Treatment leads to near-normal life expectancy for people with HIV in South Africa

Apr. 9, 2013 ? In South Africa, people with HIV who start treatment with anti-AIDS drugs (antiretroviral therapy) have life expectancies around 80% of that of the general population provided that they start treatment before their CD4 count drops below 200 (cells per microliter), according to a study by South African researchers published in this week's PLOS Medicine.

These findings are encouraging and show that with long-term treatment, HIV can be managed as a chronic illness in middle- and low-income settings, and also suggest that the estimates used by life insurance companies and epidemiological modellers may need to be revised -- these estimates typically assume that life expectancy after starting antiretroviral therapy is around 10 years.

The researchers, led by Leigh Johnson from the University of Cape Town, reached these conclusions by collecting information from six HIV treatment programs throughout South Africa between 2001 and 2010, which they then used in a survival model.

The authors found that -- as in HIV-negative adults -- the most significant factor determining the life expectancy of patients starting HIV treatment was their age when they started treatment: the average life expectancy (additional years of life) of men starting antiretroviral therapy varied between 27.6 years at age 20 and 10.1 years at age 60, while corresponding estimates in women were 36.8 and 14.4 years, respectively.

They also found that life expectancies were significantly influenced by baseline CD4 counts (a measure of the strength of the immune system at the time of starting treatment): life expectancies in patients with baseline CD4 counts of 200 cells per microliter or more were between 70% and 86% of those of HIV negative adults of the same age and sex, while patients starting antiretroviral therapy with CD4 counts of less than 50 cells per microliter had life expectancies that were between 48% and 61% of those of HIV-negative adults.

The study also showed that the risk of death was highest during the first year after starting antiretroviral treatment, because of the delay between the start of treatment and the recovery of the immune system. Life expectancies were typically 15-20% higher two years after starting treatment than at the time of starting treatment. For example, in patients who started treatment with CD4 counts of more than 200 cells per microliter, life expectancies two years after starting therapy were between 87% and 96% of those in HIV-negative individuals (compared to a range of 70-86% at the time of starting treatment).

Although these results are encouraging, this study also highlights that many HIV patients are still starting treatment with very low CD4 counts, and health services must overcome major challenges, such as late diagnosis, low uptake of CD4 testing, loss from care, and delayed antiretroviral therapy initiation, if near-normal life expectancies are to be achieved for the majority of people with HIV in South Africa.

The authors also cautioned that their results were based on projections of the low mortality rates observed after patients had been on treatment for a few years, and that there was uncertainty about how mortality rates might change in future, particularly at longer treatment durations. The authors noted that although there was the promise of new drugs and new patient management strategies, which might reduce mortality further, there was also the risk of rising levels of HIV drug resistance, which might compromise treatment effectiveness.

The authors say: "These results have important implications for the pricing models used by life insurance companies, as well as the demographic and epidemiological models that are used to forecast the impact and cost of [antiretroviral therapy] programmes in low- and middle-income countries."

They continue: "Assumptions of longer life expectancy would significantly reduce the forecasts of AIDS mortality, but would also significantly increase long-term projections of numbers of patients receiving [antiretroviral therapy]."

The authors add: "It is therefore critical that appropriate funding systems and innovative ways to reduce costs are put in place, to ensure the long-term sustainability of [antiretroviral therapy] delivery in low- and middle-income countries."

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The above story is reprinted from materials provided by Public Library of Science.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

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Journal Reference:

1. Leigh F. Johnson, Joel Mossong, Rob E. Dorrington, Michael Schomaker, Christopher J. Hoffmann, Olivia Keiser, Matthew P. Fox, Robin Wood, Hans Prozesky, Janet Giddy, Daniela Belen Garone, Morna Cornell, Matthias Egger, Andrew Boulle. Life Expectancies of South African Adults Starting Antiretroviral Treatment: Collaborative Analysis of Cohort Studies. PLoS Medicine, 2013; 10 (4): e1001418 DOI: 10.1371/journal.pmed.1001418

Note: If no author is given, the source is cited instead.

Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.

Source: http://feeds.sciencedaily.com/~r/sciencedaily/~3/FhhmZ6i4N3c/130409173502.htm

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Gay attack victim in France becomes cause celebre

Wilfred de Bruijn, a Dutch citizen who lives and works as a librarian in Paris, France, gestures during an interview with The Associated Press at his apartment in Paris, Wednesday, April 10, 2013. De Bruijn was beaten unconscious near his home early Sunday morning in central Paris, sustaining 5 fractures in his head and face, abrasions and a lost tooth. After posting a photo of his wounds on Facebook, the image went viral and de Bruijn has become a national cause celebre of the pro-gay campaign. (AP Photo/Remy de la Mauviniere)

Wilfred de Bruijn, a Dutch citizen who lives and works as a librarian in Paris, France, gestures during an interview with The Associated Press at his apartment in Paris, Wednesday, April 10, 2013. De Bruijn was beaten unconscious near his home early Sunday morning in central Paris, sustaining 5 fractures in his head and face, abrasions and a lost tooth. After posting a photo of his wounds on Facebook, the image went viral and de Bruijn has become a national cause celebre of the pro-gay campaign. (AP Photo/Remy de la Mauviniere)

Wilfred de Bruijn, a Dutch citizen who lives and works as a librarian in Paris, France, speaks during an interview with The Associated Press at his apartment in Paris, Wednesday, April 10, 2013. De Bruijn was beaten unconscious near his home early Sunday morning in central Paris, sustaining 5 fractures in his head and face, abrasions and a lost tooth. After posting a photo of his wounds on Facebook, the image went viral and de Bruijn has become a national cause celebre of the pro-gay campaign. (AP Photo/Remy de la Mauviniere)

Wilfred de Bruijn, a Dutch citizen who lives and works as a librarian in Paris, France, speaks during an interview with The Associated Press at his apartment in Paris, Wednesday, April 10, 2013. De Bruijn was beaten unconscious near his home early Sunday morning in central Paris, sustaining 5 fractures in his head and face, abrasions and a lost tooth. After posting a photo of his wounds on Facebook, the image went viral and de Bruijn has become a national cause celebre of the pro-gay campaign. (AP Photo/Remy de la Mauviniere)

Wilfred de Bruijn, a Dutch citizen who lives and works as a librarian in Paris, France, shows a photo of his face shot by his friend after he was beaten, during an interview with The Associated Press at his apartment in Paris, Wednesday, April 10, 2013. de Bruijn was beaten unconscious near his home early Sunday morning in central Paris, sustaining 5 fractures in his head and face, abrasions and a lost tooth. After posting a photo of his wounds on Facebook, the image went viral and de Bruijn has become a national cause celebre of the pro-gay campaign. (AP Photo/Remy de la Mauviniere)

Wilfred de Bruijn, a Dutch citizen who lives and works as a librarian in Paris, France, gestures during an interview with The Associated Press at his apartment in Paris, Wednesday, April 10, 2013. De Bruijn was beaten unconscious near his home early Sunday morning in central Paris, sustaining 5 fractures in his head and face, abrasions and a lost tooth. After posting a photo of his wounds on Facebook, the image went viral and de Bruijn has become a national cause celebre of the pro-gay campaign. (AP Photo/Remy de la Mauviniere)

PARIS (AP) ? The shocking photo of a homophobic attack victim in Paris that went viral on social media this week and caused the French interior minister to weigh in was used as an emblem in a pro-gay rally Wednesday evening.

The image of Wilfred de Bruijn's cut and bruised face was brandished by gay groups during a demonstration of several thousand people as evidence of their claim that homophobic acts have tripled nationwide over opposition to a law legalizing gay marriage.

This week, the French senate will conclude its debate on a law legalizing same-sex marriage and adoption, which is expected to pass. It's been a rocky run since it was unveiled last November by President Francois Hollande's Socialists and split the majority-Catholic country.

But whichever way the Senate votes, the image of De Bruijn's battered face has made for a symbolic end to five months of bitterly divisive protests.

De Bruijn was beaten unconscious near his home early Sunday in central Paris, sustaining five fractures in his head and face, abrasions and a lost tooth. His boyfriend, who was also beaten up, said he witnessed three to four men shouting "Hey, look they're gays," before they attacked. The incident has shocked France, and garnered support far and wide as a gay "cause celebre." On Tuesday night, Interior Minister Manuel Valls called De Bruijn personally to express his shock.

"I certainly feel there's been an increase in homophobia," De Bruijn told The Associated Press at his apartment in Paris' working class 19th district, where the attack took place.

"What (the anti-gay marriage campaign) are saying is that they're not homophobic: lesbians and gays are nice people, but don't let them get close to children ? that's very dangerous. It's OK for them to live together, but not like other couples with the same protection because it's not really the same thing," De Bruijn said.

"These people are all professionals of the spoken word. They know very well what can happen if you repeat, repeat, repeat that these people are lower human beings. Of course it will have a result."

In light of the attack ? which has forced members of the anti-gay marriage campaign to defend themselves ? 30 gay associations organized the anti-homophobia rally for Wednesday. Associations SOS Homophobia and Refuge have used De Bruijn's case to highlight the spike they've recorded in homophobia since the gay marriage bill was announced last year. Both associations report that homophobic acts ? verbal and physical ? in the first three months of 2013 have tripled compared with the same period in 2012.

Meanwhile, Frigide Barjot, the stage name of an activist who has led protests against the bill, insisted the anti-gay marriage movement is opposed to violence. Speaking on RMC radio Wednesday, Barjot was careful to distance herself from a rightwing movement called the "French Spring," whose name was supposedly inspired by the revolutionary values of 2011's "Arab Spring."

"We don't want violence. We denounce this violence and these acts, we have nothing to do with (Catholic) fundamentalists or extremists," she said.

Not so, for De Bruijn.

"It was not Frigide Barjot who was hitting my head, or the bishop of Avignon lurking in that street to attack us," he said. "But they are responsible."

___

Thomas Adamson can be followed at Twitter.com/ThomasAdamsonAP

Associated Press

Source: http://hosted2.ap.org/APDEFAULT/cae69a7523db45408eeb2b3a98c0c9c5/Article_2013-04-10-France-Gay%20Attacks/id-2dfd0cb435834d419b74d71b8b87a304

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Settlement reached in 'Spider-Man' B'way musical

NEW YORK (AP) ? A settlement has been reached between the producers of "Spider-Man: Turn Off the Dark" and its fired director, Julie Taymor, ending a bitter legal fight that had marred what has become a Broadway success story.

"All claims between all of the parties in the litigation have been resolved," both sides said in a statement Wednesday. No details about the settlement or how it was reached were immediately revealed.

Taymor, who was the original "Spider-Man" director and co-book writer, was fired after years of delays, accidents and critical backlash.

The show, which features music by U2's Bono and The Edge, opened in November 2010 but spent months in previews before officially opening a few days after the Tony Awards in June. It has become a financial hit at the box office.

In November 2011, Taymor slapped the producers ? led by Michael Cohl and Jeremiah J. Harris ? as well as Glen Berger, her former co-book writer, with a federal copyright infringement lawsuit, alleging they violated her creative rights and haven't compensated her for the work she put into the $75 million show. The producers' filed a counterclaim asserting the copyright claims were baseless.

"We're happy to put all this behind us," said a statement by Cohl and Harris. For her part, Taymor was quoted in the release as saying: "I'm pleased to have reached an agreement and hope for the continued success of 'Spider-Man,' both on Broadway and beyond."

Taymor's lawsuit sought half of all profits, gains and advantages derived from the sale, license, transfer or lease of any rights in the original "Spider-Man" book along with a permanent ban of the use of her name or likeness in connection with a documentary film that was made of the birth of the musical without her written consent.

It also sought a jury trial to determine her share of profits from the unauthorized use of her version of the superhero story, which it said was believed to be in excess of $1 million.

Manhattan federal Judge Katherine Forrest had set a May 27 trial date after lawyers for Taymor asked that the case move forward because a settlement was never finalized. But that looming showdown is now off.

The legal wrangling revealed a behind-the-scenes atmosphere that was secretive and slightly paranoid. Taymor alleged that Berger was told to quietly work on changes to the story without Taymor's knowledge ? called "Plan X" ? that in an email Berger complained led him to lead a "double life" ? both working with and against Taymor.

The stunt-heavy show has been doing brisk business ever since it opened its doors and most weeks easily grossing more than the $1.2 million the producers have indicated they need to reach to stay viable.

Taymor had alleged that the show has not been re-imagined and that what audiences are seeing at the Foxwoods Theatre is essentially the same show she directed. "The producers' current suggestion that they have created a 'new' show after a mere three-week shutdown is false and incredible," the filing says.

After Taymor left, Philip William McKinley, who directed the Hugh Jackman musical "The Boy From Oz" in 2003, was hired to take over. He was billed as creative consultant when the musical opened.

When the show finally opened in June 2011, and Taymor received a standing ovation and kisses from cast members, as well as Bono and The Edge.

___

Follow Mark Kennedy on Twitter at http://twitter.com/KennedyTwits

Source: http://news.yahoo.com/settlement-reached-spider-man-bway-musical-153139234.html

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Rutgers commissioning review of basketball scandal

Rutgers University President Robert Barchi announces he accepted the resignation of athletic director Tim Pernetti, Friday, April 5, 2013, in New Brunswick, N.J. The Rutgers men's basketball scandal claimed two more university officials on Friday, including Pernetti and John B. Wolf, an interim senior vice president, who were involved in a decision to "rehabilitate" rather than fire basketball coach Mike Rice whose abusive behavior was captured on a video. On Thursday, assistant coach Jimmy Martelli resigned. Barchi's position appears to be safe. Pernetti dismissed Rice on Wednesday. (AP Photo/Mel Evans)

Rutgers University President Robert Barchi announces he accepted the resignation of athletic director Tim Pernetti, Friday, April 5, 2013, in New Brunswick, N.J. The Rutgers men's basketball scandal claimed two more university officials on Friday, including Pernetti and John B. Wolf, an interim senior vice president, who were involved in a decision to "rehabilitate" rather than fire basketball coach Mike Rice whose abusive behavior was captured on a video. On Thursday, assistant coach Jimmy Martelli resigned. Barchi's position appears to be safe. Pernetti dismissed Rice on Wednesday. (AP Photo/Mel Evans)

NEWARK, N.J. (AP) ? Rutgers University announced Monday that it's commissioning an independent review of the conduct of fired basketball coach Mike Rice and the way the university handled the situation when it learned that he was kicking and shoving players and berating them with gay slurs in practice.

The review ensures that the saga will not end quickly or quietly.

A video of Rice's behavior was made public last week, more than five months after it was given to the university, which initially decided to suspend the coach, fine him and send him to anger-management counseling.

After it became public, the university fired Rice. Athletic director Tim Pernetti resigned and so did a university lawyer who had advised him and an assistant basketball coach. Some faculty members and others have also called for university President Robert Barchi to step down, though he's received support from the school's Board of Governors and Gov. Chris Christie.

The scandal has prompted the FBI to investigate whether a former Rutgers basketball employee tried to extort money from the university before recording practices at which Rice was seen pushing and otherwise belittling players, a person familiar with the investigation told The Associated Press.

Rutgers said its Board of Governors will meet Thursday to discuss hiring the independent adviser to review the case.

Also Monday, board chairman Ralph Izzo said that one board member ? athletics committee chairman Mark P. Hershhorn ? had seen the video in December. Izzo said that it was not shown to other members and while the topic of the coach's conduct was discussed at a committee meeting in December, it was not discussed at the whole-board meeting that month. The university did not immediately respond to a request to interview Hershhorn.

On Monday, Barchi is scheduled to hold a town hall meeting that had been planned for last week but was postponed after a video surfaced showing Rice pushing players, throwing basketballs at them and berating them with invectives, including gay slurs.

The meeting was meant to address the sweeping plan to re-organize the state's higher education system, a priority of Gov. Chris Christie that the state legislature signed off on last year. The New Jersey Assembly will hold a budget hearing that will address the plan at the school Tuesday.

The goal, Barchi and state officials say, is to make Rutgers competitive with elite public institutions including the University of California, Berkeley, the University of Michigan and the University of Virginia. Strengthening the school would also bring in more tuition from out-of-state students who are charged more.

Barchi, a neurologist, was hired to help implement the transition and oversee a meshing of Rutgers and the state's University of Medicine and Dentistry. Some members of Rutgers' board of governors have expressed concern over the merger, because Rutgers would absorb $500 in the medical school's debt. The merger could cost up to $75 million, Barchi said in December.

Some say Barchi's plans for the university shortchange the school's campuses in Camden in Newark.

Rutgers has three campuses: Camden, Newark and New Brunswick. Faculty and students here fear that Barchi wants to turn New Brunswick ? where its sports teams are based, along with neighboring Piscataway? into a flagship campus, diverting resources from the other two. There is already a proposal to merge the Newark and Camden law schools and move strong research institutions to New Brunswick.

The three campuses have been designated with different missions: New Brunswick is research, Camden is service and Newark is diversity.

Diversity has been an important issue at Rutgers since the 2010 suicide of a student who learned his roommate had used a webcam to watch him kiss another man in his dorm. Faculty members calling for Barchi's ouster cited Rice's use of gay slurs in the video ? and the school president's decision not the fire Rice immediately ? as indicative of Barchi's lack of commitment to diversity.

Some critics claim Rutgers wants to minimize one of the nation's most diverse campuses.

"There is institutional antagonism toward minority students," said Beryl Satter, a professor of history at Rutgers-Newark.

Some here complained that under the restructuring law each campus will have a separate line item in the state budget, something that could potentially funnel funding away from Camden and Newark and to New Brunswick.

"It's like Robin Hood in reverse," Satter said.

Satter and other professors held their own town hall meeting Thursday after Barchi pulled out, urging students to attend a budget hearing Tuesday on the merger and speak up about cuts.

Satter is among the professors who have signed a petition calling for Barchi's job.

H. Bruce Franklin, the John Cotton Dana Professor of English and American Studies at Rutgers-Newark, signed the petition and worries that the merger may set off competition between the campuses, which have previously worked well together.

"They're siphoning off funds for big time athletics and other things in New Brunswick," Franklin said.

___

Associated Press reporter Geoff Mulvihill contributed to this report.

Associated Press

Source: http://hosted2.ap.org/APDEFAULT/386c25518f464186bf7a2ac026580ce7/Article_2013-04-08-Rutgers%20President/id-0910ebc58d834a72b76e4bec56d465c4

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Can Selenium Lower Risk of Advanced Prostate Cancer? - Health ...

By Amanda Gardner
HealthDay Reporter

TUESDAY, April 9 (HealthDay News) ? Men who have higher levels of the mineral known as selenium may also face a lower risk of developing advanced prostate cancer, new research suggests.

The authors of the study said the mineral ? found in foods such as Brazil nuts, in supplements and in foods grown in selenium-rich soil ? might one day offer a way to reduce prostate cancer risk in men.

?There is very little evidence on modifiable prostate cancer risk factors,? said study author Milan Geybels. ?Any compound that would prevent the incidence of advanced prostate cancer would have a substantial impact on public health.?

Geybels, who is a doctoral candidate in cancer epidemiology at Maastricht University in Maastricht, the Netherlands, was scheduled to present the findings Tuesday at the annual meeting of the American Association of Cancer Research, in Washington, D.C. Data and conclusions presented at medical meetings typically are considered preliminary until published in a peer-reviewed journal.

Still, the findings should not be construed as an endorsement of selenium supplements, experts warned.

?At this point, I wouldn?t recommend that all men run out and buy a bottle of selenium to take,? said Dr. Elise Cook, an associate professor of clinical cancer prevention at the M.D. Anderson Cancer Center in Houston.

Too much selenium can be toxic, resulting in skin problems, and may even be associated with an increased risk of diabetes, Cook said. Getting selenium from dietary sources, however, shouldn?t be a problem.

Cancer researchers have been interested in the supposed benefits of selenium on prostate cancer for years, until results from a large trial several years ago showed that selenium, taken either alone or with vitamin E, did not prevent prostate cancer.

?Before that, selenium supplements had been flying off the shelves,? said Dr. Alexander Kutikov, an associate professor of urologic oncology at Fox Chase Cancer Center in Philadelphia. ?Enthusiasm [for selenium] was really dampened by that trial.?

But that study looked at men with normal selenium levels when they entered the trial, and it did not focus on a specific type of prostate cancer. This latest study looked only at men who were deficient in selenium and tracked only cases of advanced prostate cancer, which is linked with a poor prognosis.

Among a group of almost 60,000 men aged 55 to 69 at the beginning of the study, the researchers found that men with the highest selenium levels, as measured in toenail clippings, had more than a 60 percent reduced risk for advanced prostate cancer.

Selenium levels in toenail clippings indicate long-term selenium intake, the researchers noted. The large trial from several years ago measured blood levels of the mineral, which reflects only recent exposure.

Still, the study is ?hypothesis-generating at best,? Kutikov said. Although the findings suggested an association between selenium levels and advanced prostate cancer risk, they did not prove a cause-and-effect link.

Geybels said the results could point the way to another trial assessing risk for advanced prostate cancer in men with low selenium levels.

More information

The U.S. National Cancer Institute has more on prostate cancer.

Source: http://news.health.com/2013/04/09/can-selenium-lower-risk-of-advanced-prostate-cancer/

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96% War Witch

All Critics (46) | Top Critics (16) | Fresh (44) | Rotten (2)

Canadian writer-director Kim Nguyen spent nearly a decade researching this docudrama about child soldiers in Africa, and the film feels as authoritative as a first-hand account.

A haunting take on unspeakably grim subject matter, shot on location in the Democratic Republic of Congo.

A powerful and upsetting portrait of a young girl compelled into unimaginably horrific circumstances.

Nguyen, astonishingly, manages to wring something vaguely like a happy ending from this tragic story.

War Witch is most effective not when we are looking in on Komona but when we are inside her head.

The powerful things we expect from "War Witch" are as advertised, but what we don't expect is even better.

You're likely to remember its images, its insights into a very foreign (for most of us) location and the tragic situation of Komona and others like her for a long time to come.

Is it accurate depiction of Africa's child soldiers? I don't know, thank God. But it feels authentic to its very core, and that makes it as hard to forget as it is to ignore.

Brutal without turning exploitative, the result is harrowing and heartbreaking.

Nguyen creates a mesmerizing tone through his camerawork, editing, sound and the infusion of African folk imagery and ritual, but it's Mwanza's performance as Komona that makes "War Witch" feel so miraculous.

Nguyen reportedly worked on "War Witch" for a decade, and it shows in both the immediacy and authenticity of his tale, and the meticulous craft with which it's told.

Made with extremely clear-eyed restraint from harangues, sentiment, message-mongering, or anything else that would cheapen its central character's suffering and fight.

War Witch features a standout performance by Rachel Mwanza, but the supernatural visions don't really suit the film's tone and mood.

Nguyen's compassion and commitment to the issue is admirable, and at its best, War Witch is devastating.

War Witch is remarkable for the fact that it never strays into sentimentality or sensationalism.

...a love story between youngsters who are forced to become adults all too early in their lives.

This is a straight ahead essay on warfare at its worst and the survival of the human spirit at its best.

An astonishing drama set in Africa that vividly depicts the courage and resiliency of a 12-year-old girl whose spiritual gifts enable her to survive.

It is astonishing that film that contains such violence can have such a serene tone. The source of the serenity is the measured, calm narration by Komona (voice of Diane Umawahoro) that is the telling of her story to her unborn child

An exquisitely made film in direct contrast to the ugliness of its subject matter

The portrait of a girl who retains her dignity and strength, her faith in the future, in the face of unimaginable horrors. It's inspirational in a very real way.

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Source: http://www.rottentomatoes.com/m/war_witch/

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NASA taps the power of zombie stars in two-in-one instrument

Apr. 8, 2013 ? Neutron stars have been called the zombies of the cosmos. They shine even though they're technically dead, occasionally feeding on neighboring stars if they venture too close. Interestingly, these unusual objects, born when a massive star extinguishes its fuel and collapses under its own gravity, also may help future space travelers navigate to Mars and other distant destinations.

NASA recently selected a new mission called the Neutron-star Interior Composition Explorer (NICER) to not only reveal the physics that make neutron stars the densest objects in nature, but also to demonstrate a groundbreaking navigation technology that could revolutionize the agency's ability to travel to the far reaches of the solar system and beyond.

The multi-purpose mission, also known as NICER/SEXTANT (Station Explorer for X-ray Timing and Navigation Technology), consists of 56 X-ray telescopes in a compact bundle, their associated silicon detectors, and a number of other advanced technologies. Both NASA's Science Mission Directorate's Explorers Program and the Space Technology Mission Directorate's Game Changing Program are contributing to the mission's development.

"It's rare that you have an opportunity to fly a cross-cutting experiment," said Principal Investigator Keith Gendreau, a scientist at NASA's Goddard Space Flight Center in Greenbelt, Md., who is leading NICER/SEXTANT's development. "The time is right for this experiment. This is one that we can do now."

In addition to NASA Goddard scientists and engineers, the mission team includes the Massachusetts Institute of Technology and commercial partners, who are providing spaceflight hardware. The Naval Research Laboratory and universities across the United States, as well as in Canada and Mexico, are providing science expertise.

Space Station Bound

Slightly larger than a typical college dormitory refrigerator, NICER/SEXTANT will be deployed on the International Space Station (ISS) in 2017. It will fly as an external attached payload on one of the ISS ExPRESS Logistics Carriers, unpressurized platforms used for experiments and storage.

The X-ray instrument's primary objective is to learn more about the interior composition of neutron stars, the remnants of massive stars that, after exhausting their nuclear fuel, exploded and collapsed into super-dense spheres about the size of New York City. Their intense gravity crushes an astonishing amount of matter -- often more than 1.4 times the content of the sun or at least 460,000 Earths -- into these city-sized balls, creating the densest objects known in the universe. Just one teaspoonful of neutron star matter would weigh a billion tons on Earth.

"A neutron star is right at the threshold of matter as it can exist -- if it were compressed any further, it would collapse completely in on itself and become a black hole," said Zaven Arzoumanian, a NASA Goddard scientist serving as the deputy principal investigator on the mission. "We have no way of creating or studying this matter in any laboratory. There are many theories about what it is and how it behaves, but the only way to test our models and understand what happens to matter under such incredible pressures is to study neutron stars," he added. "The closest we come to simulating these conditions is in particle accelerators that smash atoms together at almost the speed of light. However, these collisions are not an exact substitute -- they only last a split second, and they generate temperatures that are much higher than what's inside neutron stars."

Although the nuclear-fusion fires that sustained their parent stars are extinguished, neutron stars still shine with heat left over from their explosive formation, and from radiation generated by their magnetic fields that became intensely concentrated as the core collapsed.

Although neutron stars emit radiation across the spectrum, observing in the X-ray band offers the greatest insights into their structure, the ultimate stability of their pulses as precise clock "ticks," and the high-energy, dynamic phenomena that they host, including starquakes, thermonuclear explosions, and the most powerful magnetic fields known in the universe.

NICER's 56 telescopes will collect X-rays generated from its tremendously strong magnetic field and from hotspots located at the stars' two magnetic poles. At these locations, the intense magnetic field emerges from the surface. Particles trapped in the magnetic field rain down and generate X-rays when they strike the surface. As the hotspots rotate into and out of our line of sight, we perceive a rise and fall in X-ray brightness.

This subgroup of pulsating neutron stars, called pulsars, rotate rapidly, emitting from their magnetic poles powerful beams of light that sweep around as the star spins, much like a lighthouse. At Earth, these beams are seen as flashes of light, blinking on and off at intervals from seconds down to milliseconds.

Because of their predictable pulsations -- especially millisecond pulsars, which are the target of the navigation demonstration -- "they are extremely reliable celestial clocks" and can provide high-precision timing just like the atomic clock signals supplied through the 26-satellite, military-operated Global Positioning System (GPS), an Earth-centric system that weakens the farther one travels out beyond Earth orbit and into the solar system, Arzoumanian said. "Pulsars, on the other hand, are accessible in virtually every conceivable flight regime, from low-Earth orbit to interplanetary to deepest space," Gendreau added.

As a result, NICER/SEXTANT also will demonstrate the viability of pulsar-based navigation. "The hardware needed for neutron star science is identical to that needed for pulsar-based navigation," Gendreau said. "In fact, the mission's two goals share many of the same targets and the same operational concept. The differences are on the back end in terms of how the data will be used."

To demonstrate the navigation technology's viability, the NICER/SEXTANT payload will use its telescopes to detect X-ray photons within these powerful beams of light to estimate the arrival times of the pulses. With these measurements, the system will use specially developed algorithms to stitch together an on-board navigation solution.

If an interplanetary mission were equipped with such a navigational device, it would be able to calculate its location autonomously, independent of NASA's Deep Space Network (DSN), Gendreau said. DSN, considered the most sensitive telecommunications system in the world, allows NASA to continuously observe and communicate with interplanetary spacecraft. However, like GPS, the system is Earth-centric. DSN-supplied navigational solutions also degrade the farther one travels out into the solar system. Furthermore, missions must share time on the network, Gendreau said.

"We're excited about NICER/SEXTANT's possibilities," Gendreau added. "The experiment meets critical science objectives and is a stepping-stone for technology applications that meet a variety of NASA needs. It's rare that you get an opportunity to do a cross-cutting experiment like this."

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Source: http://feeds.sciencedaily.com/~r/sciencedaily/space_time/astronomy/~3/SL-GcAeiWQ8/130408035333.htm

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