“Rediscovery” of a decades-old physics idea reignites the fields of cellular and molecular biology
Review written by Xinyang (David) Bing (LSI)
Lava lamps are fluorescent mixtures of oil and water that are immiscible and, when heated, float around, generating hypnotizing patterns that lull you to sleep. Now, biologists are seriously considering the possibility that the same physics that govern lava lamps may also control almost everything that goes on inside our cells.1 Walk through the halls of MIT and Harvard, Oxford and Cambridge, or of course Princeton, and you would likely hear what everybody is talking about: liquid-liquid phase separation.
Review written by Jaydeep Singh (MAT)
Forecasting the trajectory of tropical cyclones (TC), which are known as hurricanes when they appear in the Atlantic, remains an urgent meteorological challenge. The difficulties in TC prediction were laid bare during 2019’s Hurricane Dorian, a devastating Category 5 storm that swept through the Bahamas and the Southeastern United States. Like many Atlantic storms before it, Dorian underwent the process of rapid intensification (RI), catching scientists off guard with consecutive daily wind strength increases of over 30mph. The effect? Dorian transformed from a Category 2 to Category 5 storm in only two days. The staggering intensification of Atlantic storms raises the following question: what is the science behind these RI events, and how predictable are they?
Review written by Rohini Majumdar (PSY)
Research on life trajectories is one of social science’s most popular exports to policy making. Predictive models for specific life outcomes have been applied to a number of settings, including criminal justice and child-protective services. Despite the real-world relevance and far-reaching impact of this research, not many high-quality datasets exist to support it. The Fragile Families and Child Wellbeing Study (FFCWS), however, is one such enterprise by Princeton’s Center for Research on Child Wellbeing and the Columbia Population Research Center. Over 900 studies have used the FFCWS’s rich longitudinal data, which follows the families of almost 5000 babies born in major US cities around the turn of the millennium. Most of these children were born to unmarried parents, putting these families at a greater risk of splitting up and living in poverty compared to traditional families. Although life trajectory research has been used to inform policy, whether it can also be used to accurately predict specific life outcomes for individuals remains undetermined. To find out, Princeton Sociology’s Matthew Salganik, Ian Lundberg, Alex Kindel, and Sara McLanahan spearheaded the Fragile Families Challenge (FFC), a mammoth scientific mass collaboration based on a research design called the common task method.
Review written by Shanka Subhra Mondal (ELE)
In recent years, machine learning (ML) has become commonplace in our software and devices. Its applications are varied, ranging from finance and marketing to healthcare and computer vision. ML already has the ability to out-perform humans on many tasks, such as video game competitions and image/object recognition, to name a few. At a high-level, ML comprises a set of algorithms that rely heavily on data (training data) to make decisions about another set of data (testing data) that it has not previously encountered. One of the sub-fields of computer vision where machine learning has proven particularly useful is in image classification, where the goal is to categorize objects in a given image. While this task might sound easy for humans, it can be challenging for an algorithm, particularly when the picture is blurred, not properly illuminated, or noisy. Robust image classification is not an easy task.
Review written by Jess Breda (PNI)
Have you ever wondered how information is transferred from one brain to another? This process can occur in a variety of ways, from verbal storytelling to simple hand gestures, and across different backgrounds, such as a flight attendant instructing a first time flyer, or a casual conversation with a friend. We gain information from others on a daily basis. However, to study this on a biological level requires the complicated task of recording from two brains experiencing the same stimuli and aligning their activity in time.
Review written by Renee Waters (PSY)
Humans tend to make individual choices based on a series of past experiences, decisions, and outcomes. Just think about the last time you had some terrible take out: you might decide not to eat at that particular restaurant again based on your previous experience. Maybe, you take the same route to work every day because, in the past, there is less traffic on this particular route. The effects that past experiences have on choices are often termed sequential biases. These biases are present everywhere, especially in value-based decision making. You might wonder, what are the neural mechanisms driving this phenomenon? Christine Constantinople, a former postdoc at Princeton University and now an assistant professor at NYU, began to explore this question along with colleagues in the Brody Lab at Princeton.
Review written by Thiago T. Varella (PSY GS) and Gabriel T. Vercelli (PHY ‘20)
Ever since the spread of SARS-Cov-2 imposed quarantines of global reach, people around the world have voiced their frustrations about social isolation. Indeed, Aristotle said back in 4th century BC, “man is by nature a social animal,” highlighting that our unease towards isolation is at least as ancient as the Classical era. However, as seemingly unnatural as social isolation might be for humans, it plays a crucial role in the current attempts to stave off the pandemic. Interestingly, isolation might serve a similar purpose in the natural world! Individuals that do not engage in collective behaviors have been observed in many social species. This behavioral divergence is usually thought of as an error, a failure to perfectly coordinate all individuals in a population; but this isolation could, at least theoretically be premeditated or shaped by natural selection (Barta, 2016). This leads to the question: are these isolated individuals, also called “loners,” a mere consequence of failed synchronization of the group, or could they be a mechanism nature developed to mitigate the risks of collective action?
Review written by Eleni Papadoyannis (PNI)
How do humans control a complex system like the brain? Over the years, neuroscientists have discovered numerous methods to do exactly that. Applying chemicals, such as muscimol, can drive inhibition to shut down a brain region. Alternatively, shining light can selectively activate certain cell types through the photo-sensitive protein channelrhodopsin. Sending electrical impulses via electrodes in deep brain stimulation (DBS) can also control regional activity in humans. Causal manipulation of the brain not only offers incredible insight into hypotheses relating neural activity to behavior, but also serves as a clinical tool. Electrical and magnetic stimulation methods have been used as therapies for treating patients with a variety of diseases and disorders, such as using DBS to control motor disruption in Parkinson’s. A major limitation with many stimulation methods, however, is that the protocol is static while the brain is plastic—over time, brain responses to stimulation may no longer elicit what was intended as the brain naturally changes.
Review written by Sara Camilli (QCB) and Adelaide Minerva (PNI)
As we go about our daily lives, we often do not consciously think about all the real-world landmarks that we use to position ourselves in space. Yet, as we walk to our local coffee shop or go for a jog in the park, our brain is continuously updating its internal representation of our location, which is critical to our ability to navigate the world. However, we also know that humans and a number of animals can update this internal representation of their position in space even in the absence of external cues. This phenomenon, known as path integration, involves interaction between the parietal cortex, medial entorhinal cortex (MEC), and hippocampus regions of the brain. Prior work has shown that grid cells in the MEC have firing fields that are arrayed in a hexagonal lattice, tiling an environment. Further, there is evidence of inputs to the MEC that encode the velocity at which an animal is moving, which can be used to update the animal’s internal representation of its position. Together, these features support a role of the MEC in path integration.
Review written by Crystal Lee (PSY) and Adelaide Minerva (PNI)
Recently, the term “fake news” has been solidified as a colloquial term. Indeed, it seems the world has seen an increase in the spread of misinformation. What is particularly troubling about this trend is that psychology studies show that increased exposure to information (both true and false) increases our beliefs about its truthfulness, and what we believe to be true impacts our behavior in important ways (e.g., voting). When we consider the spread of “fake news”, how do we know what is true, and how do we protect ourselves from misinformation?