Skip to main content

Home/ science/ Group items tagged Direct

Rss Feed Group items tagged

Skeptical Debunker

Human cells exhibit foraging behavior like amoebae and bacteria - 0 views

  • "As far as we can tell, this is the first time this type of behavior has been reported in cells that are part of a larger organism," says Peter T. Cummings, John R. Hall Professor of Chemical Engineering, who directed the study that is described in the March 10 issue of the Public Library of Science journal PLoS ONE. The discovery was the unanticipated result of a study the Cummings group conducted to test the hypothesis that the freedom with which different cancer cells move - a concept called motility - could be correlated with their aggressiveness: That is, the faster a given type of cancer cell can move through the body the more aggressive it is. "Our results refute that hypothesis—the correlation between motility and aggressiveness that we found among three different types of cancer cells was very weak," Cummings says. "In the process, however, we began noticing that the cell movements were unexpectedly complicated." Then the researchers' interest was piqued by a paper that appeared in the February 2008 issue of the journal Nature titled, "Scaling laws of marine predator search behaviour." The paper contained an analysis of the movements of a variety of radio-tagged marine predators, including sharks, sea turtles and penguins. The authors found that the predators used a foraging strategy very close to a specialized random walk pattern, called a Lévy walk, an optimal method for searching complex landscapes. At the end of the paper's abstract they wrote, "...Lévy-like behaviour seems to be widespread among diverse organisms, from microbes to humans, as a 'rule' that evolved in response to patchy resource distributions." This gave Cummings and his colleagues a new perspective on the cell movements that they were observing in the microscope. They adopted the basic assumption that when mammalian cells migrate they face problems, such as efficiently finding randomly distributed targets like nutrients and growth factors, that are analogous to those faced by single-celled organisms foraging for food. With this perspective in mind, Alka Potdar, now a post-doctoral fellow at Case Western Reserve University and the Cleveland Clinic, cultured cells from three human mammary epithelial cell lines on two-dimensional plastic plates and tracked the cell motions for two-hour periods in a "random migration" environment free of any directional chemical signals. Epithelial cells are found throughout the body lining organs and covering external surfaces. They move relatively slowly, at about a micron per minute which corresponds to two thousandths of an inch per hour. When Potdar carefully analyzed these cell movements, she found that they all followed the same pattern. However, it was not the Lévy walk that they expected, but a closely related search pattern called a bimodal correlated random walk (BCRW). This is a two-phase movement: a run phase in which the cell travels primarily in one direction and a re-orientation phase in which it stays in place and reorganizes itself internally to move in a new direction. In subsequent studies, currently in press, the researchers have found that several other cell types (social amoeba, neutrophils, fibrosarcoma) also follow the same pattern in random migration conditions. They have also found that the cells continue to follow this same basic pattern when a directional chemical signal is added, but the length of their runs are varied and the range of directions they follow are narrowed giving them a net movement in the direction indicated by the signal.
  •  
    When cells move about in the body, they follow a complex pattern similar to that which amoebae and bacteria use when searching for food, a team of Vanderbilt researchers have found. The discovery has a practical value for drug development: Incorporating this basic behavior into computer simulations of biological processes that involve cell migration, such as embryo development, bone remodeling, wound healing, infection and tumor growth, should improve the accuracy with which these models can predict the effectiveness of untested therapies for related disorders, the researchers say.
thinkahol *

First 'living' laser made from kidney cell - physics-math - 12 June 2011 - New Scientist - 0 views

  •  
    It's not quite Cyclops, the sci-fi superhero from the X-Men franchise whose eyes produce destructive blasts of light, but for the first time a laser has been created using a biological cell. The human kidney cell that was used to make the laser survived the experience. In future such "living lasers" might be created inside live animals, which could potentially allow internal tissues to be imaged in unprecedented detail. It's not the first unconventional laser. Other attempts include lasers made of Jell-O and powered by nuclear reactors (see box below). But how do you go about giving a living cell this bizarre ability? Typically, a laser consists of two mirrors on either side of a gain medium - a material whose structural properties allow it to amplify light. A source of energy such as a flash tube or electrical discharge excites the atoms in the gain medium, releasing photons. Normally, these would shoot out in random directions, as in the broad beam of a flashlight, but a laser uses mirrors on either end of the gain medium to create a directed beam. As photons bounce back and forth between the mirrors, repeatedly passing through the gain medium, they stimulate other atoms to release photons of exactly the same wavelength, phase and direction. Eventually, a concentrated single-frequency beam of light erupts through one of the mirrors as laser light.
Erich Feldmeier

Vlastimil Hart: Frontiers in Zoology | Abstract | Dogs are sensitive to small variation... - 0 views

  •  
    "We measured the direction of the body axis in 70 dogs of 37 breeds during defecation (1,893 observations) and urination (5,582 observations) over a two-year period. After complete sampling, we sorted the data according to the geomagnetic conditions prevailing during the respective sampling periods. Relative declination and intensity changes of the MF during the respective dog walks were calculated from daily magnetograms. Directional preferences of dogs under different MF conditions were analyzed and tested by means of circular statistics. Results Dogs preferred to excrete with the body being aligned along the North-south axis under calm MF conditions. This directional behavior was abolished under Unstable MF. The best predictor of the behavioral switch was the rate of change in declination, i.e., polar orientation of the MF. "
anonymous

Horizontal Drilling, How Directional Drillers Drill Oil Wells Sideways - 0 views

  •  
    How horizontal oil and gas wells are drilled with directional drilling techniques.
thinkahol *

Politics and eye movement: Liberals focus their attention on 'gaze cues' much different... - 0 views

  •  
    In a new study, researchers measured both liberals' and conservatives' reaction to "gaze cues" -- a person's tendency to shift attention in a direction consistent with another person's eye movements. Liberals responded strongly to the prompts, consistently moving their attention in the direction suggested to them by a face on a computer screen. Conservatives, on the other hand, did not
thinkahol *

Quantum physics first: Physicists measure without distorting - 1 views

  •  
    With this new experiment, the researchers have succeeded for the first time in experimentally reconstructing full trajectories which provide a description of how light particles move through the two slits and form an interference pattern. Their technique builds on a new theory of weak measurement that was developed by Yakir Aharonov's group at Tel Aviv University. Howard Wiseman of Griffith University proposed that it might be possible to measure the direction a photon (particle of light) was moving, conditioned upon where the photon is found. By combining information about the photon's direction at many different points, one could construct its entire flow pattern ie. the trajectories it takes to a screen.
thinkahol *

First Direct Photo of Alien Planet Finally Confirmed | KurzweilAI - 1 views

  •  
    A planet outside of our solar system, said to be the first ever directly photographed by telescopes on Earth, has been officially confirmed to be orbiting a sun-like star that is 500 light-years away.
Janos Haits

Web History, a timeline - 0 views

  •  
    A timeline of the history of the World Wide Web Key dates, browsers, technologies and ideas in the history of the World Wide Web. Originally compiled by John Allsopp from Web Directions we welcome your suggestions.
Janos Haits

ScienceWISE - Scientific Web-based Interactive Semantic Environment - 0 views

  •  
    The ScienceWISE.info provides scientists with possibilities of article annotation and scientific bookmarking, helping the international community of physicists to generate dynamically, as a part of their everyday work, an interactive semantic environment, containing a field specific concept ontology with direct ..
Kayla Davis

Netflix download App: Addition to Netflix original movie list is "The Discovery" - 0 views

  •  
    Netflix makes addition in its original movies list with "The Discovery", which is a sci-fi love story directed by Charlie McDowell and will be premier in 2017.
Dave James

Manage Your Monetary Difficulty Without Difficulty Via Online - 0 views

  •  
    If you are going through lack of cash difficulty and you do not have money to manage with it, same day loans are perfect way for you to acquire trouble free cash advance without any trouble at emergency time. Acquire bother free cash direct into your valid bank account without any difficulty during emergency time.
Janos Haits

Starry Messenger - 0 views

  •  
    The Starry Messenger is Phase I of the Electronic History of Astronomy developed in the Whipple Museum of the History of Science and the Department of History and Philosophy of Science. This phase was directed by Dr Sachiko Kusukawa and Dr Liba Taub, and supported by funding from Trinity College, Cambridge. Dr David Chart was the Project Manager.
meenatanwar

Bike Rent in Haridawr - 0 views

  •  
    We can do online and direct booking for cars, scooters and bikes for vacations and holidays.
thinkahol *

Berkeley Lab scientists open electrical link to living cells | KurzweilAI - 0 views

  •  
    Scientists with the Lawrence Berkeley National Laboratory (Berkeley Lab) have designed an electrical link to living cells engineered to shuttle electrons across a cell's membrane to an external acceptor along a well-defined path. This direct channel could yield cells that can read and respond to electronic signals, electronics capable of self-replication and repair, or efficiently transfer sunlight into electricity.
thinkahol *

Video games: Racing, shooting and zapping your way to better visual skills - 0 views

  •  
    According to a new study in Current Directions in Psychological Science, a journal of the Association for Psychological Science, regular gamers are fast and accurate information processors, not only during game play, but in real-life situations as well.
The Ravine / Joseph Dunphy

Neave Planetarium ...the sky in your web browser - 0 views

  •  
    It's a cute graphic, but not much more than that. You move the cursor and the simulated night sky moves in response - and it's a great example of how the Internet can take us in the wrong direction. Do you remember kids getting books and ... gasp ... going outdoors at night, looking upward and finding those constellations, instead of searching for them on an animation?
Charles Daney

BBC - Spaceman: Still waiting to bag the big one - 0 views

  •  
    It was supposed to be the first great scientific discovery of the 21st Century - or so many researchers thought when they rushed down to the bookmakers to place bets at what were deemed at the time to be ludicrously generous odds. The physicists believed that they were close to making the first direct detection of gravitational waves, the ripples in space-time generated by supernovas and coalescing neutron stars.
thinkahol *

Foxes zero in on prey via Earth's magnetic field - life - 12 January 2011 - New Scientist - 0 views

  •  
    It sounds like something a guided missile would do. Foxes seem to zero in on prey using Earth's magnetic field. They are the first animal thought to use the field to judge distance rather than just direction.
Infogreen Global

The nature of the electromagnetic field inside of nano-sized hotspots - 0 views

  •  
    Because the size of these metallic hotspots is far smaller than the wavelength of incident light, a new technique was needed to map the electromagnetic field within a hotspot. The Berkeley researchers developed the BEAST method to capitalize on the fact that individual fluorescent dye molecules can be localized with single nanometer accuracy. The fluorescence intensity of individual molecules adsorbed on the surface provides a direct measure of the electromagnetic field inside a single hotspot. BEAST utilizes the Brownian motion of single dye molecules in a solution to make the dyes scan the inside of single hotspot stochastically, one molecule at a time.
thinkahol *

New driving force for chemical reactions - 1 views

  •  
    ScienceDaily (June 9, 2011) - New research just published in the journal Science by a team of chemists at the University of Georgia and colleagues in Germany shows for the first time that a mechanism called tunneling control may drive chemical reactions in directions unexpected from traditional theories.
1 - 20 of 37 Next ›
Showing 20 items per page