Tag: images

Chromatin Loops

“It’s quite spectacular that the structure of an entire chromosome would rely on a small DNA sequence somewhere in the middle”. Scientists have long suspected that abnormal genome folding may cause diseases, and several new studies have identified links between genome architecture and biological development. A rearrangement of DNA in a noncoding region of the genome causes limb malformations during development by changing chromatin folding. Other researchers are using CRISPR to investigate whether changes to genome architecture affects the ability of parasites like Trypanosoma, the cause of African sleeping sickness, to evade the immune system. It’s becoming apparent that in the genome, “nothing makes sense except in 3D.”

30 days to Mars

ProjectRho has round trip space mission times based on 3 types of rocket missions and 3 levels of constant acceleration. Constant acceleration could be achieved with an antimatter catalyzed fusion propulsion system like Positron Dynamics is developing

15 days 1 way to Mars with a constant 0.01 G acceleration and deceleration.
6 days 1 way to Mars with a constant 0.1G acceleration and deceleration.
2 days 1 way to Mars with a constant 1G acceleration and deceleration.


2022-02-19: It is also possible to get to Mars in 45 with Laser Thermal Propulsion: A Earth-based Laser heats up onboard propellant. This has very promising characteristics:

For lower velocity missions within the solar system, coupling the laser to the spacecraft via a reaction mass (i.e., propellant) is a more efficient way to use the delivered power than reflecting it off a lightsail. Reflecting light only transfers a tiny bit of the photon’s energy to the spacecraft, but absorbing the photon’s energy and putting it into a reaction mass results in greater energy transfer. The greater power that can be delivered results in greater thrust, so a more intense propulsive maneuver can be performed nearer to Earth. The closer to Earth the propulsive burn is, the smaller the laser array needs to be in order to keep the beam focused on the spacecraft, making it more feasible as a near-term demonstration of directed energy propulsion. The scaled-up version of our design (Mission Mars 2a) intended for crewed missions used a 40-ton spacecraft derived from the Orion capsule and European Service Module. The greater payload requires a more powerful (4 GW) laser to effectuate the same 45-day transit to Mars, but the laser array occupies the same 10-m footprint on earth.
The other mission we considered was a cargo mission (Mission Mars 2b). Robert Zubrin often makes the point that—even if advanced propulsion capable of high thrust and high specific impulse was available—he would still opt for a 6-month free-return trajectory and use the enhanced propulsion capability to bring more payload. So, the Mars 2b mission uses the performance of laser thermal propulsion to maximize the amount of cargo that could be brought to Mars with a Hohmann-like transfer, and shows that the payload could be increased by a 10x over what a Centaur upper stage—with the same mass of propellant—could throw to Mars.

40 shipwrecks

The Black Sea Maritime Archaeology Project wasn’t looking for shipwrecks. Its brief is to survey the Bulgarian coast of the Black Sea for data about the rise water levels after the last Ice Age 20 ka ago. To accomplish this aim, marine archaeologists have been scanning the seabed using cutting edge Remotely Operated Vehicles that can detect land surfaces underneath what is now the Black Sea but in prehistory were on dry land. They’ve also taken core samples, laser scanned and filmed the sea bed both in video and with high resolution 3D photogrammetry. A felicitous but entirely unplanned side-effect of this exceptionally thorough geophysical survey is the discovery of more than 40 historic shipwrecks, including ancient Byzantine, medieval and Ottoman ships. Some of them may even be the first of their kind ever found, previously known only from documentary sources. Such a large, varied group of shipwrecks from different periods will give archaeologists a whole new understanding of trade and maritime links between towns on the coast of the Black Sea.

this is unprecedented, and very awesome

Constellation Park

earning your keep after you die

Imagine the Manhattan Bridge twinkling from underneath with 100s of small pods filled with decaying biomass – the final resting place of many former New Yorkers, shining like stars in an otherwise dark sky. There, you might lay flowers near a pod containing the remains of a loved one, until decomposition finishes its course and all that remains is a container to keep as a remembrance. This is the vision that is Constellation Park, a shiny new cemetery proposed by DeathLab, a trans-disciplinary research and design space at Columbia University.

Harbor Ring

I realized that there was a disconnect between the idea of a cars-only crossing and the reality evolving in the region. Bikes are taking off all over the city. We now have waterfront development all along the harbor with parks and bike paths. It’s a whole rebirth, the “new New York.” And the powers that be have repeatedly rejected bike access on the bridge. We started thinking about how we could recast the idea of a shared-use path on the bridge. I’m an urban and regional planner by training, but I’ve been in the family hardware business, and so I thought, “We have to take a marketing approach to repackage Verrazano access.” It’s the missing link in the Harbor Ring. We became the Harbor Ring Committee.

Postmortem Avatar

When her best friend died, she rebuilt him using artificial intelligence.

It has been less than a year since Mazurenko died, and he continues to loom large in the lives of the people who knew him. When they miss him, they send messages to his avatar, and they feel closer to him when they do. “There was a lot I didn’t know about my child”. But now that I can read about what he thought about different subjects, I’m getting to know him more. This gives the illusion that he’s here now. I want to repeat that I’m very grateful that I have this”.

2021-09-20: See this recent paper about how truthful the largest NLP models are:

We propose a benchmark to measure whether a language model is truthful in generating answers to questions. The benchmark comprises 817 questions that span 38 categories, including health, law, finance and politics (see Figure 1). We crafted questions that some humans would answer falsely due to a false belief or misconception. To perform well, models must avoid generating false answers learned from imitating human texts. We tested GPT-3, GPT-Neo/GPT-J, GPT-2 and a T5-based model. The best model was truthful on 58% of questions, while human performance was 94%. Models generated many false answers that mimic popular misconceptions and have the potential to deceive humans. The largest models were generally the least truthful (see Figure 2 below). For example, the 6B-parameter GPT-J model was 17% less truthful than its 125M-parameter counterpart. This contrasts with other NLP tasks, where performance improves with model size. However, this result is expected if false answers are learned from the training distribution. We suggest that scaling up models alone is less promising for improving truthfulness than fine-tuning using training objectives other than imitation of text from the web.