"Scientists reported on Wednesday that they had taken a significant step toward understanding the cause of schizophrenia, in a landmark study that provides the first rigorously tested insight into the biology behind any common psychiatric disorder. The researchers pieced together the steps by which genes can increase a person’s risk of developing schizophrenia. That risk, they found, is tied to a natural process called synaptic pruning, in which the brain sheds weak or redundant connections between neurons as it matures. During adolescenceand early adulthood, this activity takes place primarily in the section of the brain where thinking and planning skills are centered, known as the prefrontal cortex. People who carry genes that accelerate or intensify that pruning are at higher risk of developing schizophrenia than those who do not, the new study suggests."
"The observable universe consists of the galaxies and other matter that can, in principle, be observed from Earth at the present time because light and other signals from these objects have had time to reach Earth since the beginning of thecosmological expansion. Assuming the universe is isotropic, the distance to the edge of the observable universe is roughly the same in every direction. That is, the observable universe is a spherical volume (a ball) centered on the observer. Every location in the Universe has its own observable universe, which may or may not overlap with the one centered on Earth.
The word observable used in this sense does not depend on whether modern technology actually permits detection ofradiation from an object in this region (or indeed on whether there is any radiation to detect). It simply indicates that it is possible in principle for light or other signals from the object to reach an observer on Earth. In practice, we can see light only from as far back as the time of photon decoupling in the recombinationepoch. That is when particles were first able to emit photons that were not quickly re-absorbed by other particles. Before then, the Universe was filled with a plasmathat was opaque to photons."
The Michigan Department of
Environmental Quality failed to ensure the water was treated for its
corrosiveness.
The Flint River water turned out to be
more corrosive than the water Flint received from Detroit -- so corrosive, in
fact, that in October 2014, General Motors opted toquit
using itto avoid
corroding parts in its engine plant. Corrosiveness is a problem because Flint,
like many American cities, has water pipes that are made from lead, which can
leach into the water and poison people who drink it.
Back in 2011, Flint had commissioned
an evaluation of Flint River water, the results of which indicated it would
need to be treated with phosphates to reduce its corrosiveness. Two years
later,according
to the Detroit Free Press, a Flint official forwarded that
information to the Michigan Department of Environmental Quality, which is
responsible for ensuring that Flint follows the federal Safe Drinking Water
Act. But the MDEQ didn't do its job.
As Miguel Del Toral, an expert with
the Environmental Protection Agency who was investigating local complaints
about the water, explained in a June 2015 memo: "Recent drinking water
sample results indicate the presence of high lead results in the drinking
water, which is to be expected in a public water system that is not providing
corrosion control treatment. The lack of any mitigating treatment for lead is
of serious concern for residents that live in homes with lead service lines or
partial lead service lines, which are common throughout the City of
Flint."
Stereotype threat is a situational predicament in which people are or feel themselves to be at risk of confirming negative stereotypes about their social group.[1] Since its introduction into the academic literature, stereotype threat has become one of the most widely studied topics in the field of social psychology.[2] Stereotype threat has been shown to reduce the performance of individuals who belong to negatively stereotyped groups.[3] If negative stereotypes are present regarding a specific group, group members are likely to become anxiousabout their performance, which may hinder their ability to perform at their maximum level. For example, stereotype threat can lower the intellectual performance of African Americanstaking the SAT test used for college entrance in the United States, due to the stereotype that African Americans are less intelligent than other groups.[4] Importantly, the individual does not need to subscribe to the stereotype for it to be activated. The specific mechanism through which anxiety (induced by the activation of the stereotype) decreases performance is by depleting working memory (especially the phonological aspects of the working memory system).[5]
Stereotype threat is a potential contributing factor to long-standing racial and gender gaps in academic performance. It may occur whenever an individual's performance might confirm a negative stereotype because stereotype threat is thought to arise from a particular situation, rather than from an individual's personality traits or characteristics. Since most people have at least one social identity which is negatively stereotyped, most people are vulnerable to stereotype threat if they encounter a situation in which the stereotype is relevant. Situational factors that increase stereotype threat can include the difficulty of the task, the belief that the task measures their abilities, and the relevance of the stereotype to the task. Individuals show higher degrees of stereotype threat on tasks they wish to perform well on and when they identify strongly with the stereotyped group. These effects are also increased when they expect discrimination due to their identification with a negatively stereotyped group.[6] Repeated experiences of stereotype threat can lead to a vicious circle of diminished confidence, poor performance, and loss of interest in the relevant area of achievement.[7]
Proponents of stereotype threat have been criticized for exaggerating its importance as an explanation of real-world performance gaps[8][9] and misrepresenting evidence as more conclusive than it is.[10][11] One review has voiced concerns that the effect has been over-estimated and that the field suffers from publication bias.[12]
The opposite of stereotype threat is stereotype boost, which is when people perform better than they otherwise would have, because of exposure to positive stereotypes about their social group. A variant of stereotype boost is stereotype lift, which is people achieving better performance because of exposure to negative stereotypes about other social groups.[1]
"A trove of bones hidden deep within a South African cave represents a new species of human ancestor, scientists announced Thursday in thejournal eLife.Homo naledi, as they call it, appears very primitive in some respects—it had a tiny brain, for instance, and apelike shoulders for climbing. But in other ways it looks remarkably like modern humans. When did it live? Where does it fit in the human family tree? And how did its bones get into the deepest hidden chamber of the cave—could such a primitive creature have been disposing of its dead intentionally?"
This is the story of one of the greatest fossil discoveries of the past half century, and of what it might mean for our understanding of human evolution.
"The Braided Stream - From National Geographic
When a major new find is made in human evolution—or even a minor new find—it’s common to claim it overturns all previous notions of our ancestry. Perhaps having learned from past mistakes, Berger doesn’t make such assertions for Homo naledi—at least not yet, with its place in time uncertain. He doesn’t claim he has found the earliest Homo, or that his fossils return the title of “Cradle of Humankind” from East to South Africa. The fossils do suggest, however, that both regions, and everywhere in between, may harbor clues to a story that is more complicated than the metaphor “human family tree” would suggest.
“What naledi says to me is that you may think the record is complete enough to make up stories, and it’s not,” said Stony Brook’s Fred Grine. Maybe early species of Homo emerged in South Africa and then moved up to East Africa. “Or maybe it’s the other way around.”
Berger himself thinks the right metaphor for human evolution, instead of a tree branching from a single root, is a braided stream: a river that divides into channels, only to merge again downstream. Similarly, the various hominin types that inhabited the landscapes of Africa must at some point have diverged from a common ancestor. But then farther down the river of time they may have coalesced again, so that we, at the river’s mouth, carry in us today a bit of East Africa, a bit of South Africa, and a whole lot of history we have no notion of whatsoever. Because one thing is for sure: If we learned about a completely new form of hominin only because a couple of cavers were skinny enough to fit through a crack in a well-explored South African cave, we really don’t have a clue what else might be out there."
Just as a group of celestial bodies is a galaxy and a group of galaxies is a cluster, a group of galactic clusters is known as a "supercluster" (not very original, I know).
Scientists had previously thought that our own galaxy was positioned at the edge of the Local Supercluster that itself was centered on the Virgo Cluster, which they believed to be about 100 million light-years wide. That's the equivalent of 1.03461597 × 1022 American football fields (or so Google tells me), which is such a ridiculously huge number that it probably didn't do anything to help you understand the scope of it.
But that's OK, because that number was off. Like, waaaaaaay off. So throw away all your preconceived notions of incomprehensibly exponential intergalactic football fields and say hello to your new home supercluster!
The Laniakea Supercluster encompasses 100,000 galaxies stretched out over 160 megaparsecs (520 million light-years). It has the approximate binding mass of 1017 solar masses, or a hundred thousand times that of our Galaxy, which is almost the same as that of the massive Horologium Supercluster. It consists of four subparts, which are known previously as separate superclusters:
The most massive galaxy clusters of Laniakea are Virgo, Hydra, Centaurus, Abell 3565, Abell 3574, Abell 3521, Fornax, Eridanus and Norma. The entire supercluster consists of approximately 300 to 500 known galaxy clusters and groups. The real number may be much larger, because some of these are transversing the Zone of Avoidance, making them essentially undetectable.
Superclusters are some of the universe’s largest structures, and have boundaries that are difficult to define, especially from the inside. The team used radio telescopes to map the motions of a large collection of local galaxies. Within a given supercluster, most galaxy motions will be directed inward, toward the center of mass. In the case of Laniakea, this gravitational focal point is called the Great Attractor, and influences the motions of our Local Group of galaxies (where our Milky Way Galaxy resides) and all others throughout our supercluster. Unlike its constituent clusters, Laniakea is not gravitationally bound and is projected to be torn apart by Dark energy.[5]
