corporate funding is provided by mutual of america-- designing customized individual and group retirement products. that's why we are your retirement company. additional support is provided by: and by the corporation for public broadcasting and by contributions to your pbs station from viewers like you. thank you. from the tisch wnet studios in lincoln center in new york, hari sreenivasan. >> sreenivasan: good evening. thanks for joining us. in a major reversal, white house officials said today president obama will delay any executive action to reshape the nation's immigration system until after this november's mid-term elections. the president had pledged to act by the end of the summer. white house officials are now saying he will do so before the end of the year. the decision to delay the process is seen as an effort to help democrats in difficult reelection races. nearly 20% of women in the united states have been raped and nearly 44% have been the victims of some sort of sexual violence. this, according to a new report released yesterday by the centers for disease control, the c.d.c. the findings were based on a survey of 12,000 people conducted on both cell phones and landlines. the vast majority of the violence is reportedly perpetrated by past partners or acquaintances. a senate subcommittee, led by michigan democrat carl levin, has concluded that the i.r.s. inappropriately targeted tax- exempt groups but said it found no evidence of political bias. the committee said liberal groups experienced "the same mistreatment" as tea party groups. a dissenting report by republicans said 83% of the targeted groups were conservative-leaning. hundreds of thousands of people throughout parts of the upper midwest are still without power following severe storms yesterday and overnight. in the chicago area, 70-mile-an- hour winds ripped roofs off buildings, brought down trees and blew over a semi on a highway overpass. about 100,000 customers lost power there. another 400,000 michigan residents lost power after the storm moved there. at least one person was killed. turning overseas, life appeared to be returning to normal today in much of eastern ukraine following yesterday's announcement of a cease-fire. ukrainian government troops had battled pro-russian separatists in the area near russia for several months. recently, nato said russian forces crossed the border into ukraine and pushed back ukrainian government forces. russian president vladimir putin conferred by phone today with ukrainian president petro poroshenko. poroshenko said later the two discussed ways to make the cease-fire more stable. the two sides are also exchanging prisoners. in west africa, officials in sierra leone say they will impose a three-day nationwide lockdown later this month to try and stop the spread of the ebola virus. people in the nation of six million will not be allowed to leave their homes. health workers hope the move will help them to identify and isolate new ebola virus cases. more than 2,100 people in four west african countries have died during this ebola outbreak. and syrian government warplanes today attacked islamic state fighters in the north of that country near turkey. at least 25 people reportedly were killed, many of them civilians who died when a missile hit a bakery crowded with shoppers. yesterday, president obama spoke about the need to bolster iraqi military forces to fight the islamic state. >> we can support them from the air, but ultimately we're going to need a strong ground game. >> sreenivasan: for more about efforts to defeat the islamic state, we are joined now from washington by anthony cordesman. he is with the center for strategic and international studies and was the director of intelligence assessment in the office of the secretary of defense. mr. cordesman, the president of the united states has said that we need a ground game, a response, a partial response from the region might be you and what army? who are the people who would actually be on the ground, and help tackle isis. >> the iraqi forces are relatively large, compared to any estimate of what the islamic state's forces are. if you provide the capability and training to make those iraqi forces more effective, if you give the kurdish peshmerga better arms, you really have a force on the ground that is significantly superior to what the islamic state has. if you throw into that u.s. airpower, and that of some other countries, applied not only in iraq but in syria, you have a decisive amount of firepower. and if you add to this the ability to seal off the islamic state on the borders of the areas it occupies, to cut off its economic structure and reduce its flow of volunteers, in combination, that's a lot of leverage. it's also a lot of "ifs." but the problem is not so much the ground game. the problem is to create a structure in iraq where the sunnis and kurds can cooperate with the shiite forces, where you can rebuild the iraqi forces without having them take sides in an ethnic or sectarian civil war. >> sreenivasan: are we confident that the iraqi security forces can be trained up and not walk off the bottle field like they have in previous occasions? >> well, we have to be careful. they didn't exactly walk off the battlefield. they fled. part of it was their leadership is leadership maliki chose on the basis of loyalty by sect and used in ways which abused the local population. are we confident we can change that? no, we're not. nobody can be. this is up to the iraqis and the iraqi government. but so far, there's been enough progress to at least offer hope. and we have seen cooperation between the kurdish forces and the shiite forces, as well as the iraqi forces. we have seen u.s. advisers help the iraqi forces at least try to take back territory in areas like tikrit. so there are some positive signs. there are certainly no guarantees. >> sreenivasan: is there any amount of religious pressure that the leadership in the region can bring to bear on isis? well, that's a critical question. the answer is not pressure, but the problem is we in the west, whether it's in the the united states or its european allies, can never make an argument that we're either an islamic state or that we're arabs. saudi arabia, the united arab emirates, jordan, turkey, can make an argument, and it can join in this. so one of the key issues is to have the clerics in the states that are around the islamic state, to have them make the case as to just how extreme the islamic state is, how much it has departed from the real values of islam. the ideological dimension here is as critical as the military or the political or the economic dimension. >> sreenivasan: would any of those countries in the neighborhoods send in ground troops? >> i think the answer is it would be very difficult. it's not clear what would happen if you sent in saudi or jordanian forces. and certainly, turkish forces would not be an element that would really contribute to stability. the problem in iraq, essentially, is you need to have iraqis on the ground. they don't have to be sunni, but they to be part of a government that sunnis can trust, and the same is true of the kurds. and when it comes down to syria, the fact is, walking in to that particular mess, we're not simply talking about the islamic state or elinous ra, the so-called moderate rebels of which you have more than 70 fragmented elements is not something that can easily be done from the outside. it's even more difficult for the united states to send in ground troops. >> sreenivasan: all right, arthony cordesman joining us from washington, thanks so much. >> thank you. >> sreenivasan: we wanted to follow up tonight on yesterday's unemployment report. the government reported that 142,000 jobs were created last month, well below most expectations. even so, the unemployment rate dropped from 6.2% to 6.1%, in large part because what's known as the participation rate fell. in other words, even more americans dropped out of the workforce. for more about all this, we are joined from washington by sudeep reddy, economics editor at the "wall street journal." so, one of the articles in the "journal "said 60,000 people dropped out of the labor force last month. put that in perspective for us. >> that's right. we've seen over the course of the recovery millions of people just giving up hope, dropping out. the vast majority of people appear to be dropping out, just because they can't finded if jobs and it's not worth staying in. so to see that many people pull out, right now, the labor force participation rate is around 63%. that means there are millions of people who were in the the labor force before, before the recession started in 2007, who aren't coming back in, even when we see improvement in the overall economy, improvement in the labor market. >> sreenivasan: so what are some of the long-term consequences of this low participation rate? >> for the individuals, they're really quite tragic. it means if you're not in the labor force, in a job that suits your skills, that means you're going to spend decades down the line probably earning less than you would have earned otherwise because you start out at a lower base. you're not getting the kind of increases that you would expect in pay and in job quality. that can stunt you and there's research that shows that it can stunt your children as well. that's why it's a big risk that way. it hurt the overall economy in a much broader way. an economy relies on people working at their full potential. it relies on people being-- particularly educated people, being involved in the labor force, looking for good opportunities, looking for good jobs. and you see it in plenty of economies around the world, when you don't have people working at their full potential, it's a deathidation of the economy that reduces the potential to grow and the potential for job creation, for entrepreneurship, for all the things that you would expect to see in a vibrant, thriving economy. >> sreenivasan: all right. and about those who are working, are their wages rising? are they turning around and spending more? >> unfortunately, their wages are not rising very much. we're seeing a very two-track economy right now. on one hand, you see the wealthiest americans-- and there have been some reports this week with new data showing the people who have been make, the most gains, the top 1% to 3%, they're doing quite well, partly because the stock market has been going up so strongly over the last couple of years. everyone else, the other 97% of americans, are generally seeing stagnant wages. that is why you're not seeing consumer spending take off. you see an economy that on the surface looks like it's improving based on all the numbers, but the way everyone's reacting to it, it really isn't gaining that much traction. >> sreenivasan: all right, sudeep reddy of the "wall street journal," thanks so much. >> thank you. >> sreenivasan: and now to our signature story, our original in-depth reports from around the nation and around the world. our focus tonight: the extraordinary sensory power of animals to detect things earlier than we sometimes can. dogs can be trained to help diabetics by detecting when blood sugar levels are too low or too high, and alerting their owners. now, scientists are looking into their abilities to tell us when we have cancer. newshour special correspondent dr. emily senay reports. >> reporter: you've seen them on the streets helping the blind, at airports and train stations sniffing for explosives and at the scene of earthquakes searching for survivors. but ever since her family got a doberman puppy, this 55-year-old retired magazine editor from new york's staten island believes there may be another way for dogs to save lives. one night in the spring of 2011, a couple of weeks after getting a new puppy, diane papazian noticed her dog, troy, behaving strangely. >> he's in bed with us, and he is in between my husband and myself, and... so, his head is right here. and he is nuzzling up against my left side, and he keeps nuzzling, and he's nuzzling, and he's not stopping. and i'm thinking, what in the heck is going on with this dog? cut it out, you know, that's so annoying. what are you doing? and he kept doing it persistently, like it wasn't just once or twice; it was for a few minutes that he kept nuzzling. so, finally i said, "what in the heck is he doing?" so, i started to itch, because i'm highly allergic, and that's when i felt the lump. >> reporter: just days after discovering the lump, doctors found a tumor three centimeters long. diane was diagnosed with an aggressive form of stage two breast cancer. she'd gone for a mammogram six months earlier which was clear, and wasn't due for another mammogram until another six months. when you went to the doctor, did you say, "you know, my dog sort of alerted me to this?" >> yes. >> reporter: what did they say when... when they heard you... heard your story? >> well, i don't think... i think they kind of partly thought i was a little crazy. but i think that they probably have heard enough stories about dogs and their very keen sense of smell that they weren't completely surprised. >> reporter: diane's story might not be so crazy after all. for the past 25 years, cancer researchers have been exploring the possibility that cancer actually smells like something, and that dogs can detect that smell. the idea of dogs smelling cancer makes perfect sense to dr. cindy otto, a veterinarian with a doctorate in veterinary physiology. otto started the penn vet working dog center at the university of pennsylvania in 2007. she thinks dogs could be picking up on the changes in odor researchers believe are created by cancer cells. >> it makes sense that they could change the odors that are released from that person. and a dog, with their extremely sensitive sense of smell, might be able to pick up that change. >> reporter: at the penn vet center, researchers are testing that idea. a team of four dogs like tsunami, a german shepherd, and foster, a labrador retriever, are being trained to detect blood samples from ovarian cancer patients. ovarian cancer kills more than 14,000 women in the u.s. each year and is especially hard to detect in early stages. the dogs are rewarded for sitting down after identifying which of the samples contains cancer. researchers like otto started investigating the idea of dogs smelling cancer after hearing stories from people like diane papazian. >> people would report that their dog was acting differently. and they went to their doctor and they found out they had cancer. or the very first case was a dog that was biting at a mole, and that person went in and found out that it was melanoma. and so, just taking that, the stories that people have, and realizing there's some really important information in those stories. >> reporter: otto acknowledges the research is preliminary-- her study is still ongoing and hasn't been submitted for peer review-- but she says the early results have been exceptional. when you say exceptional, what does that mean? how accurate are they? >> about 90% of the time, these two dogs are telling us, "that's the cancer sample." and the other samples that are out there, whether it's from a normal patient or from a patient with benign ovarian disease, they're like, "nah, it's not that." >> reporter: it's not just the university of pennsylvania. at a meeting of the american urological association in may, a group of italian scientists from milan presented the results of a study claiming a 98% accuracy rate with two dogs in detecting prostate cancer from urine samples. that study has yet to go through scientific review for publication, but researchers are hopeful it will eventually lead to an earlier and more accurate screening tool for prostate cancer. >> the holy grail of oncology has been to try to develop a test, either in the blood or the urine or some bodily fluid, that would allow us to detect cancer at an early stage. >> reporter: dr. gary schwartz is the head of oncology and hematology at columbia university medical center. he's impressed by the results from the italian study but has some doubts about the 98% detection rate. >> i am a little skeptical on the outcome reported in this particular abstract from the milan group. now, maybe prove i'm wrong. i mean, that's the scientific part of me. i'm... but being a scientist as well as a physician, i think we always have to question until we see all the data, and all the information. we shouldn't make any definitive conclusions about any finding. and at this point and in my analysis of the information we have, it's still an open question how good the dog really is. >> reporter: even if the dogs can be trained to detect cancer, how useful will that turn out to be? do you see the day when dogs are used in a practical way to screen for cancer? >> i would say not. i really can't envision a dog si... sitting in a clinical laboratory at a desk or in front of a series of urine samples saying... sniffing around, saying, "oh, this one is and this one isn't." i just... the dog gets distracted on that sample, and it's called maybe negative when it could be positive. so i think we're better than that. i think we have better technology that we can use now to find whether a patient has a cancer. >> reporter: schwartz says there are more promising prospects for early detection, such as tests that find cancer d.n.a. in the blood, but he acknowledges there may be something to the science of using dogs to detect cancer. >> i suspect there is an odor, and that's what the dogs are reacting to. dogs have increased sensitivity. so the dogs are... are showing us something. they're leading us down the path in which we can apply our own scientific methodology to identify what's in the urine to which they are finding offensive, and to which they're reacting to. and this in itself could be a significant advance. >> reporter: we spoke with the head of hematology-oncology at columbia, and he said, "gosh, i don't see the day when dogs are going to be sniffing samples, detecting cancer." >> i think that it's good to have skepticism. i think what we're learning is that not all dogs can do this. it takes special training. but i also agree completely that dogs are not going to be in the hospital laboratories, sniffing samples. our goal with the dogs is to help direct where... how we can build a better screening tool. >> reporter: dr. otto acknowledges that training cancer detecting dogs is time consuming and expensive at more than $30,000 a dog each year, and dogs can only identify a limited number of samples each day. but she sees her research eventually leading to a more efficient screening tool. >> the dogs themselves probably aren't going to do the final job. they're helping us design the tool that will then become the screening tool. something that is more automated, something that is inexpensive and can screen thousands of women, millions of women a year. >> reporter: that's where dr. charlie johnson comes in. he's a physicist at the university of pennsylvania using nanotechnology to develop what amounts to an electronic nose capable of smelling cancer. so one day his device might be programmed to measure the gases and compounds emitted from tumors that dr. otto's dogs are smelling. >> our idea is to create a little device that can actually smell the vapors in the air and use it to smell the vapors that are emitted by blood samples and to tell which people have cancer based on that information. >> reporter: can your robotic nose beat a dog's nose yet? >> the best we can hope for, i think, will be to equal the dog's nose. the dog are amazing. i mean, i think one thing we have done is, we have demonstrated our ability to detect a very small amount of a chemical that people cannot smell at all. >> reporter: johnson hopes to create a cancer detecting device as small as an iphone that could be in every doctor's office, but says they're years away from that goal. but the dog study gives them hope that getting sniffed for cancer by an electronic sensor one day could become a routine procedure. after a double mastectomy and chemotherapy, diane papazian is cancer free today, and she says that's all thanks to troy. >> i always say that had it not been for troy, i don't know if i would be here today. >> reporter: you believe that? >> i know that he was trying to tell me something in his own little, sweet way. >> this is pbs newshour weekend, saturday. >> sreenivasan: this tuesday, "frontline" travels to africa and investigates the worst ebola outbreak on record, the devastating impact it's having on families and health care workers as they wait for the international community to respond more forcefully. here's an excerpt filmed in sierra leone. >> local nurses are on the street warning the outbreak is worsening. even in the doctor without borders hospital, ebola is killing 70% of those it infects. because so few people who go to the hospital ever return, victims are hiding in their homes and infecting their families. the only way to contain ebola is to isolate the infected. this man works with one of sierra leone's disease surveillance teams. it's their job to find victims and get them to the doctors without borders hospital. but they can't keep up with the number of cases. >> two weeks ago, he went through a terrifying ordeal when he was gawrn teened with suspected ebola. it turned out to be a false alarm, and he returned to work. now, he's about to head to another contaminated village. >> i'm putting more people at risk. to transmit the disease to a lot of people, and many people will die. >> sreenivasan: some more news before we leave you tonight. the national institutes of health says the investigation has led to the discovery of improperly stored samples of ricen and pat pathogens in its laboratory that can cause botulism and the plagues. somalia's islamic extremist group al-shabaab confirms its leader was killed monday. and a recently released french hostage from syria says the frenchman accused of killing four people at the brussels jewish museum last may, had beaten and tortured him and other hostages in syria before returning to europe. join us on air and online tomorrow. we'll profile a school in west virginia that has taught year-round for the past 20 years. seve captioning sponsored by wnet captioned by media access group at wgbh access.wgbh.org >> pbs newshour weekend is made possible by: corporate funding is provided by mutual of america-- designing customized individual and group retirement products. that's why we are your retirement company. additional support is provided by: and by the corporation for public broadcasting and by contributions to your pbs henry louis gates, jr.: i've spent much of my life searching for the stories of the african american people. man: our first notation of anthony johnson essentially defines him as "antonio the negro." gates: i've always wanted to tell their history: 5 centuries in the making.