Why Working From Home Is a “Future-looking Technology” 01-07

Working from home gets a bad rap. Google the phrase and examine the results — you’ll see scams or low-level jobs, followed by links calling out “legitimate” virtual jobs.

But Stanford Graduate School of Business professor Nicholas Bloom says requiring employees to be in the office is an outdated work tradition, set up during the Industrial Revolution. Such inflexibility ignores today’s sophisticated communications methods and long commutes, and actually hurts firms and employees.

“Working from home is a future-looking technology,” Bloom told an audience during TEDxStanford, which took place in April. “I think it has enormous potential.”

To test his claim, Bloom, with co-researchers James Liang, John Roberts, and Zhichun Jenny Ying, studied China’s largest travel agency, Ctrip. Headquartered in Shanghai, the company has 20,000 employees and a market capitalization of about $20 billion.

The company’s leaders — conscious of how expensive real estate is in Shanghai — were interested in the impact of working from home. Could they continue to grow while avoiding exorbitant office space costs? They solicited worker volunteers for a study in which half worked from home for nine months, coming into the office one day a week, and half worked only from the office.

Bloom tracked these two groups for about two years. The results? “We found massive, massive improvement in performance — a 13% improvement in performance from people working at home,” Bloom says.

Two reasons led to that uptick: First, people working from home actually work their full shift. In the office, people might be delayed by traffic, take a long lunch with a colleague, or leave work early to let a repair person in. They are less likely to be on the clock for the full workday. 

Second, Bloom says, people at home are able to concentrate better. “The office is actually an amazingly noisy environment. There’s a cake in the break room; Bob’s leaving, come join. The World Cup sweepstakes is going. Whatever it is, the office is super-distracting.”

Also, his study found that resignations at the company dropped by 50% when employees were allowed to work from home. “Not only do the employees benefit (by working from home), but the managers benefit because they can spend less of their time painfully advertising, recruiting, training, and promoting.”

Bloom says the experiment led Ctrip to roll out a work-from-home option to all its employees. The company reported that it made about $2,000 more profit per person at home, Bloom says.

Bloom hopes this example helps kill the negative stereotypes of working from home. “For employees, they’re much more productive and happier. For managers, you don’t have to spend so much time recruiting and training people. For firms, you make far more profit. For society, there’s a huge saving of reducing congestion, driving times and, ultimately, pollution.

“There’s not much to lose, and there’s a lot to gain,” he says. 

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Researchers: Should You Be a Specialist? 04-12

Researchers: Should You Be a Specialist?

Stanford scholars explore how the path you take affects your career prospects.

It’s one of the first questions John-Paul Ferguson hears from the first year students in the strategy course he teaches each year at Stanford Graduate School of Business: Is it better to have a career as a specialist, or take the path less traveled and develop a broad skill set from a range of experiences and areas?

Ferguson and his colleague, Sharique Hasan, had their assumptions as to the answer, and it was easy to romanticize one notion over another. But the truth is, “It’s a very hard thing to know,” Ferguson says. “For most folks, we can’t tell.” There are far too many variables.

Then the professors got excited. If they looked at the officers in the Indian Administrative Service (IAS) — the bureaucratic service of the government of India and one of the most prestigious careers in the country — there was a natural data set to study. Here were talented individuals chosen for a coveted sector. And once inside, they moved positions, without their control. That was the key: These more than 4,000 individuals selected for the IAS from 1974-2008 didn’t get to pick how generalized or specialized they were in the career paths to the coveted and highly selective positions within the system.

“The IAS can be thought of a system that sifts through the population to identify individuals with comparable high ability, assigns those individuals careers that vary in the diversity of the constituent experiences, and evaluates those individuals for a common set of rewards,” the authors write in their recent report for Administrative Science Quarterly.

 Ferguson and Hasan not only were interested in the question of specialization versus broad experience, but also they were interested in whether its importance varied at different stages of the officers’ careers. What they found was that specialization helps at all stages.

Early in the officers’ careers, the authors conclude, specialization signals general ability. Specialized officers get promoted more, but not necessarily to do jobs in their specialization. Later, those who have specialized are rewarded for the skills they have acquired. To some extent, specialization produced a self-fulfilling prophecy, “wherein people who specialize acquire skills and thus have incentives to continue specializing.”

Ferguson mentions that, if a person moves around from career to career, “you can’t tell if they’re good at everything or bad at everything. For most people, it makes sense to specialize.” A diverse work history, the study concludes, hurts one’s chances of promotion.

That said, Ferguson also wants to emphasize that one of the benefits of a student’s period in business school is the chance to experiment with different career options. “That’s the time when it doesn’t hurt them,” he says. “This is the chance they have to get a little bit of experience. You want to sample as many different kinds while you’re in business school.

Given these findings, Ferg

uson and Hasan are now interested in taking the next step in their research. Whereas the IAS enabled them to explore a pool of employees changing jobs under one employer, the authors would next like to examine this question of specialization among candidates who change both jobs and employers.

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Scientists pinpoint brain’s area for numeral recognition 10-20

Scientists pinpoint brain’s area for numeral recognition

BY BRUCE GOLDMAN

Steve Fisch 

Jennifer Shum and Josef Parvizi led a team that identified a tiny area in the brain that processes numerals.

Scientists at the Stanford University School of Medicine have determined the precise anatomical coordinates of a brain “hot spot,” measuring only about one-fifth of an inch across, that is preferentially activated when people view the ordinary numerals we learn early on in elementary school, like “6” or “38.”

Activity in this spot relative to neighboring sites drops off substantially when people are presented with numbers that are spelled out (“one” instead of “1”), homophones (“won” instead of “1”) or “false fonts,” in which a numeral or letter has been altered.

“This is the first-ever study to show the existence of a cluster of nerve cells in the human brain that specializes in processing numerals,” said Josef Parvizi, MD, PhD, associate professor of neurology and neurological sciences and director of Stanford’s Human Intracranial Cognitive Electrophysiology Program  . “In this small nerve-cell population, we saw a much bigger response to numerals than to very similar-looking, similar-sounding and similar-meaning symbols.

“It’s a dramatic demonstration of our brain circuitry’s capacity to change in response to education,” he added. “No one is born with the innate ability to recognize numerals.”

The finding pries open the door to further discoveries delineating the flow of math-focused information processing in the brain. It also could have direct clinical ramifications for patients with dyslexia for numbers and with dyscalculia: the inability to process numerical information.

the inferior temporal gyrus, a superficial region of the outer cortex on the brain. The inferior temporal gyrus is already generally known to be involved in the processing of visual information.

The new study, published April 17 in the Journal of Neuroscience, builds on an earlier one in which volunteers had been challenged with math questions. “We had accumulated lots of data from that study about what parts of the brain become active when a person is focusing on arithmetic problems, but we were mostly looking elsewhere and hadn’t paid much attention to this area within the inferior temporal gyrus,” said Parvizi, who is senior author of the study.

Not, that is, until fourth-year medical student Jennifer Shum, who also is doing research in Parvizi’s lab, noticed that, among some subjects in the first study, a spot in the inferior temporal gyrus seemed to be substantially activated by math exercises. Charged with verifying that this observation was consistent from one patient to the next, Shum, the study’s lead author, reported that this was indeed the case. So, Parvizi’s team designed a new study to look into it further.

The new study relied on epileptic volunteers who, as a first step toward possible surgery to relieve unremitting seizures that weren’t responding to therapeutic drugs, had a small section of their skulls removed and electrodes applied directly to the brain’s surface. The procedure, which doesn’t destroy any brain tissue or disrupt the brain’s function, had been undertaken so that the patients could be monitored for several days to help attending neurologists find the exact location of their seizures’ origination points. While these patients are bedridden in the hospital for as much as a week of such monitoring, they are fully conscious, in no pain and, frankly, a bit bored.

Over time, Parvizi identified seven epilepsy patients with electrode coverage in or near the inferior temporal gyrus and got these patients’ consent to undergo about an hour’s worth of tests in which they would be shown images presented for very short intervals on a laptop computer screen, while activity in their brain regions covered by electrodes was recorded. Each electrode picked up activity from an area corresponding to about a half-million nerve cells (a drop in the bucket in comparison to the brain’s roughly 100 billion nerve cells).

To make sure that any numeral-responsive brain areas identified were really responding to numerals — and not just generic lines, angles and curves — these tests were carefully calibrated to distinguish brain responses to visual presentations of the classic numerals taught in Western schools, such as 3 or 50, as opposed to squiggly lines, letters of the alphabet, number-denoting words such as “three” or “fifty,” and symbols that in fact were also numerals but — because they were drawn from the Thai, Tibetan and Devanagari languages — were extremely unlikely to be recognized as such by this particular group of volunteers.

In the first test, subjects were shown series of single numerals and letters — along with false fonts, in which the component parts of numerals or letters had been scrambled but defining curves and angles were retained, and the foreign-number symbols just described. A second test, controlling for meaning and sound, included numerals and their spelled-out versions (for instance, “1” and “one,” or “3” and “three”) and other words with the same sound or a similar one (“won” and “tree,” respectively).

All of our brains are shaped slightly differently. But in almost the identical spot within each study subject’s brain, the investigators observed a significantly larger response to numerals than to similar-shaped stimuli, such as letters or scrambled letters and numerals, or to words that either meant the same as the numerals or sounded like them.

Interestingly, said Parvizi, that numeral-processing nerve-cell cluster is parked within a larger group of neurons that is activated by visual symbols that have lines with angles and curves. “These neuronal populations showed a preference for numerals compared with words that denote or sound like those numerals,” he said. “But in many cases, these sites actually responded strongly to scrambled letters or scrambled numerals. Still, within this larger pool of generic neurons, the ‘visual numeral area’ preferred real numerals to the false fonts and to same-meaning or similar-sounding words.”

It seems, Parvizi said, that “evolution has designed this brain region to detect visual stimuli such as lines intersecting at various angles — the kind of intersections a monkey has to make sense of quickly when swinging from branch to branch in a dense jungle.” The adaptation of one part of this region in service of numeracy is a beautiful intersection of culture and neurobiology, he said.

Having nailed down a specifically numeral-oriented spot in the brain, Parvizi’s lab is looking to use it in tracing the pathways described by the brain’s number-processing circuitry. “Neurons that fire together wire together,” said Shum. “We want to see how this particular area connects with and communicates with other parts of the brain.”

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Method of recording brain activity could lead to 'mind-reading' devices, scientists say 10-19

Method of recording brain activity could lead to 'mind-reading' devices, scientists say

BY BRUCE GOLDMAN

Josef Parvizi

A brain region activated when people are asked to perform mathematical calculations in an experimental setting is similarly activated when they use numbers — or even imprecise quantitative terms, such as “more than”— in everyday conversation, according to a study by Stanford University School of Medicine scientists.

Using a novel method, the researchers collected the first solid evidence that the pattern of brain activity seen in someone performing a mathematical exercise under experimentally controlled conditions is very similar to that observed when the person engages in quantitative thought in the course of daily life. 

“We’re now able to eavesdrop on the brain in real life,” said Josef Parvizi, MD, PhD, associate professor of neurology and neurological sciences and director of Stanford’s Human Intracranial Cognitive Electrophysiology Program  . Parvizi is the senior author of the study, published Oct. 15 in Nature Communications. The study’s lead authors are postdoctoral scholar Mohammad Dastjerdi, MD, PhD, and graduate student Muge Ozker.

The finding could lead to “mind-reading” applications that, for example, would allow a patient who is rendered mute by a stroke to communicate via passive thinking. Conceivably, it could also lead to more dystopian outcomes: chip implants that spy on or even control people’s thoughts.

“This is exciting, and a little scary,” said Henry Greely, JD, the Deane F. and Kate Edelman Johnson Professor of Law and steering committee chair of the Stanford Center for Biomedical Ethics  , who played no role in the study but is familiar with its contents and described himself as “very impressed” by the findings. “It demonstrates, first, that we can see when someone’s dealing with numbers and, second, that we may conceivably someday be able to manipulate the brain to affect how someone deals with numbers.”

The researchers monitored electrical activity in a region of the brain called the intraparietal sulcus, known to be important in attention and eye and hand motion. Previous studies have hinted that some nerve-cell clusters in this area are also involved in numerosity, the mathematical equivalent of literacy. 

However, the techniques that previous studies have used, such as functional magnetic resonance imaging, are limited in their ability to study brain activity in real-life settings and to pinpoint the precise timing of nerve cells’ firing patterns. These studies have focused on testing just one specific function in one specific brain region, and have tried to eliminate or otherwise account for every possible confounding factor. In addition, the experimental subjects would have to lie more or less motionless inside a dark, tubular chamber whose silence would be punctuated by constant, loud, mechanical, banging noises while images flashed on a computer screen.

“This is not real life,” said Parvizi. “You’re not in your room, having a cup of tea and experiencing life’s events spontaneously.” A profoundly important question, he said, is: “How does a population of nerve cells that has been shown experimentally to be important in a particular function work in real life?” 

His team  ’s method, called intracranial recording, provided exquisite anatomical and temporal precision and allowed the scientists to monitor brain activity when people were immersed in real-life situations. Parvizi and his associates tapped into the brains of three volunteers who were being evaluated for possible surgical treatment of their recurring, drug-resistant epileptic seizures.

The procedure involves temporarily removing a portion of a patient’s skull and positioning packets of electrodes against the exposed brain surface. For up to a week, patients remain hooked up to the monitoring apparatus while the electrodes pick up electrical activity within the brain. This monitoring continues uninterrupted for patients’ entire hospital stay, capturing their inevitable repeated seizures and enabling neurologists to determine the exact spot in each patient’s brain where the seizures are originating.

During this whole time, patients remain tethered to the monitoring apparatus and mostly confined to their beds. But otherwise, except for the typical intrusions of a hospital setting, they are comfortable, free of pain and free to eat, drink, think, talk to friends and family in person or on the phone, or watch videos.

The electrodes implanted in patients’ heads are like wiretaps, each eavesdropping on a population of several hundred thousand nerve cells and reporting back to a computer.

In the study, participants’ actions were also monitored by video cameras throughout their stay. This allowed the researchers later to correlate patients’ voluntary activities in a real-life setting with nerve-cell behavior in the monitored brain region. 

As part of the study, volunteers answered true/false questions that popped up on a laptop screen, one after another. Some questions required calculation — for instance, is it true or false that 2+4=5? — while others demanded what scientists call episodic memory — true or false: I had coffee at breakfast this morning. In other instances, patients were simply asked to stare at the crosshairs at the center of an otherwise blank screen to capture the brain’s so-called “resting state.”

Consistent with other studies, Parvizi’s team found that electrical activity in a particular group of nerve cells in the intraparietal sulcus spiked when, and only when, volunteers were performing calculations.

Afterward, Parvizi and his colleagues analyzed each volunteer’s daily electrode record, identified many spikes in intraparietal-sulcus activity that occurred outside experimental settings, and turned to the recorded video footage to see exactly what the volunteer had been doing when such spikes occurred.

They found that when a patient mentioned a number — or even a quantitative reference, such as “some more,” “many” or “bigger than the other one” — there was a spike of electrical activity in the same nerve-cell population of the intraparietal sulcus that was activated when the patient was doing calculations under experimental conditions. 

That was an unexpected finding. “We found that this region is activated not only when reading numbers or thinking about them, but also when patients were referring more obliquely to quantities,” said Parvizi.

“These nerve cells are not firing chaotically,” he said. “They’re very specialized, active only when the subject starts thinking about numbers. When the subject is reminiscing, laughing or talking, they’re not activated.” Thus, it was possible to know, simply by consulting the electronic record of participants’ brain activity, whether they were engaged in quantitative thought during nonexperimental conditions.

Any fears of impending mind control are, at a minimum, premature, said Greely. “Practically speaking, it’s not the simplest thing in the world to go around implanting electrodes in people’s brains. It will not be done tomorrow, or easily, or surreptitiously.”

Parvizi agreed. “We’re still in early days with this,” he said. “If this is a baseball game, we’re not even in the first inning. We just got a ticket to enter the stadium.”

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Incentive plan for Washington teachers drives performance gains, Stanford, Virginia researchers say 10-18

Incentive plan for Washington teachers drives performance gains, Stanford, Virginia researchers say

New study counters earlier research showing performance pay is ineffective, and suggests that under certain conditions incentives influence behavior.

SmileyManWithAHat/Creative Commons

Researchers examined the teacher incentive plan at Washington, D.C., schools.

IMPACT, the controversial teacher-evaluation system recently introduced in the District of Columbia Public Schools (DCPS), appears to have caused hundreds of teachers in the district to improve their performance markedly while also encouraging some low-performing teachers to voluntarily leave the district's classrooms, according to a new study from the Stanford Graduate School of Education   and the University of Virginia Curry School of Education  .

IMPACT is a performance-assessment system linking high-powered incentives and teacher evaluations. It grabbed immediate national attention for its explicit dismissal policy for teachers it rated as ineffective as well as for its substantial financial rewards for high-performing teachers.

Specifically, high-performing teachers as assessed by IMPACT earn an annual bonus of as much as $25,000, as well as an opportunity for similarly large and permanent increases in their base salaries. In contrast, teachers who are unable to achieve an "effective" rating after two years are dismissed.

The findings run counter to a spate of recent studies that found that incentives linked narrowly to test scores were not associated with a change in teacher performance. The study   will be posted this week as a National Bureau of Economic Research (NBER) Working Paper.

"IMPACT provides a unique opportunity to examine the effects of a multi-faceted system of teacher evaluation and supports coupled with non-trivial incentives for teacher performance. We find strong evidence that this system causes meaningful increases in teacher performance," said James Wyckoff  , a professor of education at the University of Virginia Curry School of Education and co-author of the study.

Teacher assessments

"We know that good teachers make a dramatic difference in the lives of their students. However, we also know that there is considerable variation in teacher quality and too many disadvantaged children don't have access to the highly effective teachers they need to realize their potential," added Thomas Dee  , a professor of education at the Stanford Graduate School of Education and co-author of the study.

To try to address that issue, DCPS introduced IMPACT during the tenure of Chancellor Michelle Rhee and first began evaluating teachers during the 2009-10 school year. IMPACT's teacher performance assessments are based on multiple measures of performance, not just students' test results. Teachers, for example, are observed in their classrooms five times throughout the year and rated on nine explicit criteria that the district uses to define effective instruction, including how well they explain concepts and if they check for student understanding. School administrators also rate DCPS teachers on their support of school initiatives, their efforts to promote high expectations and their demonstration of core professionalism.

The aggregation of these measures rates teachers on a scale of 100 to 400. A score of 350 or more means highly effective; 250 or more, effective; under 250, minimally effective; and under 175, ineffective.

Teachers who score above 350 receive a bonus for a given year, and a permanent pay increase if they exceed the bar a second consecutive year. Effective teachers receive their scheduled pay increases while ineffective teachers are immediately dismissed. The "minimally effective" teachers (i.e., scores below 250 but above 174) are told they have one year to become effective or they face the threat of dismissal.

Since the study was completed, the district has made adjustments to the scoring scale.

The results

The study found that in IMPACT's first year a minimally effective rating had no clear effect on either a teacher's retention or their performance. However, following the second year of IMPACT, the authors found that teachers who had one minimally effective rating were much more likely to voluntarily exit and those who remained disproportionately improved. Similarly, teachers eligible for increases in base pay as a result of being rated highly effective twice also showed strong improvement relative to high performing teachers not eligible for the pay increases.

Teachers who had been rated just below 250 and returned for the 2011-12 school year increased their IMPACT scores by roughly 12.6 points more than teachers who had been rated at 250 and just above. That is, these teachers who faced a dismissal threat surpassed most of the teachers whose scores were just above the "effective" threshold and therefore did not face the same incentives. This gain in teacher performance is equivalent to moving a teacher from the 10th to the 15th percentile of the district's performance distribution. This gain is also similar to half of the performance gains observed among the district's novice teachers during their first three years in the classroom.

"Highly effective" teachers, who may have been motivated by the chance of earning a permanent pay increase if they maintained their rating for a second consecutive year, also showed a noticeable jump in their measured performance. According to the findings, they improved, on average, by roughly 10.9 IMPACT points, a gain equivalent to moving a teacher from the 78th to the 85th percentile of the district's performance distribution.

The researchers also found that dismissal threats shaped the district's teaching workforce through the voluntary attrition of low-performing teachers. Approximately 20 percent of the DCPS teachers who received a score just above the effective threshold rating for the 2010-11 school year did not return for the subsequent year. For the minimally effective teachers just below this threshold, the probability of not returning to the district's classrooms jumped to 31 percent, an increase of more than 50 percent.

In contrast, the study found that the base-pay incentives did not clearly increase the retention rates of highly effective teachers who were already retained at much higher rates than low-performing teachers.

"A key part of what makes these results compelling to us is our ability to credibly rule out alternative explanations. Our research design compares outcomes among teachers whose performance in the prior year happened to place them just above or just below the score thresholds that separate IMPACT's rating categories," said Dee. "In short, our study identifies the differences in outcomes between teachers who face sharp differences in performance incentives but who are essentially identical in all other respects. Thus, this research design allows us to isolate the effects of the incentives in IMPACT from the effects of differences in prior performance."

The study notes that the findings do not necessarily speak to those teachers who score away from the thresholds – those who are consistently scored as solidly "effective," for example.

Incentives and support

According to Dee and Wyckoff, these results are almost certainly about more than incentives alone. There have been a number of previous studies of financial incentive programs, including tests of pilot programs in Nashville, New York City and Chicago, and they have not yielded evidence of meaningful change in teacher performance. Some researchers speculate that those programs didn't offer big enough rewards and that they focused too narrowly on test scores rather than the instructional practices teachers can control more directly.

Dee and Wyckoff contend that the IMPACT program is a much better case study to determine whether more sophisticated performance assessments of teachers coupled with incentives are an effective strategy to motivate and retain high-quality teachers. IMPACT spans one of the nation's major urban school districts, features bigger pay incentives and focuses on the differential retention of high-performing teachers rather than only seeking to raise the performance of existing teachers. In addition, IMPACT, which is currently in its fifth year, has proven more durable than most teacher-compensation programs, so DCPS teachers are unlikely to view it as provisional policy.

"For these reasons, we viewed IMPACT as a uniquely powerful test. If the high-powered incentives and supports that IMPACT created didn't work during a sustained application, we would've viewed that as a nail in the coffin of this literature," Dee said.

While the researchers say the results should be encouraging for districts on the fence about implementing incentive programs, they also warn that IMPACT is not one size fits all.

"Perhaps most important are the implementation details that were coupled with these incentives," Wyckoff added. "IMPACT appears to have been comparatively successful in defining what teachers need to do in order to improve their scores and providing corresponding supports. Evaluations and incentives are likely to have little effect if teachers lack the knowledge and support to act on the information the evaluations provide."

"It's not easy for districts to develop and implement a system of this scale and sophistication," said Dee. He noted that the program includes data systems management, communications, careful training of raters on the district's structured rubrics and ongoing support of teacher improvement (for example, instructional coaches).

The researchers cautioned that if school districts push out lower performing teachers, they must also consider whom they hire to replace them. The study found that DCPS was able to recruit new teachers whose performance substantially exceeded the performance of those they replaced.

Funding for the study came from the Carnegie Corporation of New York and the National Center for the Analysis of Longitudinal Data in Education Research, or CALDER.

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Stanford scientists use 'wired microbes' to generate electricity from sewage 09-17

Stanford scientists use 'wired microbes' to generate electricity from sewage

An interdisciplinary team has created a "microbial battery" driven by naturally occurring bacteria that have evolved to produce electricity as they digest organic material.

BY TOM ABATE

Xing Xie, Stanford Engineering

The tubular growth depicted here is a type of microbe that can produce electricity. Its wire-like tendrils are attached to a carbon filament. This image is taken with a scanning electron microscope. More than 100 of these 'exoelectrogenic microbes' could fit side by side in a human hair.

Engineers at Stanford have devised a new way to generate electricity from sewage, using naturally occurring "wired microbes" as mini power plants, producing electricity as they digest plant and animal waste.

In a paper published today   in the Proceedings of the National Academy of Sciences, co-authors Yi Cui  , a materials scientist, Craig Criddle  , an environmental engineer, and Xing Xie, an interdisciplinary researcher, call their invention a microbial battery.

They hope it will be used in places such as sewage treatment plants, or to break down organic pollutants in the "dead zones" of lakes and coastal waters where fertilizer runoff and other organic waste can deplete oxygen levels and suffocate marine life.

At the moment, however, their laboratory prototype is about the size of a D-cell battery and looks like a chemistry experiment, with two electrodes, one positive, the other negative, plunged into a bottle of wastewater.

Inside that murky vial, attached to the negative electrode like barnacles to a ship's hull, an unusual type of bacteria feast on particles of organic waste and produce electricity that is captured by the battery's positive electrode.

"We call it fishing for electrons," said Criddle, a professor in the department of civil and environmental engineering.

Scientists have long known of the existence of what they call exoelectrogenic microbes – organisms that evolved in airless environments and developed the ability to react with oxide minerals rather than breathe oxygen as we do, to convert organic nutrients into biological fuel.

Over the last dozen years or so, several research groups have tried various ways to use these microbes as bio-generators, but tapping this energy efficiently has proven challenging.

What is new about the microbial battery is a simple yet efficient design that puts these exoelectrogenic bacteria to work.

At the battery's negative electrode, colonies of wired microbes cling to carbon filaments that serve as efficient electrical conductors. Using a scanning electron microscope, the Stanford team captured images of these microbes attaching milky tendrils to the carbon filaments.

"You can see that the microbes make nanowires to dump off their excess electrons," Criddle said. To put the images into perspective, about 100 of these microbes could fit, side by side, in the width of a human hair.

As these microbes ingest organic matter and convert it into biological fuel, their excess electrons flow into the carbon filaments, and across to the positive electrode, which is made of silver oxide, a material that attracts electrons.

The electrons flowing to the positive node gradually reduce the silver oxide to silver, storing the spare electrons in the process. According to Xie, after a day or so the positive electrode has absorbed a full load of electrons and has largely been converted into silver.

At that point it is removed from the battery and re-oxidized back to silver oxide, releasing the stored electrons.

The Stanford engineers estimate that the microbial battery can extract about 30 percent of the potential energy locked up in wastewater. That is roughly the same efficiency at which the best commercially available solar cells convert sunlight into electricity.

Of course, there is far less energy potential in wastewater. Even so, the inventors say the microbial battery is worth pursuing because it could offset some of the electricity now used to treat wastewater. That use currently accounts for about 3 percent of the total electrical load in developed nations. 

Most of this electricity goes toward pumping air into wastewater at conventional treatment plants where ordinary bacteria use oxygen in the course of digestion, just like humans and other animals.

Looking ahead, the Stanford engineers say their biggest challenge will be finding a cheap but efficient material for the positive node.

"We demonstrated the principle using silver oxide, but silver is too expensive for use at large scale," said Cui, an associate professor of materials science and engineering.

"Though the search is underway for a more practical material, finding a substitute will take time."

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'Love hormone' may play wider role in social interaction than previously thought, scientists say 09-14

'Love hormone' may play wider role in social interaction than previously thought, scientists say

BY BRUCE GOLDMAN

Robert Malenka and Gul Dolen  found that the hormne known as oxytocin plays a stronger role in social bonding than previously thought.

Researchers at the Stanford University School of Medicine have shown that oxytocin — often referred to as "the love hormone" because of its importance in the formation and maintenance of strong mother-child and sexual attachments — is involved in a broader range of social interactions than previously understood.

The discovery may have implications for neurological disorders such as autism, as well as for scientific conceptions of our evolutionary heritage.   

Scientists estimate that the advent of social living preceded the emergence of pair living by 35 million years. The new study suggests that oxytocin's role in one-on-one bonding probably evolved from an existing, broader affinity for group living.

Oxytocin is the focus of intense scrutiny for its apparent roles in establishing trust between people, and has been administered to children with autism spectrum disorders in clinical trials. The new study, published Sept. 12 in Nature, pinpoints a unique way in which oxytocin alters activity in a part of the brain that is crucial to experiencing the pleasant sensation neuroscientists call "reward." The findings not only provide validity for ongoing trials of oxytocin in autistic patients, but also suggest possible new treatments for neuropsychiatric conditions in which social activity is impaired.

"People with autism-spectrum disorders may not experience the normal reward the rest of us all get from being with our friends," said Robert Malenka, MD, PhD, the study's senior author. "For them, social interactions can be downright painful. So we asked, what in the brain makes you enjoy hanging out with your buddies?"

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Some genetic evidence suggests the awkward social interaction that is a hallmark of autism-spectrum disorders may be at least in part oxytocin-related. Certain variations in the gene that encodes the oxytocin receptor — a cell-surface protein that senses the substance's presence — are associated with increased autism risk.

Malenka, the Nancy Friend Pritzker Professor in Psychiatry and Behavioral Sciences, has spent the better part of two decades studying the reward system — a network of interconnected brain regions responsible for our sensation of pleasure in response to a variety of activities such as finding or eating food when we're hungry, sleeping when we're tired, having sex or acquiring a mate, or, in a pathological twist, taking addictive drugs. The reward system has evolved to reinforce behaviors that promote our survival, he said.

For this study, Malenka and lead author Gül Dölen, MD, PhD, a postdoctoral scholar in his group with over 10 years of autism-research expertise, teamed up to untangle the complicated neurophysiological underpinnings of oxytocin's role in social interactions. They focused on biochemical events taking place in a brain region called the nucleus accumbens, known for its centrality to the reward system.

In the 1970s, biologists learned that in prairie voles, which mate for life, the nucleus accumbens is replete with oxytocin receptors. Disrupting the binding of oxytocin to these receptors impaired prairie voles' monogamous behavior. In many other species that are not monogamous by nature, such as mountain voles and common mice, the nucleus accumbens appeared to lack those receptors.

"From this observation sprang a dogma that pair bonding is a special type of social behavior tied to the presence of oxytocin receptors in the nucleus accumbens. But what's driving the more common group behaviors that all mammals engage in — cooperation, altruism or just playing around — remained mysterious, since these oxytocin receptors were supposedly absent in the nucleus accumbens of most social animals," said Dölen.

The new discovery shows that mice do indeed have oxytocin receptors at a key location in the nucleus accumbens and, importantly, that blocking oxytocin's activity there significantly diminishes these animals' appetite for socializing. Dölen, Malenka and their Stanford colleagues also identified, for the first time, the nerve tract that secretes oxytocin in the region, and they pinpointed the effects of oxytocin release on other nerve tracts projecting to this area.

Mice can squeak, but they can't talk, Malenka noted. "You can't ask a mouse, 'Hey, did hanging out with your buddies a while ago make you happier?'" So, to explore the social-interaction effects of oxytocin activity in the nucleus accumbens, the investigators used a standard measure called the conditioned place preference test.

"It's very simple," Malenka said. "You like to hang out in places where you had fun, and avoid places where you didn't. We give the mice a 'house' made of two rooms separated by a door they can walk through at any time. But first, we let them spend 24 hours in one room with their littermates, followed by 24 hours in the other room all by themselves. On the third day we put the two rooms together to make the house, give them complete freedom to go back and forth through the door and log the amount of time they spend in each room."

Mice normally prefer to spend time in the room that reminds them of the good times they enjoyed in the company of their buddies. But that preference vanished when oxytocin activity in their nucleus accumbens was blocked. Interestingly, only social activity appeared to be affected. There was no difference, for example, in the mice's general propensity to move around. And when the researchers trained the mice to prefer one room over the other by giving them cocaine (which mice love) only when they went into one room, blocking oxytocin activity didn't stop the mice from picking the cocaine den.

In an extensive series of sophisticated, highly technical experiments, Dölen, Malenka and their teammates located the oxytocin receptors in the murine nucleus accumbens. These receptors lie not on nucleus accumbens nerve cells that carry signals forward to numerous other reward-system nodes but, instead, at the tips of nerve cells forming a tract from a brain region called the dorsal Raphe, which projects to the nucleus accumbens. The dorsal Raphe secretes another important substance, serotonin, triggering changes in nucleus accumbens activity. In fact, popular antidepressants such as Prozac, Paxil and Zoloft belong to a class of drugs called serotonin-reuptake inhibitors that increase available amounts of serotonin in brain regions, including the nucleus accumbens.

As the Stanford team found, oxytocin acting at the nucleus accumbens wasn't simply squirted into general circulation, as hormones typically are, but was secreted at this spot by another nerve tract originating in the hypothalamus, a multifunction midbrain structure. Oxytocin released by this tract binds to receptors on the dorsal Raphe projections to the nucleus accumbens, in turn liberating serotonin in this key node of the brain's reward circuitry. The serotonin causes changes in the activity of yet other nerve tracts terminating at the nucleus accumbens, ultimately resulting in altered nucleus accumbens activity — and a happy feeling.

"There are at least 14 different subtypes of serotonin receptor," said Dölen. "We've identified one in particular as being important for social reward. Drugs that selectively act on this receptor aren't clinically available yet, but our study may encourage researchers to start looking at drugs that target it for the treatment of diseases such as autism, where social interactions are impaired."

Malenka and Dölen said they think their findings in mice are highly likely to generalize to humans because the brain's reward circuitry has been so carefully conserved over the course of hundreds of millions of years of evolution. This extensive cross-species similarity probably stems from pleasure's absolutely essential role in reinforcing behavior likely to boost an individual's chance of survival and procreation.

The study was funded by the Simons Foundation Autism Research Initiative   and the Walter and Idun Berry Foundation. Additional Stanford co-authors were technician Ayeh Darvishzadeh and former undergraduate Kee Wui Huang, now a neuroscience graduate student at Harvard University.

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