Cataract ups depression risk
Older adults with cataracts are more likely to have symptoms of depression, reports a study in the December issue of Optometry and Vision Science , the official journal of the American Academy of Optometry. The link between cataracts and depression is independent of other factors, and appears strongest among older adults with lower education, according to new research by Haifang Wang, MSc, of Soochow University, Suzhou, China, and colleagues. They write, “[O]ur study sheds further light on the complex relationship between aging, vision loss, cataract, and depression and suggests that there may be a role for cataract surgery in improving mental health in the elderly.”
As part of a community survey study, approximately 4,600 older adults (60 years or older) in one Chinese town completed a ‘depression questionnaire’. Excluding those with previous cataract surgery, nearly half (49 per cent) of older adults in the study had cataracts in at least one eye. On the ‘depression questionnaire’, 8 per cent of subjects had depressive symptoms. Symptoms of depression were more common in women than men (11 per cent versus 5 per cent), and more common in older age groups. Age-related cataracts are the leading cause of visual impairment worldwide and are expected to increase as population demographics shift towards advancing age.
Is that you?
What are the characteristics of the way you say “hello” (or anything else for that matter) that makes you recognisable over the phone? Despite the increasing amount of literature on personal voice quality, very little is actually known about how to characterise the sound of an individual speaker.
Two researchers from UCLA in Los Angeles, California, Dr. Patricia Keating and Dr. Jody Kreiman, are joining forces (as they have done many times in the past) to apply acoustics tools to their linguistics research, investigating this question. Essentially, Dr. Keating and Dr. Kreimen want to find out how to measure what people sound like. “There’s no way to quantify what that means,” Dr. Kreiman said. “When you change something physical, can you predict what that will sound like?”
An individual person’s voice may vary over time because of their emotional state, health, the context of the conversation, or a host of other factors that make quantifying this measurement particularly difficult.
The researchers digitally analysed recordings from 50 women, all native speakers of English, who read five sentences twice on three different days. This analysis looked at multiple acoustic parameters for the vowel and consonant sounds making up the read sentences, such as fundamental frequency, intensities of harmonic frequencies relative to one another, and how they compare to the underlying noise levels within the voice.
These sentences provided each characteristic with a quantitative average and range, the collection of which formed a potential identifying voice profile of sorts. By comparing all of the speakers to this set of characteristics — a particular person’s voice profile — using a random set of their sample sentences, it could be tested for accuracy in distinguishing the correct speaker and compared to how well other sets of characteristics act to distinguish a particular voice.
Looking ahead, answering these questions may help in generating predictions about confusability in the context of both human listeners, who tend to be able to discern recognisably in a matter of seconds, and computer algorithms, that typically require samples closer to a minute in length.
Germ cell tumour breakthrough
Researchers led by scientists at Dana-Farber Cancer Institute, Boston, Massachusetts, U.S., say they have identified unique genomic changes that may be integral to testicular cancer development and explain why the great majority are highly curable with chemotherapy — unlike most solid tumours.
The findings may shed light on factors in other cancers that influence their sensitivity to chemotherapy, according to a report in Nature . Cancers of the testes are known as germ cell tumours (germ cells produce sperm and eggs). In 2016, about 8,720 new cases are expected in the U.S., with about 380 deaths. Although they are rare, primary testicular germ cell tumours are the most common solid cancers in young men.
Most of the tumours are highly sensitive to chemotherapy, and more than 80 per cent of patients with germ cell tumours are cured, even when the cancer has metastasised. However, a significant number become chemotherapy-resistant, and about 10 per cent of patients with metastatic germ cell tumours die as a result.
The new research was carried out by scientists led by Dr. Eliezer Van Allen, MD, of Dana-Farber and the Broad Institute of MIT and Harvard, and Dr. Christopher Sweeney, MBBS, of Dana-Farber. In a comprehensive search for the critical genomic and molecular features of these cancers, the scientists analysed samples of 59 tumours from 49 patients treated between 1997 and 2014 at Dana-Farber/Brigham and Women’s Cancer Center (DF/BWCC) over a period.
Because of their rarity, germ cell tumours haven’t been as intensively studied as other forms of cancer, and research funding is more scarce, Dr. Sweeney said. The new study, Dr. Van Allen said, “gives us insights into germ cell tumour biology that haven’t been found to this degree and provide a strong base to explore these very interesting findings further.”
A dense network
It’s a familiar request in the digital age: one of your friends on social media has a friend who wants to be your friend. Frequent linking among friends of friends can cause a rapid increase in social network connectivity.
A new theoretical model shows that networks evolve very differently depending on how often these “second neighbour” connections occur. The work could offer a better understanding of how dense networks form.
By including friend-of-friend interactions in their model, Dr. Renaud Lambiotte (University of Namur, Belgium), Dr. Paul Krapivsky (Boston University), and Dr. Uttam Bhat and Dr. Sid Redner (both Santa Fe Institute) could control the link density of the network.
“It’s an incredibly simple model that can produce both sparse and dense networks,” says Dr. Redner, a Santa Fe Institute professor.
In their recent paper published in Physical Review Letters , the researchers constructed a general network evolution in which every new node links to one target node already in the network, as well as to each of the neighbours of the target (that is, friends of friends), with copying probability p. The likelihood of each of these “copying” steps turns out to be the crucial factor in how the network evolves.
“It’s kind of exotic, but cool, that such a generic model has all these transitions in it,” Dr. Redner says.
If similar transitions are identified as real networks evolve — like those in social media — the model’s copying mechanism could be an allegory for many real friend-of-friend interactions. The model may also offer a way to study the role of triangles and other so-called “cliques” as information or diseases spread in a population.
