users.
The present invention is a significant advance in the area of artificial organs in that it permits observing and measuring in great detail flow fields within an artificial organ such as a LVAS implant and in particular near the biomaterial surfaces within the artificial organ. The present invention has also been successfully applied to analyze flow within the Nimbus AXIPUMP (another type of LXAS) and a type of artificial lung called an intravenous membrane oxygenator. Although disclosed primarily in terms of the analysis of blood flow within an artificial implant organ, the present invention is not limited to this environment, but is equally applicable for the analysis, measurement and recording of fluid flow fields in virtually any transparent fluid transporting device or system.
Accordingly, it is an object of the present invention to observe, measure and record the flow field in a fluid carrying device.
It is another object of the present invention to visualize, measure and quantify the blood flow field in an artificial implant organ such as a heart pump or a lung to determine blood-biomaterial interaction.
A further object of the present invention is to provide a detailed analysis of the flow field in a confined volume and in particular adjacent to and on the fluid confining surfaces.
Yet another object of the present invention is to monitor the flow field in an artificial heart pump under different operating modes to determine optimum heart pump operation for various patient conditions.
A still further object of the present invention is to observe the flow field in an implantable artificial organ under conditions that closely simulate clinically observed hemodynamic conditions of an implanted patient.
It is another object of the present invention to provide flow visualization information about large areas in a fluid transport device such as an artificial blood pump at one time to permit detailed analysis of complex geometries with moving boundaries and imperfect optical surfaces typical of the blood-pump sac.
It is yet another object of the present invention to provide not only a good qualitative view of flow patterns based on moving images in a fluid carrying device, but also to provide numerical values of velocity, shear rate and residence time with suitable illumination and data acquisition techniques.
These objects of the present invention are achieved and the disadvantages of the prior art are eliminated by apparatus for determining the flow field of a fluid near the fluid confining wall of a transparent body. The apparatus comprises a plurality of neutrally buoyant fluorescent particles suspended in the fluid and a source of pulsed monochromatic light for directing a monochromatic light beam on the fluid and on the confining wall for illuminating the fluorescent particles at predetermined time intervals, wherein the monochromatic light beam has a frequency λ1 capable of exciting the particles to a state of fluorescence at a frequency λ2. The apparatus further includes an optical filter for receiving light scattered from the confining wall having a frequency λ1 and fluorescent light having a frequency λ2 and for removing the scattered light and passing the fluorescent light and an optical analyzer cooperating with the filter for receiving pulsed fluorescent light from the particles having a frequency λ2 and for tracking displacement of the fluorescent particles in the fluid over time in providing a velocity map of the particles in the fluid adjacent to the confining wall of the body.
The appended claims set forth those novel features which characterize the invention. However, the invention itself, as well as further objects and advantages thereof, will best be understood by reference to the following detailed description of a preferred embodiment taken in conjunction with the accompanying drawings, where like reference characters identify like elements throughout the various figures, in which:
FIG. 1 is a simplified diagrammatic illustration of an artificial blood pump implanted in a human body and attached to that person's heart;
FIG. 2 is a simplified schematic diagram of a flow analysis system illustrating the basic concept of the fluorescent image tracking velocimeter of the present invention;
FIG. 3 is a simplified combined block and schematic diagram of a fluorescent image tracking velocimeter in accordance with the principles of the present invention;
FIG. 4 is a graphic representation of the excitation and emission spectra of a typical commercial fluorescent-dyed particle used in the present invention;
FIG. 5 is a graphic illustration of the transmission characteristics in the form of transmission spectra for notch and step filters employed in the present invention;
FIG. 6 is a simplified schematic diagram of a cardiac simulation flow loop directing a fluid through an artificial heart pump for analysis by the fluorescent image tracking velocimeter of the present invention;
FIG. 7 is an example of a fluorescent image tracking velocimeter image taken 10 milliseconds after the start of systole;
FIG. 8 is an example of a fluorescent image tracking velocimeter image taken by the present invention near the middle of diastole;
FIGS. 9a-9d illustrate the flow vectors around the inflow valve of an artificial heart pump as measured by the fluorescent image tracking velocimeter of the present invention with identical artificial heart pump output (3.3 l/min), but at different beat rates and stroke volumes; and
FIG. 10 is a graphic illustration of fluid speed within 1.5 mm of the surface of the inflow valve of an artificial heart pump averaged over three time samples as measured by the fluorescent image tracking velocimeter of the present invention.
The present invention employs a technique called fluorescent image tracking velocimetry, or FITV. FITV is a particle image velocimetry technique that enables measurements very close to biomaterial surfaces in accordance with the present invention.
With advances in computer imaging equipment and pulsed lasers, applications of particle image velocimetry are increasing rapidly. Another reason for the popularity of particle imaging velocimetry is its simplicity: a fluid is seeded with particles that follow the fluid flow--that is, neutrally-buoyant particles with low Stokes numbers and sizes much smaller than the length scales of the flow. A simplified schematic diagram of a flow analysis system 30 employing FITV as used in the present invention is shown in FIG. 1. A source of monochromatic light with a frequency λ1 such as a pulsed laser 32 illuminates the seeded flow field in a fluid 34 at controlled intervals. The displacement of particles 38 between laser pulses produces a velocity vector map of a flow field. From this, other important parameters, such as shear stress and particle residence time, are attainable.
A wall 36 of the fluid carrying body provides a confining surface 36a for the fluid 34. Light from the pulsed laser 32 at a frequency λ1 is scattered by the particles as well as by the confining surface 36a. The fluorescent particles 38, activated by the laser 32, emit light at a frequency λ2. An excitation filter 40 removes the λ1 light allowing only the λ2 light to reach a camera 42.
Although the underlying concept of particle imaging velocimetry appears to be straightforward, considerable problems must be addressed and resolved. The main difficulties are in the acquisition of images with good signal-to-noise (S/N) ratios near flow boundaries and the digital analysis of images.
There are many variations of particle imaging velocimetry. A double-pulse technique is known as particle image velocimetry or PIV. PIV produces a two-dimensional velocity map at an instant. The double-pulse technique has good spatial resolution but derives only the speed and orientation of velocity vectors--direction (sign) is unknown. A coded pulse sequence is one way to eliminate directional ambiguity. However, pulse coding often requires longer exposures and more pulses. This reduces spatial resolution due to the increased number and size of particle images. Yet another particle imaging velocimetry approach uses continuous pulsed illumination to produce Lagrangian trackings of particles through a flow field.
Refractive/reflective light scattering is adequate for most particle imaging applications. With enough illumination power, good signal-to-noise (S/N) ratios between particle images and the background are achievable. Near solid flow boundaries, however, the S/N ratio may diminish to the point that particle images are undetectable. This is because scattering (refractive/reflective scattering will simply be referred to as scattering) from solid flow boundaries is usually much stronger than from small particles. Even if the refractive indices of the fluid and flow boundary are matched, impurities in the solid flow boundary can still generate strong scattering.
The use of fluorescent particles and color filtering is one way to enhance S/N ratios near flow boundaries. When excited with light of an appropriate wavelength, the dye fluoresces or emits light. An important property of the fluorescent dye is its Stokes shift--the difference between excitation and emission wavelengths. Thus, the light from the particle shown in FIG. 2 consists of both scattered light at the excitation wavelength (λ1) and fluoresced light at a different wavelength (mean fluorescent emission, λ2). The light scattered by the flow boundary in FIG. 2 is at the same wavelength as the excitation light.
The S/N ratio is increased dramatically by placing an excitation filter 40 in front of the camera 42. The excitation filter 40 occludes the light scattered by the flow boundary and the particle at λ1 --the camera sees only the fluorescent light emitted by particles at λ2. This has provided excellent S/N ratios of particles close to biomaterial surfaces such as in a LVAS.
Referring to FIG. 3, there is shown a simplified combined schematic and block diagram of a fluorescent image tracking velocimeter (FITV) 50 in accordance with the principles of the present invention. FITV 50 includes a pulsed excitation source such as either a pulsed copper-vapor laser 52 or a copper-vapor continuous argon laser 52 in combination with an acousto-optic modulator 54. The pulsed laser beam is directed through beam shaping optics such as a pair of cylindrical lenses 56 for converting the beam into a rectangular cross section with a large aspect ratio known as a laser sheet 58 and then sent to an artificial heart pump 60 for flow analysis of a fluid therein. An electronic camera 64 with a digital image acquisition system detects and records the particle velocity image within the artificial heart pump 60 through an excitation occlusion filter 62 which screens out the excitation wavelengths and passes only the fluorescent wavelengths. An image processing computer system 66 including a parallel image processing subsystem 68 processes and analyzes the FITV images. Each of these components of FITV 50 is described in greater detail in the following paragraphs.
Excitation Light Sources. The wavelength of the light source should be close to the peak excitation wavelength of the fluorescent dye. The excitation light source must produce pulsed light with accurate and controllable pulse timing. Continuous emission lasers with an acousto-optical modulator are ideal. Experience indicates that at least 1 watt of power is necessary for FITV.
For this application, the excitation source is preferably either an argon or a copper-vapor laser. The argon laser produces up to 5 watts of continuous light with the most powerful wavelengths (nm) at 488 (blue) and 514.5 (green). Other less powerful lines are present at wavelengths from 350 nm to 507.1 nm.
An electronically controlled acousto-optic modulator (AOM) pulses the continuous beam of the argon laser. The AOM transmission rise time limits the AOM pulse capabilities. With a rise time of less than 50 ns, the AOM pulses can range from continuous transmission to repetition rates over 1 MHz and pulse durations less than a microsecond.
The copper-vapor laser is pulsed with pulse durations of 30 ns and repetition rates of up to 20 KHz. Pulse energies range from 0.5 to 2 mJ. The copper-vapor laser produces two primary wavelengths of 510.6 and 578.2 nm with a total average optical power of 10 W. Only the 510.6 nm wavelength is used for this application. The copper-vapor laser is used only if the required pulse durations become short enough that the pulse energies from the argon laser drop well below 0.5 mJ.
Beam shaping optics. The beam shaping optics consist of a series of cylindrical lens 56. They transform the circular cross section of the beam into a rectangular cross section with a large aspect ratio. This is commonly called a laser sheet 58.
Fluorescent-Dyed Particles Fluorescent particles are available from several commercial manufacturers. Some of the commercial manufacturers are Polyscience, Duke Scientific, and Bangs laboratories. FIG. 4 is a graphic illustration of the excitation and emission characteristics of a commercial fluorescent particle. The dye in this particle is suitable for excitation with the green wavelengths of argon (514.5 nm) and copper-vapor (510.6 nm) lasers. Other fluorescent-dyed particles are available for excitation with lasers of different wavelengths.
Excitation Filters. The purpose of the excitation filter 62 is to occlude the excitation wavelength(s) and pass the fluorescent wavelengths. With monochromatic excitation, the ideal filter will block only a single wavelength. Three types of filters approach monochromatic occlusion: thin-film dielectric interference filters, Raman holographic edge (RHE) filters, and colloidal Bragg diffraction filters. The mean occlusion characteristics of the interference and RHE filters are practically the same. The transmission characteristics of an RHE and a colloidal filter are shown in FIG. 5.
Since the Stokes shift is significant ('20 nm) for many fluorescent dyes, an edge filter can possibly be used. Edge filters are much less expensive than the notch filters. FIG. 5 also shows the transmission curve of an inexpensive edge filter.
Image acquisition system. The camera employed in this embodiment of FITV 50 is a MTI Model 81 tube camera. The camera scanning parameters are externally controlled through an ANDROX programmable video controller 68. An ANDROX analog-to-digital converter (ADC) digitizes the analog output of the MTI 81. With this setup, image resolutions from 512�512 pixels to 2048-1800 pixels are attained. The grey-level resolution of each pixel is 8 bits. The frame rate is variable from 10 frames per second (2048�1800 pixel resolution) to 100 frames per second (512�512 pixel resolution).
Image processing computer system. Processing and analysis of FITV images are done on a SUN 470 workstation equipped with an ANDROX parallel image processing subsystem. The ANDROX system accelerates many image processing functions by a factor of 50 or more over the SUN 470 CPU.
Referring back to FIG. 1, the artificial heart pump 10 is placed extraperitoneally within the abdomen, with the inflow conduit 16 connected to the left ventricular apex. The outflow conduit 18 may be anastomosed to either the abdominal aorta as shown in the figure, or to the thoracic aorta. Because the artificial heart pump 10 receives its inflow from the left ventricle, inflow rates are highly variable depending on the contractile status of the myocardium. In the immediate post-operative period, the contractility of the diseased myocardium is additionally depressed by anaesthetic agents. Under these conditions, the ventricle functions almost as a passive conduit and therefore the LVAS inflow is relatively constant. However, because the LVAS allows the myocardium to deliver flow at a greatly reduced afterload, myocardial contractile function may recover and increase beyond pre-implant values within a few days. The ventricle then acts as a "priming pump" for the LVAS, and the inflow to the LVAS becomes markedly pulsatile with peak flow rates of as much as four to five times greater than the immediate post-operative values.
It is essential to acquire the FITV images under representative patient conditions, including varying degrees of myocardial contractility. For this purpose, an active mock loop 70 shown in simplified schematic diagram form in FIG. 6 has been designed. Inflow to the LVAS 80 is provided by a servo-controlled piston pump 72 coupled to and driven by the combination of a servo-amplifier and computer control 74. This control combination permits the piston pump 72 to produce an arbitrary flow waveform based on a voltage command. Using a programmable waveform generator, it is possible to generate LVAS inflow waveforms that accurately mimic inflows monitored from patients in an operating room or intensive-care unit.
Flow patterns in the LVAS 80 are also a function of the afterload presented to it. The LVAS afterload in this mock loop uses a calibrated preload compliance 94 coupled to a "venous" reservoir 92 to simulate the systemic vascular compliance and a pneumatic pressure regulator 90 to maintain the mean arterial pressure within physiological values independent of flow, just as occurs in the body via the baroreceptor reflex. The mock loop is instrumented with an ultrasonic transit-time flowmeter 76 and clinical pressure transducers 78 and 86 are coupled to the inflow and outflow valves 82 and 84, respectively, of the LVAS 80. An afterload compliance 88 is coupled between the LVAS output valve 84 and pressure regulator 90, while polyurethane check valves 75 and 96 couple the piston pump 72 respectively to the LVAS 80 and to the preload compliance 94.
The LVAS 80 was manufactured from transparent materials to provide optical access for FITV. A transparent blood analog fluid which has a viscosity close to that of blood (4 cps) was also used. The blood analog fluid consists of a solution of 42% wt. aqueous spectrophotometric-grade glycerin.
The blood analog fluid was seeded with "red" fluorescent particles manufactured by Duke Scientific. The particles consist of polystyrene latex and a proprietary mixture of fluorescent dyes. They are neutrally buoyant and their size is 30�2 microns.
Several filters were tested for the present application. These included an RHE filter and several inexpensive step filters. Rather than attempting an independent measurement of optical density, the performance parameter (S/N ratio) pertinent to this application was measured under typical operating conditions.
The test consisted of measuring the S/N ratios produced with the FITV system for a fixed, representative scene. The scene was a pericardial trileaflet valve in its transparent housing filled with blood analog fluid. The housing, pericardial valve, and blood analog fluid are the same as used in actual flow measurements. The only experimental variable was the type of excitation filter placed in front of the camera lens. The valve is constructed of bovine heart tissue formed into three flexible leaflets that open and close to restrict flow to one direction. The valve leaflet material was found to have mild fluorescent properties. This is undesirable since it increases the background level. Dying the valve with a black clothing dye practically eliminates the valve's fluorescence.
The flow conditions for FITV measurements simulated the full range of clinical conditions typically observed for cardiac transplant patients: pump rates ranged from 60 to 120 beats/minute with fill volumes ranging from 25 to 60 cc.
During a cardiac cycle, the FITV system acquires six images at fixed time separations. For example, if the cardiac cycle duration were 600 ms, six measurements are made at 100 ms separations. After digitizing six images into video RAM, the images are compressed and stored on the SUN 470 hard disk. The acquisition and storage of six FITV images takes about 20 seconds. For a specific experimental condition, data is acquired for at least 100 cardiac cycles.
FIGS. 7 and 8 show two examples of typical FITV images. FIG. 7 is taken at the beginning of the systole: the flow velocities are high because valve flaps are in motion (closing). FIG. 8 is taken near mid-diastole when the valve flaps are not moving (fully open) and the velocities are much lower. Consequently, to maintain reasonable spacings between consecutive particle images, the laser pulse frequency is varied from frame-to-frame throughout the cardiac cycle. For example, the pulse frequency in FIG. 7 is 1 KHz and in FIG. 8 it is 222 Hz.
Referring to FIGS. 9a-9d, there are shown representations of the flow vectors around the inflow valve of an artificial heart pump for four cases with identical heart pump output (3.3 l/min), but with differing heart rates and stroke volumes. A unit vector of 10 cm/sec is shown in each figure. The valve stents are shown in outline in solid line form in these figures. The lengths of the flow vectors indicate the local speed and the angle of flow is indicated by the vector angle. The flow vectors derived from particle images shown in FIGS. 9a-9d exhibit an ambiguity with respect to the sense of flow direction, i.e., up versus down, left versus right. This ambiguity is due to the symmetric pulse coding of the illumination source. Directional sense can be determined and displayed by a suitable pulse coding technique such as a long pulse of light followed by a series of shorter pulses. Such pulse trains are easily implemented using the electrically-driven acousto-optical modulator described above and a computer-programmed pulse generator. Pulse coding has been successfully implemented for analysis of flow in an artificial lung device.
Effective washing of the prosthetic surfaces within the artificial heart pump is a function of the local shear rates which are, in turn, determined by the fluid velocities. Because the shear rates in this region are much lower than in the valve proper, where the whole stroke volume is forced through a narrow orifice, excessive shear (and consequent application of platelets) is likely less of an issue than the avoidance of stasis. From FIGS. 9a-9d and FIG. 10 which illustrates the variation of fluid speed versus heart pump rate, where fluid speed within 1.5 mm of the surface of the inflow valve has been averaged over the three time instances sampled and where error bars indicate standard deviation, it can be seen that the fluid speed in the vicinity of the inflow valve increases with increasing heart pump beat rate and not with stroke volume under the conditions tested. Maximum speed increases more rapidly than does mean or minimum speed as the beat rate is increased, but the significance of this in terms of stasis is unclear. These data suggest that the flow associated with opening and closing of the inflow valve leaflets is of more importance in the washing of the adjacent areas than is the volume of fluid passing through the valve during each pump cycle. Preliminary studies confirm this finding for the outflow valve area also.
There has thus been shown a fluorescent image tracking velocimeter for visualizing and measuring flow fields adjacent to a fluid confining surface which is particularly adapted for blood flow diagnosis in artificial implantable organs such as a heart pump or lung. Visualization of flow fields adjacent to the biomaterial surfaces in confined areas employs small, neutrally buoyant fluorescent tracer particles for feature extraction. The fluorescent particles are illuminated by a monochromatic laser light source and a filter is used to remove background scattering light before it reaches a scanning camera. Particle motion can then be tracked using parallel image processing software and calculations made of velocities, shear rates and particle residence times in various regions of interest within the artificial implantable organ. Flow measurements can be made under a wide range of conditions simulating the situations observed clinically of both rapid and slow pump filling, including low rates of pump filling typical of the immediate post-operative period which is of critical importance. Other operating modes which can be studied using the fluorescent image tracking velocimeter include (1) internally-triggered automatic synchronous counterpulsation, (2) ECG-triggered synchronous operation, (3) full-to-empty or (4) fixed rate asynchronous operation and an extensive variety of patient hemodynamic conditions.
While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects. Therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention. The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only and not as a limitation. The actual scope of the invention is intended to be defined in the following claims when viewed in their proper perspective based on the prior art.
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Originally written on The Penalty Flag | Last updated 2/5/13
Pittsburgh Steelers fans nearly had their prayers answered when a power surge caused a partial power failure during the third quarter of the Super Bowl. However the failure only lasted approximately 15 minutes. When action resumed, despite a valiant effort by the San Francisco 49ers, the Baltimore Ravens managed to hold on and win their second title in team history. Much to the chagrin of their AFC rivals Pittsburgh Steelers. Starting in 2013, one thing that is certain is the Steelers have some unfinished business to attend to... Read more
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