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Wednesday, February 27, 2013
Star Trek Trumps Mythology in Naming Pluto's New Moon
Tuesday, February 26, 2013
Hummingbird flight: Two vortex trails with one stroke
Feb. 25, 2013 ? As of today (February 25), the Wikipedia entry for the hummingbird explains that the bird's flight generates in its wake a single trail of vortices that helps the bird hover. But after conducting experiments with hummingbirds in the lab, researchers at the University of California, Riverside propose that the hovering hummingbird instead produces two trails of vortices -- one under each wing per stroke -- that help generate the aerodynamic forces required for the bird to power and control its flight.
The results of the study could find wide application in aerospace technology and the development of unmanned vehicles for medical surveillance after natural disasters.
The researchers used high-speed image sequences -- 500 frames per second -- of hummingbirds hover-feeding within a white plume (emitted by the heating of dry ice) to study the vortex wake from multiple perspectives. They also used particle image velocimetry (PIV), a flow-measuring method used in fluid mechanics, to quantitatively analyze the flow around the hummingbirds. PIV allowed the researchers to record the particles surrounding the birds and extract velocity fields.
The films and velocity fields showed two distinct jets of downwards airflow -- one under each wing of the hummingbird. They also revealed that vortex loops around each jet are shed during each upstroke and downstroke.
The researchers therefore propose in their paper published online last month in the journal Experiments in Fluids that the hummingbird's two wings form bilateral vortex loops during each wing stroke, which is advantageous for maneuverability.
"Previous studies have indicated that slow-flying bats and faster flying birds produced different structures in their wakes," said Douglas Altshuler, formerly an assistant professor of biology at UC Riverside, whose lab led the research. "We have been investigating the wake structure of hovering hummingbirds because this allows us to decouple the effects of different types of wings -- bat versus bird -- from different forward flight speeds.
Hummingbirds each weigh 2-20 grams. Because they can hover with high precision, they are able to drink nectar from flowers without any jiggling movement to their bodies. Besides using upstrokes and downstrokes, hummingbirds can rotate their wings. They can even flap their wings from front to back with a 180-degree amplitude.
"We began this study to investigate how the hummingbird used its tail while hovering," said Marko Princevac, an associate professor of mechanical engineering and a coauthor of the research paper. "After all, many insects also hover, but they have no tail. Instead, however, our research showed something interesting about the hummingbird's wings: the bilateral vortex structure. Hummingbirds hovering should cost a lot of energy but these birds are able to hover for long periods of time. Ideally, unmanned vehicles need to be operated with a very limited energy supply, which is why understanding how the hummingbird maximizes its use of energy is tremendously beneficial."
Sam Pournazeri, a former Ph.D. graduate student in Princevac's lab and a co-author on the paper, explained that in a downstroke, the air pressure difference developed as a result of wing movement creates flow from the bottom to the top of the wing. The result is a circular movement or vortex.
"Based on theories in fluid mechanics, this vortex should close either on the wing/body or create a loop around it," he said. "It's these loops that provide circulation around the wings and cause the hummingbird to overcome its weight. Hovering requires the bird to create a lift that cancels its body weight. Although the two-vortex structure we observed increases the hummingbird's energy consumption, it provides the bird a big advantage: a lot more maneuverability."
Next, the research team plans to study the hummingbird in a wind tunnel to closely observe how the bird transitions from hovering to forward motion, and vice versa.
"Current technology is not successfully mimicking how living things fly," Princevac said. "Drones don't hover, and must rely on forward motion. Research done using hummingbirds, like ours, can inform the development of the next generation of drones."
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Story Source:
The above story is reprinted from materials provided by University of California - Riverside. The original article was written by Iqbal Pittawala.
Note: Materials may be edited for content and length. For further information, please contact the source cited above.
Journal Reference:
- Sam Pournazeri, Paolo S. Segre, Marko Princevac, Douglas L. Altshuler. Hummingbirds generate bilateral vortex loops during hovering: evidence from flow visualization. Experiments in Fluids, 2012; 54 (1) DOI: 10.1007/s00348-012-1439-5
Note: If no author is given, the source is cited instead.
Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.
Source: http://feeds.sciencedaily.com/~r/sciencedaily/~3/mX8jP5brUZY/130225153139.htm
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Doctors take Harper government to court over refugee health-care cuts
By?Obert Madondo?|?The Canadian Progressive, Feb. 25, 2013:
Jason Kenney, Canada?s Immigration Minister
Canadian refugee lawyers, advocacy groups, doctors and patients are banding together to file a lawsuit ?against the Harper government?s recent draconian cuts to health care for refugees. The group from the?Canadian Association of Refugee Lawyers (CARL), ?Canadian Doctors for Refugee Care (CDRC), and three individual patients, says the?cuts violate the fundamental rights of refugees as protected by the Canadian Charter of Rights and Freedoms.
The group is asking the Federal Court of Canada to declare the cuts unconstitutional and illegal.
?The cuts violate the fundamental human rights of refugees,? the group said in a statement issued Friday.??They cause unwarranted sufferings to countless individuals, and unnecessary costs to the Canadian health care system.?
The cuts were implemented through the Conservatives? Bill C-31, the so-called ?Protecting Canada?s Immigration System Act?, which passed in Parliament last June and came into effect on December 15, 2012.
The Canadian Medical Association Journal has warned that the cuts?pose?serious mental health risks for refugees. Daniel Garcia Rodriguez, a refugee applicant,?almost went blind?as a result of the cuts.?Other experts have argued that the bill will not give refugees a fair chance to tell their stories.
After the bill passed, Jewish-American political activist, Nobel laureate, writer, professor, Elie Wiesel, joined tens of thousands of Canadians who vocally condemned the cuts.
?I feel morally compelled to remain on the side of other uprooted men and women everywhere.?Today, as yesterday, a nation is judged by its attitude towards refugees,? said the?Holocaust survivor.
The majority of the refugees severely impacted are persons of color and trauma survivors, two facts Conservatives seem to be unmoved by.
Just after the bill passed, its architect and Minister of Citizenship and Immigration, Jason Kenney, posted a petition on his personal website?asking Canadians to thank him for a job well done.
?We, the undersigned, thank Jason Kenney for his efforts to streamline benefits afforded to refugees claimants under the Interim Federal Health Program (IFHP) and bring them in line with the benefits received by tax-paying Canadians, including new Canadians,? the petition said.
The House of Commons? Standing Committee on Public Safety and National Security?recently?recommended?the?use of electronic ankle bracelets?on failed refugee claimants to keep a tab on their movements. The committee is?chaired by?Conservative MP Kevin Sorenson.
Last October, Kelly Block, the Conservative MP for Saskatoon-Rosetown-Biggar, ?celebrated? Jason?s cuts with a?flyer?mailed to members of her riding.
?New arrivals to Canada have received dental and?vision care paid by your tax dollars. They?ve had free prescriptions. Not anymore,? the flyer read.
In the House of Commons, Official Opposition NDP called on Block to apologize. ?She is bragging about denying medication for kidney disease to an elderly woman or?care to a young woman who is 18 weeks pregnant due to a sexual assault,? ?said Jinny?Sims, the NDP MP for Newton-North Delta in B.C. ?This flyer is offensive and misleading.?Will the member apologize??
The Canadian Progressive recommends:
Obert Madondo is the founder and publisher of The Canadian Progressive. He?s a fearless and passionate activist, progressive political blogger, writer, journalist, public speaker and publisher. He?s worked as speechwriter to Margaret Dongo, a former Independent Zimbabwean MP. He's worked as a senior international development executive with the Konrad Adenauer Foundation, a Germany international development agency, and with a Canadian charity. Obert is published or quoted here: The Huffington Post, CBC News, Ottawa Citizen, The Canadian Progressive, Toronto Sun, Rabble.ca, Metro News, The Charlatan, EMC Kanata, The Dominion, Ground Report, AfricaFiles & New Zimbabwe
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10 Things to Know for Monday
Palestinians throw stones during clashes with Israeli troops in the West Bank city of Hebron, following the death of Arafat Jaradat, a Palestinian prisoner held in an Israeli jail, Sunday, Feb. 24, 2013. The death of a 30-year-old Palestinian after interrogation by Israel's Shin Bet security service stokes new West Bank clashes, along with Israeli fears of a third Palestinian uprising. (AP Photo/Nasser Shiyoukhi)
Palestinians throw stones during clashes with Israeli troops in the West Bank city of Hebron, following the death of Arafat Jaradat, a Palestinian prisoner held in an Israeli jail, Sunday, Feb. 24, 2013. The death of a 30-year-old Palestinian after interrogation by Israel's Shin Bet security service stokes new West Bank clashes, along with Israeli fears of a third Palestinian uprising. (AP Photo/Nasser Shiyoukhi)
Host Seth MacFarlane speaks onstage during the Oscars at the Dolby Theatre on Sunday Feb. 24, 2013, in Los Angeles. (Photo by Chris Pizzello/Invision/AP)
Your daily look at late-breaking news, upcoming events and the stories that will be talked about Monday:
1. SPREADING THE BLAME FOR BUDGET CUTS
The White House and Republicans kept up the mudslinging over who's to blame for $85 billion in budget cuts set to take effect this week.
2. 'ARGO' WINS BEST PICTURE OSCAR, 'LIFE OF PI' NETS MOST AWARDS
The CIA thriller won three Oscars, while "Life of Pi" won four trophies, including best director for Ang Lee.
3. OSCARS HOST GETS A VISIT FROM CAPT. KIRK
Seth MacFarlane's show opener included a celestial skit with Star Trek's William Shatner.
4. CONCERNS OF NEW PALESTINIAN UPRISING
The mysterious death of a Palestinian man in Israeli custody comes at a time of rising West Bank tensions.
5. AN ESCAPE CLAUSE FOR VOTING RIGHTS LAW
Obama and civil rights groups are defending the landmark law at the Supreme Court by pointing to a clause that allows reformed governments to bail out.
6. WHO'S USING CAPTURED TANKS IN NEW OFFENSIVE
Syrian rebels are employing the armor in an attempt to capture a government complex on the outskirts of Aleppo.
7. WHAT POPE BENEDICT SAID IN HIS FINAL SUNDAY BLESSING
The pontiff said God had called him to dedicate himself "even more to prayer and meditation," which he will do in a monastery.
8. HOW A FLORIDA COMMUNITY HAS CHANGED AFTER A SHOOTING
A year after Trayvon Martin was killed, leaders in Sanford have established a community relations panel to help ease racial tensions.
9. ANOTHER PISTORIUS CHARGED IN SOUTH AFRICA
The older brother of Oscar Pistorius was charged in a 2008 fatal traffic accident.
10. JIMMIE JOHNSON CRUISES TO 2ND DAYTONA 500 WIN
Danica Patrick also made history as the first woman to lead the race, but finished eighth.
Associated PressTunisia: 4 in custody for politician's murder
TUNIS, Tunisia (AP) ? Tunisia's interior minister said Tuesday that four suspects belonging to a radical Islamist group are being held for their involvement in the murder of a leftist opposition politician earlier this month that plunged the country into a political crisis.
Ali Larayedh said the suspects, some of whom had been arrested in the last 48 hours, were just accomplices to the murder and did not include the assassin himself, who remains at large and subject to a manhunt.
The suspects range in age from 26 to 34 years old and are part of a "radical religious group," the minister said, adding that one had confessed to accompanying the actual assassin.
Chokri Belaid was shot four times outside his home on the morning of February 6, provoking widespread rioting around the country as many held the government responsible for his death.
Belaid's assassination resulted in the resignation of the country's prime minister and Larayedh has been appointed his successor to form a new coalition government.
Thousands demonstrated on Sunday, protesting the lack of progress in solving the crime, which was seen as a symptom of the increasing violence in Tunisia's politics.
Since the overthrow of the country's secular dictatorship in January 2011, there has been a rise in ultraconservative Muslims known as Salafis, some of whom have resorted to violence.
Authorities have also discovered numerous weapons caches and clashed with militants crossing into the country from neighboring Algeria and Libya.
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Saturday, February 23, 2013
Twitter implements DMARC standard to fight phishing
News
Twitter users are constantly targeted in phishing attacks that try to pass rogue emails as official communications from the company. These phishing emails direct users to fake Twitter websites in order to steal their login credentials.
?Earlier this month, we began using a new technology called DMARC that makes it extremely unlikely that most of our users will see any email pretending to be from a Twitter.com address. DMARC is a relatively new security protocol created by a group of organisations to help reduce the potential for email-based abuse,? said Josh Aberant, Twitter?s postmaster, Thursday in a?blog post.
DMARC, short for ?Domain-based Message Authentication, Reporting & Conformance,? is a standard for implementing the SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail) email message validation and authentication systems.
The technologies can be used to verify that an email with a sender address of, for example, twitter.com actually came from servers authorized to send email on behalf of twitter.com. The goal of DMARC is to achieve a uniform implementation of these systems among the top email services providers and other companies that would benefit from email validation.
DMARC is supported by all four major email providers ? Google (Gmail), Microsoft (Outlook.com/Hotmail), Yahoo (Yahoo Mail) and AOL. It has also been implemented by services like Facebook, PayPal, Amazon and now Twitter.
While Twitter?s support for DMARC will help email providers block messages with forged @twitter.com addresses from reaching the inboxes of many users, it won?t prevent phishing emails that masquerade as Twitter communications but have non-twitter.com sender addresses. This means that users should remain vigilant and scrutinise all details of emails received from Twitter before acting on their instructions.
DMARC celebrated its one-year anniversary earlier this month, but according to DMARC.org, the industry group that oversees the standard?s development and adoption, it already helps protect 60 percent of the world?s email boxes from spam and phishing. More than 325 million spoofed messages were rejected in November and December 2012 because leading email providers and email senders implemented DMARC, the group?said on its website.
Source: http://www.macworld.com.au/news/twitter-implements-dmarc-standard-to-fight-phishing-87657/
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'The Invisible War? brings attention to rape in the military
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Source: http://news.yahoo.com/oscar-nominated-documentary-invisible-war-brings-attention-rape-120528968.html
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