Electronics Using Light Instead of Electricity
Engineers at Penn have theorized a means of shrinking electronics so they could run using light instead of electricity. In the search to create faster, smaller and more energy-efficient electronics, researchers have looked elsewhere in the electromagnetic spectrum.
In the August 26 issue of Physical Review Letters, the Penn theorists outlined how familiar circuit elements–inductors, capacitors and resistors–could be created on the nanoscale (about a billionth of a meter) in order to operate using infrared or visible light. The Penn researchers describe how nanoscale particles of certain materials, depending on their unique optical properties, could work as circuit elements. For example, nanoscale particles of certain metals, such as gold or silver, could perform the same function in manipulating an “electric” current as an inductor does on a circuit board.
Optical electronics would make it possible to create faster computer processors, construct nanoscale antennas or build more information-dense data-storage devices.
Before they could describe how to create optical circuit elements, Dr. Nader Engheta, the H. Nedwill Ramsey Professor of Electrical and Systems Engineering and the lead author, along with his coauthors and students, had to first envision how nanoscale materials might interact with light. To do so they looked at a property critical to basic wave interaction called permittivity, which describes how a particular substance affects electromagnetic fields. If a small sphere is created, about a few tens of nanometers across, they explained, light would affect it differently based on its permittivity.
According to their models, the theorists demonstrated that a nano-sized sphere made up of a nonmetallic material such as glass with permittivity greater than zero would act like a miniaturized capacitor. A nano-sized sphere made up of a metallic material with a permittivity less than zero would act like a miniaturized inductor. Either material could also function like a miniaturized resistor, depending on how the optical energy is lost in it.
“This technology could have innumerable applications for consumer products, advanced instrumentation and even medicine,” Dr. Engheta said.
Using MRI for Early Diagnosis of Schizophrenia
Researchers may have discovered a new way that may assist in the early diagnosis of schizophrenia–by utilizing MRI to study the patient’s brain. Researchers at UPHS looked for subtle brain abnormalities that cannot be seen by the human eye. A study examined the entire brain, looking at distributed patterns of abnormalities rather than differences in specific regions of the brain.
“In this study, we used high-dimensional shape transformations in which we compared a brain image with a template of a normal brain. Through this comparison, we then determined where and how the patient’s brain differed from healthy controls,” explained Dr. Christos Davatzikos, director of the Section of Biomedical Image Analysis in the department of radiology at Penn. “These methods are able to identify abnormalities that could not be detected by human inspection of the images created via MRI and, up until now, structural MRI has typically been used to diagnose physical anomalies like stroke or tumors, but it has not been helpful for diagnosis of psychiatric diseases.”
The results of the study demonstrate that sophisticated computational analysis methods can find unique structural brain characteristics in schizophrenia patients, with a predictive accuracy of more than 83%. Recently, Dr. Davatzikos and his group announced that further analysis of this data with even more sophisticated classification methods achieved a 91% predictive accuracy for diagnosis of schizophrenia via MRI (MICCAI 2005 meeting, Palm Springs, CA).
Dr. Davatzikos further explains, “If you can diagnose schizophrenia early, utilizing MRI along with other tools like genetic disposition, behavioral profiles and functional imaging–before a patient actually develops the disease–we can try to delay the onset of the disease and hopefully have a better outcome for the rest of their life.”
The results of this study are in the November 2005 issue of the JAMA–Archives of General Psychiatry available at http://archpsyc.ama-assn.org/.
Physically Abused Boys Become Abusers as Adults
According to a study in the October 18 issue of the Annals of Internal Medicine, a history of childhood physical abuse may be common in men from urban settings, and these men with physical abuse histories may be more likely to commit domestic violence. The study found that the childhood abuse was primarily committed by parents, with mothers being the most frequent abusers.
“The results provide a circumstantial case that abused boys may ‘learn’ that violence is an acceptable method of conflict resolution in the home,” said Dr. William C. Holmes, assistant professor of medicine & epidemiology and lead author of the study.
The study was conducted among a sample of 197 men aged 18 to 49, living in Philadelphia zip code areas with high incidence of domestic violence against women and girls. Utilizing a scale that is also used to identify domestic violence among girls and women, the researchers found that 51% of the men experienced at least one form of abuse that met the definition of childhood physical abuse. The mean age at the start of abuse was approximately eight years old; the mean age at the end of abuse was approximately 14 years old. Examples of abuse include being hit with an object or being kicked, bit, choked, burned, scalded, or punched.
The study also found that approximately 75% of the identified abuse was carried out by parents, a large amount by the mothers. (The relative amount of time that boys spent with mothers versus fathers–a possible explanation for the difference–was not examined in the study.) Others responsible for abuse included extended family members as well as non-family members.
“The findings point to a number of actions that can be taken,” said Dr. Holmes. “For example, screening for domestic violence and protecting those who screen positive should be as important in boys as it is in girls and women. Reducing the abuse of boys, as well as developing post-abuse interventions for boys who have been abused, will generate direct benefits for the boys and may help their future intimate partners and children.”