Researchers at UC Berkeley are studying ancient Roman concrete in an effort to come up with a durable, yet green concrete. Shipping was instrumental to the expansion and sustainability of the Roman Empire. Using volcanic ash and seawater, the Romans developed concrete that has withstood the harsh marine environment for over 2,000 years. Scientist used the Advanced Light Source at Lawrence Berkeley National Laboratory (Berkeley Lab) to look at fine structures in the Roman concrete for the first time.
Roman concrete has a smaller carbon footprint because the modern cement (Portland cement) burns calcium carbonate (limestone) and clays at 1,450 deg C while lime used in Roman concrete requires only two thirds of that.
If Roman concrete is so good, why is it not still used? As the Roman Empire declined, the need for shipping and therefore the need marine concrete diminished. Also, modern concrete takes a fraction of the time to cure, compared to Roman concrete.
Edit
I should have defined what concrete is. Concrete is a composite material, made of “filler” (e.g. pebbles) and a binder (cement). So what is cement? More importantly, what is Portland cement, which is mentioned in the article and is the most common type of cement used. Portland cement is calcium silicates mixed with aluminum and iron containing clinker phases. (http://en.wikipedia.org/wiki/Portland_cement). So what are clinker phases? Clinkers are balls of sintered (baked) material made by taking a mixture of materials and heating them with very high heat. So the big difference between Roman concrete and modern concrete is really the clinker, not so much the filler. Also note that Roman concrete does not use steel reinforcing bars (rebar), so modern concrete has much higher tensile strength.
Pertussis or whooping cough is caused by the bacterium
Bordetella pertussis. It’s called whooping cough because after a coughing fit, an infected person makes a whooping sound when they try to catch their breath. Babies less than a year old can die from pertussis.
Whooping cough, or pertussis, has exploded in the United States in recent years. A new study confirms what scientists have suspected for some time: The return of the disease is caused by the introduction of new, safer vaccines 2 decades ago. Although they have far fewer side effects, the new shots don’t offer long-lived protection the way older vaccines do.
The disease seemed to have disappeared by the 1970s but has come back in the past decade or two. Evidence suggest that the reoccurrence is due to the switch from a vaccine based on the whole-cell bacterium to a new vaccine that has just parts of the bacterium. The newer virus has less side effects but apparently doesn’t offer long term protection. The newer vaccine was developed because the chemicals used to kill the pertussis for the vaccine where causing side effects.
During the 1980s, U.S. parents successfully sued manufacturers, alleging that the whole-cell vaccine also caused long-term brain damage. A 1991 Institute of Medicine report concluded that this was unproven, but by then many pertussis vaccine manufacturers had withdrawn from the market, leading Congress to create a federal vaccine injury compensation program for families who could show a strong case for vaccine damage.
Three studies have shown that the new acellular vaccination, i.e., one based on parts of the bacterium, no the whole cell, is less effective (long lasting) compared to the older vaccine.
Comparative Effectiveness of Acellular Versus Whole-Cell Pertussis Vaccines in Teenagers in Pediatrics: http://goo.gl/SE6dZ , Number and Order of Whole Cell Pertussis Vaccines in Infancy and Disease Protection in JAMA http://goo.gl/H02wy , Reduced Risk of Pertussis Among Persons Ever Vaccinated With Whole Cell Pertussis Vaccine Compared to Recipients of Acellular Pertussis Vaccines in a Large US Cohorthttp://goo.gl/TBa4H
So why does the whole-cell based vaccine work better and why switch? The whole-cell based vaccine likely works better because there is more of the cell that is presented to the immune system to generate anti-bodies. Also, as the pertussis bacteria mutate, the new vaccine is likely to have less overlap with the mutated version. The older, whole-cell based version is likely to have antigens that are still effective, i.e., still in the mutated version.
Why is this important? There has been an increase in whooping cough out breaks in the US and measles in the UK. http://goo.gl/8xRa7 via Philip Plait and http://goo.gl/fXzB1
It’s dangerous when misinformation and conspiracy theories affect policy and decision making. If more people are scared into not getting vaccinated, then herd immunity is compromised.
Using science, we understand that the increase in whooping cough infections is at least partially explained by the switch to the new vaccine, based on parts of the Bordetella pertussis and not the whole cell. It is also partially explained by diminished herd immunity by unvaccinated people/children.
Finally, I’ll point you to as disturbing story about anti-vaxxers going after a family that lost their infant to whooping cough. http://goo.gl/saspV
My father has a degree in comparative religion. I’ve always been fascinated by the intersection of metaphysics and science. Dr. Weinberg talks about wave theory, the big bang theory, quantum mechanics, and more. It’s a long discussion ~1 hour 14 min. Cliff Harvey does a great job giving some of his insight on the discussion.
This is a great discussion exploring all kinds of questions, especially touching on some points of contact between physics and the ‘grand’ religious or quasi-religious questions, including the issue of fine-tuning of physical constants, anthropic selection from a larger reality, what we know about the early universe from experiments, and what we think we know. Its clear from the thunder in the first few minutes that they’ve angered the Gods….
In case you weren’t aware, Steven Weinberg is one of the main co-fathers of the Standard Model, a Nobel laureate, and wrote the book (all 3 volumes) on quantum field theory, so as someone very familiar with the currently most fundamental frameworks he’s among the most trustworthy and well-prepared to discuss these matters.
One of the physical issues they tackle early on is ‘dark energy’ or the vacuum energy. Here Weinberg does a good job clarifying some of the usual confusions often found in the press. We cannot, strictly speaking, calculate the value of the vacuum energy, but what we can do is calculate contributions to it, from fluctuations in various known fields down to whatever distance scales we decide to trust our current model, with the Planck scale being the absolute limit. When this is done we get an answer something around ~10^120 times too high (or possibly more like ~10^60 if there are some low-scale SUSY partners). But strictly speaking this is not a “conflict with experiment” because there is still the freedom to add a simple constant to the whole thing. The assumption that this “constant part” is zero leads to a meaningful constraint on the particle content and ultimate high-energy laws of the universe, but so far we unfortunately don’t know how to do away with that extra freedom. I agree with Weinberg that it still seems natural to expect that (at least most of) this discrepancy will be addressed by contributions from new laws which must take over by the Planck scale at the latest, and also probably from more ordinary particles which haven’t yet been discovered. Still, absent some new and currently unknown principle, this remains a primary candidate for anthropic selection.
They spend some time on the “nightmare scenario” of not finding anything new at the LHC. I don’t plan on getting very worried about this until we see a fair amount of 14 TeV data analyzed, but more importantly, its not a scientist’s place to complain about the laws of nature. I agree that it might not be as enjoyable a time to be a theorist if we don’t find something else, but there is still so much good work to be done in understanding the current frameworks more deeply. Also, its important to recognize that negative results are important too, they constrain future attempts at model building in important ways. But in my opinion there is no avoiding the obvious fact that physics is objectively and dramatically closer to its defined goal of describing the fundamental laws of the universe, and at some point it just becomes unrealistic and unscientific to expect that this period of science has to be directly analogous to the one that existed 150 years ago. They’re qualitatively quite different. The process of science is all about trying to find new ways to test our current best understanding, and in some ways even to try and break it, but that doesn’t mean we’re entitled to a rewriting of all the laws every few years, as a startling number of people seem to believe. That is exactly the kind of unhealthy attachment to an idea (or feeling) that the skepticism that defines science is supposed to dissuade you from. The very assumption that there are laws of the universe implies that this scientific process will inevitably become more stable over time, particularly on the most fundamental end.
Around 54:00 they also venture into the question of interpreting quantum mechanics, and here its extremely clear that there inevitably should be a conflict between your scientific understanding of the fundamental laws and your intuitive understanding of newtonian physics that you use to walk down the street. Something would have to be wrong otherwise. Essentially, because any of the hypotheses that would prevent the “unsettling” implications of QM at human scales require some kind of dramatic revision of its content, even though no evidence supports such a revision. Here Weinberg himself confesses that he thinks the “best” outcome would be to find out that there is some mechanism that breaks QM as we know it when small systems interact with large systems, though he is at least straightforward about the lack of any support from evidence. He himself mentions the many entanglement experiments have proven that quantum mechanics does still operate at distances as far as meters or even kilometers, and should work to any arbitrary distance. I don’t think its rational to “hope” for a way to circumscribe quantum mechanics in this way.This is a big topic I’ve worked on, posted on, and will post again on…
Anyway those are just a few responses to a very far-reaching conversation.
Hemoglobin is the oxygen carrying protein in our red blood cells (RBC), i.e., it is intracellular. What that means is, unlike our blood, the bobbit worm has free hemoglobin; just floating around. That might not seem amazing to you but here’s why it is amazing. In mammalian blood, hemoglobin is protected from oxidation inside the RBC by many other proteins You’ve seen iron rust. That’s oxidation and hemoglobin’s oxygen binding component has iron. When iron is oxidized it can generate free radicals which are toxic. That’s why you hear people recommending anti-oxidant rich fruits/vegetables. When iron is oxidized and creates free radicals it is called Fenton chemistry.
Additional interesting info on the bobbit worm from Wiki, which is where the image is from.
Armed with sharp teeth, it is known to attack with such speeds that its prey is sometimes sliced in half. Although the worm hunts for food, it is omnivorous. It is also covered in bristles that are capable of a sting that results in permanent numbness in humans.
Edit Many invertebrates have extracellular hemoglobin. I haven’t had time to find out what mechanism the bobbit worm uses to project its heme from oxidation.
Here’s an interesting NPR piece on hagfish slime (http://www.theworld.org/2013/03/hagfish-clothes/). Scientists have been looking for strong yet lightweight fibers, preferably from a renewable source. For example see my post about spider silk.
Too busy for a longer post today. Don’t forget to circle ScienceSunday if you haven’t already. Mention the curators, Rajini Rao Allison Sekuler Buddhini Samarasinghe Robby Bowles and me, so that your #ScienceSunday post doesn’t get lost in never-never-land.
Erin Kane’s post Convergent Evolution: how cool is that? (http://goo.gl/47I1C) reminded me that hyena females are dominant, e.g., alfa females. Erin’s post also reminded me of our collaboration on work similar to the video.
OK, back to hyenas and hormones. Spotted hyena females release androgen to their offspring, which makes them more aggressive (think about what you’ve read about athletes using anabolic steroids). This added aggression is important to improve their chance of getting a meal, and therefore survive. It also makes the males more sexually active, early on. This is important as they need practice, to deal with the complicated copulation of hyenas. Female hyenas, especially the spotted hyena, have a pseudo-phallus due to the androgen that they received from their mother, i.e., the clitoris is enlarged. You can read more here: http://goo.gl/g6DA6
Brains: Another interesting fact about the spotted hyena is that they have a larger brain volume when compared to the striped hyena, brown hyena, and aardwolves. The spotted hyena also possesses a larger anterior cerebrum volume relative to total brain volume than is found in the other hyena species; this region is composed primarily of frontal cortex. These data are consistent with the idea that expansion of the frontal cortex is driven by the demands of processing cognitive information associated with complex social lives, but other factors may drive the evolution of large brains in hyaenids.
Brain size and social complexity: a computed tomography study in Hyaenidae.
Sakai ST, Arsznov BM, Lundrigan BL, Holekamp KE.
Brain Behav Evol. 2011;77(2):91-104. doi: 10.1159/000323849. Epub 2011 Feb 17.
Symbiotic relations: One more science tidbit, bacteria have a symbiotic relationship with hyenas. The diversity in the bacteria can aid hyenas in identifying members of the same social group based on how the structure of the bacteria affects the odor of the hyena’s scent gland.
Evidence for a bacterial mechanism for group-specific social odors among hyenas.
Theis KR, Schmidt TM, Holekamp KE.
Sci Rep. 2012;2:615. doi: 10.1038/srep00615. Epub 2012 Aug 30.
Prosopagnosia, or Face Blindness, is a largely unrecognized disorder. (Yes, yes, I know…) Various estimates hold that between 2% and 10% of the population exhibit some degree of this inability to recognize familiar faces, yet few people have even heard of it, and as a result many sufferers are hesitant to even mention they have difficulty for fear of embarrassment or discrimination.
Dr. Sarah Bate of the Centre for Face Processing Disorders at Bournemouth University is leading a campaign to raise greater awareness of Prosopagnosia in the U.K. House of Commons. She has an online petition available through www.prosopagnosiaresearch.org which I highly encourage U.K. readers to go sign. The attached article has further information.
For U.S. readers who wish to know more about prosopagnosia, the Prosopagnosia Research Centers at Dartmouth College, Harvard University, and University College London have excellent information at www.faceblind.org including their biannual Face to Face newsletter.
As a prosopagnosic myself, I am always interested in the current state of research and I hope to enlighten others about this condition. So many people don’t even know this disorder exists, even those suffering from it in many cases. Greater awareness can help out both by increasing research and reducing any perceived stigma in admitting to having prosopagnosia.
The first figure below is from:
The anatomic basis of the right face-selective N170 IN acquired prosopagnosia: A combined ERP/fMRI study
fMRI and ERP were used to gain insight into a region of the brain associated with the acquired form of prosopagnosia. Event-related potentials (ERP) are measured with electroencephalography (EEG). http://en.wikipedia.org/wiki/Event-related_potential
ScienceSunday co-curator Chad Haney has posted about fMRI frequently, and most recently here: http://goo.gl/xhc6T
An interesting point of the first figure is that the location of the lesion isn’t necessarily where the investigators are looking in terms of the functional image and as mention by Chad before, the figure demonstrates the variability in BOLD MRI (fMRI).
The remaining three figures are from
Congenital prosopagnosia: multistage anatomical and functional deficits in face processing circuitry.
V Dinkelacker et al
J Neurol. 2011 May;258(5):770-82. doi: 10.1007/s00415-010-5828-5. Epub 2010 Dec 1.
The interesting finding there is that facial recognition is not as impaired when it comes to negative faces. The images also show that unlike the first study linked here, the congenital prosopagnosia patients lack any lesion. They hypothesize that congenital prosopagnosia is due to a network dysfunction and that the lingual gyrus plays a substantial role. The lingual gyrus has to do with visual processing, especially letters. The name is due to its physical apperance as it looks like a tongue. It is not associated with speech.
Happy birthday Rajini Rao have a #punderstorm day, especially #ScienceEveryday with the #Incorrigibles.
#Wolverine2WonderWomanHappyBD
Originally shared by Buddhini Samarasinghe
Interfering with RNA
A birthday tribute to someone I really admire here on G+, who is an amazing mentor and friend. Happy Birthday Rajini Rao, hope you have a wonderful year ahead and it’s been a pleasure knowing and working with you on our many projects together on G+!
A few days ago during our ENCODE Hangout on Air (http://goo.gl/H6KDE), I mentioned microRNAs. I wanted to write a post today about the general mechanism of how a gene can be ‘silenced’ through a process known as RNA interference.
• As we explained during the Hangout, the Central Dogma of Molecular Biology is DNA –> RNA –> Protein. This means the DNA blueprint makes a sequence-specific copy of RNA, which in turn acts as a blueprint for a specific sequence of amino acids which make up a protein.
• So imagine if you could somehow destroy the RNA blueprint (known as the messenger RNA, or mRNA) for a particular protein. This would prevent the protein from being made – no blueprint, no protein. This is what RNA interference, or gene silencing is.
• It was first observed by plant scientists working on petunias in 1990. They were trying to make the color of the flower darker, so they introduced extra copies of the gene chalcone synthase, a key enzyme involved in the synthesis of pink and violet flower pigment (http://goo.gl/2A0Wk). Their logic makes sense – adding more copies of the gene for chalcone synthase should make more protein, which in turn should make flowers darker. But when they did the experiment, instead of darker flowers they got lighter flowers, or fully or partially white flowers absent of any color (see image below). Clearly, introducing extra copies of the chalcone synthase gene was decreasing the activity of chalcone synthase.
• Similar phenomena were reported in fungi, and also in plant viruses. However, it was not until 1998 when Andrew Fire and Craig Mello formally identified the process as ‘RNA interference’ in their groundbreaking work on the nematode worm Caenorhabditis elegans (http://goo.gl/XYId1). They injected sequence specific double-stranded DNA into the worm and then observed the silencing of the target gene (the mRNA blueprint went missing, and therefore so did the protein). This was the first time that double-stranded DNA was identified as the causative agent for the gene silencing phenomenon.
• The discovery completely revolutionized biology; Fire and Mello were awarded the Nobel Prize just eight short years after the publication of their work, which is very unusual (usually Nobel-prizes recognize work that is several decades old!). The work was so important because now we could silence any gene to see the effect it would have on the organism.
• Why is this important? Imagine you have a car, and you want to learn the function of the different parts. If you remove (or silence!) a wheel, the car cannot move. Therefore you can conclude that the wheel is necessary for motion. The same could be done within the organism; silence a gene, and you notice that the animal is now impaired in movement, so you can conclude that the gene may be involved in muscle development or coordination. Silence another gene, and you notice the eggs look strange, and you conclude that the gene was involved in egg development. RNA interference allowed scientists to assign a function to a gene; this has been and will remain an invaluable tool in molecular biology for decades ahead.
All the original research papers I’ve cited above are #openaccess
Hemoglobin is the oxygen carrying protein in our red blood cells (RBC), i.e., it is intracellular. What that means is, unlike our blood, the bobbit worm has free hemoglobin; just floating around. That might not seem amazing to you but here’s why it is amazing. In mammalian blood, hemoglobin is protected from oxidation inside the RBC by many other proteins You’ve seen iron rust. That’s oxidation and hemoglobin’s oxygen binding component has iron. When iron is oxidized it can generate free radicals which are toxic. That’s why you hear people recommending anti-oxidant rich fruits/vegetables. When iron is oxidized and creates free radicals it is called Fenton chemistry.
Additional interesting info on the bobbit worm from Wiki, which is where the image is from.
Armed with sharp teeth, it is known to attack with such speeds that its prey is sometimes sliced in half. Although the worm hunts for food, it is omnivorous. It is also covered in bristles that are capable of a sting that results in permanent numbness in humans.
Edit Many invertebrates have extracellular hemoglobin. I haven’t had time to find out what mechanism the bobbit worm uses to project its heme from oxidation.
