Monday, July 24, 2017

5,000 Year Natural Tsunami Record Reveals That They Are Unpredictable

There is a little bit of method to the madness of when a tsunami will strike, but not much, according to the longest, cleanest continuous natural record of tsunami activity yet discovered. 
"Tsunamis are not evenly spaced through time," says Charles Rubin, the study's lead author and a professor at the Earth Observatory of Singapore, part of Nanyang Technological University. "Our findings present a worrying picture of highly erratic tsunami recurrence. There can be long periods between tsunamis, but you can also get major tsunamis that are separated by just a few decades." 
The discovery, reported in the current issue of Nature Communications, logs a number of firsts: the first record of ancient tsunami activity found in a sea cave; the first record for such a long time period in the Indian Ocean; and the most pristine record of tsunamis anywhere in the world. 
The discovery was made in a sea cave on the west coast of Sumatra in Indonesia, just south of the city of Banda Aceh, which was devastated by the tsunami of December 2004. The stratigraphic record reveals successive layers of sand, bat droppings and other debris laid down by tsunamis between 7,900 and 2,900 years ago. The stratigraphy since 2,900 years ago was washed away by the 2004 tsunami.

. . .
The record indicates that 11 tsunamis were generated during that period by earthquakes along the Sunda Megathrust, the 3,300-mile-long fault running from Myanmar to Sumatra in the Indian Ocean. The researchers found there were two tsunami-free millennia during the 5,000 years, and one century in which four tsunamis struck the coast. In general, the scientists report, smaller tsunamis occur relatively close together, followed by long dormant periods, followed by great quakes and tsunamis, such as the one that struck in 2004.
From here. The paper that is the source for this article is:

Friday, July 21, 2017

A Spiral Galaxy's Central Black Hole's Mass Is Accurately Measured By Its Spiral Arms

After carefully analysing a larger sample of galaxies, imaged by an array of space telescopes, the researchers observed an unexpectedly strong relationship, and one which predicts lower mass black holes in galaxies with open spiral arms (types Sc and Sd). 
"The strength of the correlation is competitive with, if not better than, all our other methods used to predict black hole masses," says Dr Davis. "Anyone can now look at an image of a spiral galaxy and immediately gauge how massive its black hole should be."
From here.  The source and its abstract are as follows:
We have conducted an image analysis of the (current) full sample of 44 spiral galaxies with directly measured supermassive black hole (SMBH) masses, MBH, to determine each galaxy’s logarithmic spiral arm pitch angle, ϕ. For predicting black hole masses, we have derived the relation: log (MBH/M⊙) = (7.01 ± 0.07) − (0.171 ± 0.017)[|ϕ| − 15°]. The total root mean square scatter associated with this relation is 0.43 dex in the log MBH direction, with an intrinsic scatter of 0.30 ± 0.08 dex. The MBH–ϕ relation is therefore at least as accurate at predicting SMBH masses in spiral galaxies as the other known relations. By definition, the existence of an MBH–ϕ relation demands that the SMBH mass must correlate with the galaxy discs in some manner. Moreover, with the majority of our sample (37 of 44) classified in the literature as having a pseudobulge morphology, we additionally reveal that the SMBH mass correlates with the large-scale spiral pattern and thus the discs of galaxies hosting pseudobulges. Furthermore, given that the MBH–ϕ relation is capable of estimating black hole masses in bulge-less spiral galaxies, it therefore has great promise for predicting which galaxies may harbour intermediate-mass black holes (IMBHs, MBH < 105 M⊙). Extrapolating from the current relation, we predict that galaxies with |ϕ| ≥ 26°7' should possess IMBHs.
Benjamin L. Davis, Alister W. Graham, Marc S. Seigar. "Updating the (Supermassive Black Hole Mass) – (Spiral Arm Pitch Angle) Relation: A Strong Correlation for Galaxies with Pseudobulges." Monthly Notices of the Royal Astronomical Society (July 19, 2017) DOI: 10.1093/mnras/stx1794

New Observations Disfavor Fuzzy Dark Matter

Observations of the absorption of photons by neutral hydrogen in deep space strongly disfavor a new dark matter theory called "Fuzzy Dark Matter" while being consistent with the Cold Dark Matter hypothesis (that is itself disfavored by smaller scale structure observations by astronomers). 

In the Fuzzy Dark Matter (FDM) model, dark matter is deemed composed of ultralight bosons provided with a non-negligible pressure at small scales, and  dark matter has higher particle velocities than it does in cold dark matter (CDM) models. FDM models overlap with Axion Dark Matter models.

More Evidence Of Archaic Admixture In Africa

Scientists have located a gene in some sub-Saharan Africans that governs salvia consistency, which is absent from other modern humans (in and out of Africa), form Neanderthals and from Denisovans. 

Given the extent to which it is divergent, the most likely explanation, which supported by other previous research indicating genetic traces of archaic admixture in Africans, is that the ancestors of the people who bear this gene had children with to be determined archaic hominin species in Africa. But, since we have no ancient DNA from any archaic hominin species in Africa, it is hard to know which archaic hominin species introgressed into the modern human genome in Africa.

There Have Been A Small Number Of People With Blue Skin

There is a recessive genetic condition that causes people to have blue tinted skin and purple lips, but because it is rare, it ordinarily isn't observed outside inbred communities such as one that existed in the early to mid-20th century in Eastern Kentucky in the Fugate family. These people were known as the Blue Fugates.
The Fugate family first settled in Kentucky in 1820. Martin Fugate and his wife Elizabeth Smith came to Troublesome Creek, an out-of-the-way region of Appalachia. According to some sources, Fugate was blue himself, though this has been disputed. Whatever his color, his offspring ended up with an unusual appearance: his son Zachariah was born with blue skin, and so were three more of their seven children. . . . 
The Fugates had a genetic defect that resulted in a condition called methemoglobinemia, which means their blood didn't carry as much oxygen around the body. This makes the blood darker, which in turn causes the skin of white people to appear blue, and their lips to look purple. In addition, arterial blood looks chocolate brown rather than red. People with methemoglobinemia have higher levels of methemoglobin in their blood; they may have 10-20 percent, versus the average person's one percent. The Fugates' very blood was different from that of their neighbors. . . . Methemoglobinemia can cause developmental delay and seizures, but despite the intense appearance of their blue skin and purple lips, none of the Fugates suffered poor health or lived in pain. The condition had only a cosmetic effect, though the family endured psychological pain from their outsider status. Each of the Blue Fugates lived to a ripe old age. . . .

After interviewing the Fugates, Cawein concluded that their blood must be missing a crucial enzyme. To trigger the blood's natural processes, the doctor decided to inject the affected family members with methylene blue, a dye. The cosmetic results were nearly instant. Talking about the experience years later, Cawein said that the treated family members were thrilled to see the blue fade from their skin: "For the first time in their lives, they were pink." The solution really was that easy. The effects of the dye were temporary, but Cawein supplied the Fugates with methylene blue tablets to take every day.
The conditions was particularly stigmatizing because it was understood to be connected with undue inbreeding (which was, in fact, present in the family).