A new approach is presented to obtain candidate structures from atomic pair distribution function (PDF) data in a highly automated way. It fetches, from web-based structural databases, all the structures meeting the experimenter's search criteria and performs structure refinements on them without human intervention. It supports both X-ray and neutron PDFs. Tests on various material systems show the effectiveness and robustness of the algorithm in finding the correct atomic crystal structure. It works on crystalline and nanocrystalline materials including complex oxide nanoparticles and nanowires, low-symmetry and locally distorted structures, and complicated doped and magnetic materials. This approach could greatly reduce the traditional structure searching work and enable the possibility of high-throughput real-time auto-analysis PDF experiments in the future.

To mark the 47th anniversary of the Apollo 11 moon-landing mission, the Smithsonian has made available a high-resolution 3-D scan of the command module “Columbia,” […]

The post Apollo 11 Command Module in 3D appeared first on Smithsonian Insider.

This is a short film showing the process of the detail paint work on the conservation of the original U.S.S. Enterprise studio model. The detail […]

The post U.S.S. Enterprise studio model conservation appeared first on Smithsonian Insider.

When Smithsonian Tropical Research Institute paleobotanist Carlos Jaramillo learned that Panama was expanding its canal in 2006 and blasting 100 million tons of rock to […]

The post Using Fossils in Panama to Model Future Climate Change appeared first on Smithsonian Insider.

Mexico is the fourth largest honey producer and fifth largest honey exporter in the world. A Smithsonian researcher and colleagues helped rural farmers in Mexico […]

The post Genetically modified soybean pollen threatens Mexican honey sales appeared first on Smithsonian Insider.

By charting the slopes and crags on animals’ teeth as if they were mountain ranges, scientists at the Smithsonian’s National Museum of Natural History have […]

The post 3D study of teeth in modern mammals opens window to extinct animal diets appeared first on Smithsonian Insider.

Named for Charles Darwin, the only known specimen of a newly discovered beetle, Darwinylus marcosi, died in a sticky battle in a gob of tree […]

The post Beetle and pollen trapped in 105 million-year-old amber reveal fourth major pollination mode in mid-Mesozoic appeared first on Smithsonian Insider.

This article aims to encourage practitioners, young and seasoned, by enhancing their structure-determination toolboxes with a selection of tips and tricks on recognizing and handling aspects of data collection, structure modelling and refinement, and the interpretation of results.

This work presents a technique for extracting the detailed shape of peaks with extended, overlapping tails in an X-ray powder diffraction pattern. The application discussed here concerns crystallite size broadening, though the technique can be applied to spectra of any origin and without regard to how the profiles are to be subsequently analyzed. Historically, the extraction of profile shapes has been difficult due to the complexity of determining the background under the peak, resulting in an offset of the low-frequency components of the Fourier transform of the peak known as the `hook' problem. The use of a carefully considered statistical weighting function in a non-linear least-squares fit, followed by summing the residuals from such a fit with the fit itself, allows one to extract the full shape of an isolated peak, without contributions from either the background or adjacent peaks. The extracted shape, consisting of the fit function recombined with the residuals, is not dependent on any specific shape model. The application of this to analysis of microstructure is performed independently of global parametric models, which would reduce the number of refined parameters; therefore the technique requires high-quality data to produce results of interest. The effectiveness of the technique is demonstrated by extraction of Fourier transforms of peaks from two sets of size-broadened materials with two differing pieces of equipment.

The methods for X-ray crystal orientation are rapidly evolving towards versatility, fewer goniometry measurements, automation, high accuracy and precision. One method that attracts a lot of attention is energy-dispersive X-ray diffraction (EDXRD) which is based on detecting reflections from crystallographic planes in a crystal at fixed angles of a parallel polychromatic X-ray incident beam. In theory, an EDXRD peak can move in a diffraction pattern as a function of a crystallographic plane d-spacing and its orientation relative to a fixed direction in space can change also. This is equivalent to the possibility of measuring the orientation of single crystals. The article provides a modeling for the EDXRD method whose main feature is the nonmoving crystal in the sense of traditional goniometry where the angle measurements of diffracting planes are a must. The article defines the equation of orientation for the method and shows the derivation in great detail. It is shown that the exact solutions of the equations can be obtained using the generalized reduced gradient method, a mathematical subroutine that is implemented in Excel software. The significance and scientific impact of the work are discussed along with the validated tested results.

A new aspherical scattering factor formalism has been implemented in the crystallographic least-squares refinement program SHELXL. The formalism relies on Gaussian functions and can optionally complement the independent atom model to take into account the deformation of electron-density distribution due to chemical bonding and lone pairs. Asphericity contributions were derived from the electron density obtained from quantum-chemical density functional theory computations of suitable model compounds that contain particular chemical environments, as defined by the invariom formalism. Thanks to a new algorithm, invariom assignment for refinement in SHELXL is automated. A suitable parameterization for each chemical environment within the new model was achieved by metaheuristics. Figures of merit, precision and accuracy of crystallographic least-squares refinements improve significantly upon using the new model.

Diffuse scattering is a rich source of information about disorder in crystalline materials, which can be modelled using atomistic techniques such as Monte Carlo and molecular dynamics simulations. Modern X-ray and neutron scattering instruments can rapidly measure large volumes of diffuse-scattering data. Unfortunately, current algorithms for atomistic diffuse-scattering calculations are too slow to model large data sets completely, because the fast Fourier transform (FFT) algorithm has long been considered unsuitable for such calculations [Butler & Welberry (1992). J. Appl. Cryst. 25, 391–399]. Here, a new approach is presented for ultrafast calculation of atomistic diffuse-scattering patterns. It is shown that the FFT can actually be used to perform such calculations rapidly, and that a fast method based on sampling theory can be used to reduce high-frequency noise in the calculations. These algorithms are benchmarked using realistic examples of compositional, magnetic and displacive disorder. They accelerate the calculations by a factor of at least 102, making refinement of atomistic models to large diffuse-scattering volumes practical.

In a Model block, if the instance-specific value of a model argument has an anonymous structure type, an update diagram reports an error when there are multiple bus types that match that anonymous structure type.This bug exists in the following release(s):
R2020a

This bug has a workaround

Interested in Upgrading?

Simulink might produce an incorrect sorted order for a model that meets all of the following conditions:

• The model contains blocks from the SoC Blockset
• The Signal logging option is selected in the model configuration set
• Signals using asynchronous sample time are configured for logging

In small-molecule single-crystal structure determination, we now have at our disposal an inspiring range of fantastic diffractometers with better, brighter sources, and faster, more sensitive detectors. Faster and more powerful computers provide integrated tools and software with impressive graphical user interfaces. Yet these tools can lead to the temptation not to check the work thoroughly and one can too easily overlook tell-tale signs that something might be amiss in a structure determination; validation with checkCIF is not always revealing. This article aims to encourage practitioners, young and seasoned, by enhancing their structure-determination toolboxes with a selection tips and tricks on recognizing and handling aspects that one should constantly be aware of. Topics include a pitfall when setting up data collections, the usefulness of reciprocal lattice layer images, processing twinned data, tips for disorder modelling and the use of restraints, ensuring hydrogen atoms are added to a model correctly, validation beyond checkCIF, and the derivation and interpretation of the final results.

Crystals of the rare earth metal polytelluride LaTe1.82(1), namely, lanthanum telluride (1/1.8), have been grown by molten alkali halide flux reactions and vapour-assisted crystallization with iodine. The two-dimensionally incommensurately modulated crystal structure has been investigated by X-ray diffraction experiments. In contrast to the tetra­gonal average structure with unit-cell dimensions of a = 4.4996 (5) and c = 9.179 (1) Å at 296 (1) K, which was solved and refined in the space group P4/nmm (No. 129), the satellite reflections are not compatible with a tetra­gonal symmetry but enforce a symmetry reduction. Possible space groups have been derived by group–subgroup relationships and by consideration of previous reports on similar rare earth metal polychalcogenide structures. Two structural models in the ortho­rhom­bic superspace group, i.e. Pmmn(α,β,1 over 2)000(−α,β,1 over 2)000 (No. 59.2.51.39) and Pm21n(α,β,1 over 2)000(−α,β,1 over 2)000 (No. 31.2.51.35), with modulation wave vectors q1 = αa* + βb* + 1 over 2c* and q2 = −αa* + βb* + 1 over 2c* [α = 0.272 (1) and β = 0.314 (1)], have been established and evaluated against each other. The modulation describes the distribution of defects in the planar [Te] layer, coupled to a displacive modulation due to the formation of different Te anions. The bonding situation in the planar [Te] layer and the different Te anion species have been investigated by density functional theory (DFT) methods and an electron localizability indicator (ELI-D)-based bonding analysis on three different approximants. The temperature-dependent electrical resistance revealed a semiconducting behaviour with an estimated band gap of 0.17 eV.

The application of groupoids to modular crystal structures is presented.

Structure-mining finds and returns the best-fit structures from structural databases given a measured pair distribution function data set. Using databases and heuristics for automation it has the potential to save experimenters a large amount of time as they explore candidate structures from the literature.

The inversion of X-ray reflectivity to reveal the topography of a one-dimensional interface is evaluated through model calculations.

The emerging science of gene drives has the potential to address environmental and public health challenges, but gene-drive modified organisms are not ready to be released into the environment and require more research in laboratories and highly controlled field trials, says a new report from the National Academies of Sciences, Engineering, and Medicine.

A series of educational modules has been developed by the National Academies of Sciences, Engineering, and Medicine to help students in professional schools – law, public policy, medicine, journalism, and business – understand science and its role in decision making.

For some patients, the ability to participate in a clinical trial from the comfort of one’s home is becoming a reality.

US President Barack Obama and Republican Presidential nominee Mitt Romney debate on October 16, 2012 at Hofstra University in Hempstead, New York. Undecided voters asked questions during a town hall format.; Credit: STAN HONDA/AFP/Getty Images

There continue to be questions about how moderators approach Presidential debates and about whether the extra time President Obama has received in the first two debates indicates moderator bias in his favor. 

I had chalked up the concerns to Republican hyper-partisanship, such as we saw with many Democrats criticizing Jim Lehrer for his moderating — as though Obama would’ve won the first debate if only Lehrer had asserted himself more.   However, even CNN has been doing significant follow-up on its own Candy Crowley’s performance in debate number two. 

Maybe it’s not just hardcore GOP loyalists who are questioning Crowley’s decision-making on when to cut in and when to allow the candidates to take more time. I thought she did pretty well, but there are plenty of critics.

As someone who has moderated hundreds of debates, I thought I’d share my thoughts on what we’ve seen so far in this election. Though I’ve never moderated a Presidential debate, with its incredible level of attention, concern about rules, and demands by campaigns, there are certain fundamentals regardless of the office or issue at stake.

Time Doesn't Matter...Too Much
First, as strange as this may sound, the time taken by each candidate has little to do with who has an advantage.   Yes, it’s always possible for a candidate to use another minute to fire off the defining line of the night. However, the well-practiced zingers or essential policy explainers are not left to the end of a candidate’s statement, as the clock is running out. 

I’m sure Mitt Romney wasn’t thinking after the last debate, “If only I would’ve had that extra 90-seconds, and Obama hadn’t gotten 90 more than he deserved.”  Both men front-loaded their major talking points and were going to get them in. Neither man could legitimately say he didn’t have a chance to make his strongest points. At some point, a time advantage could make a difference in who wins or loses, but an extra 90-seconds in a debate longer than 90-minutes isn’t going to do it.

Serving The Audience
As a moderator, you also have to think about what best serves your audience. I never guarantee candidates equal time, as it’s my job to serve the listeners, not their campaigns. I strive to get close to equal time, but can’t make any guarantee. Some speakers get to the point succinctly and have their points well put together. Others are messier in their arguments and eat up time just building up any head of steam. 

If the moderator holds to a strict time limit, you run the risk of frustrating listeners by cutting off the rambler just as the candidate is getting to the point. There are methods a moderator can use to help guide the speaker toward being more succinct, but there’s no guarantee the person will be able to comply.

Isn’t this inherently unfair to the succinct speaker? No. The purpose of the debate is to allow the ideas to compete.  It’s not a boxing match that’s about landing punches in a given time. The succinct debater has a big advantage, regardless of how much time the candidate has. That’s why Mitt Romney’s victory in the first debate was so lopsided — he won on the conciseness and clarity of his answers, coupled with Obama’s inability to get to his central points.  Obviously, there are those who thought Obama’s arguments were still more compelling than Romney’s, and that Romney lacked essential details.  However, for most viewers of the first debate, it was stylistically no contest.

Equal Time Is Not A Guarantee
When candidates are allowed to talk to each other directly, it’s very difficult to assure equal time. Even CNN’s clock that registers elapsed time for each candidate is subject to squishiness. Unless a debate is extremely formal, with carefully controlled time limits and a ban on candidates following-up with each other, you’re only going to have an approximation of time balance. I thought Crowley did pretty well to land the second debate with the balance she did. I’m not sure I could get it that close for a debate of that length. She had the added challenge of trying to determine when to cut in on President Obama’s lengthier answers. Also, Romney’s speaking rhythm allows more space for interruption. It’s tougher to break in on Obama.

Moderating Is A Balancing Act
Moderators are always trying to balance a need to move on to the next topic with allowing a candidate to answer an opponent’s charge. Sometimes, you open that door for a candidate, only to regret it later when the politician starts into a monologue, instead of confining the response to the previous challenge. Sometimes moderators, having gotten burned, will become less tolerant of such expansive rebuttals, as the debate goes on. Moderators are always juggling competing goals, and it’s a difficult job (at least for me).

Unfortunately, there are those who think debate moderators attempt to influence the outcome of the debate and the performances of the candidates. Maybe I’m naïve, but I can’t imagine any journalist who’s worked hard enough to get to the position of Presidential debate moderator subordinating his or her career in an effort to getting someone elected. Mainstream political journalism is like national sports reporting. You really don’t care who wins the Super Bowl, you want great story lines to explore with your audience. Yes, sports reporters have affinities for the hometown teams of their youth, but that can’t compete with the professional goal of covering great stories. 

Yes, most journalists in mainstream media probably have a stronger cultural and political affinity for Obama, as he’s more like them. However, it doesn’t mean a journalist is going to sacrifice the better story to intentionally provide a benefit to the President.

This content is from Southern California Public Radio. View the original story at SCPR.org.

A cleaning crew disinfects a New York City subway train on May 4, 2020 in New York City. ; Credit: Stephanie Keith/Getty Images

As of Monday afternoon, L.A. County has at least 1,260 deaths and 26,238 confirmed cases of coronavirus. The United States has more than a million cases of the virus with more than 67,000 deaths. Meanwhile, new models put together by FEMA project that we could see up to 200,000 new cases a day by the end of the month, according to the New York Times. 

The L.A. Times reports that scientists have discovered a new strain of the deadly coronavirus that is even more contagious. The study finds that the new strain first appeared in February in Europe and has been the dominant strain across the world since mid-March. Plus, some COVID-19 patients are experiencing issues with blood clotting even after respiratory issues have died down. Today on AirTalk, we get the latest with an infectious disease specialist who will take your questions. Call 866-893-5722 to join the conversation. 

With files from LAist. Read the full story here.

Guest:

Dean Blumberg, M.D., professor of medicine and chief of Pediatric Infectious Diseases at UC Davis Children’s Hospital

This content is from Southern California Public Radio. View the original story at SCPR.org.

Image modeling for biomedical organs

Will Davidson and his Minecraft creation, modeled off the Santa Cruz Mission; Credit: Steve Henn

Minecraft is a deceptively simple video game. You're dropped into a virtual world, and you get to build things. It's like a digital Lego set, but with infinite pieces.

Its simplicity makes it a big hit with kids, like 10-year old Will Davidson. Last year, Will built a Spanish mission for a school report. He modeled his off the Santa Cruz Mission. "I made a chapel over here," Davidson says. "I also have a bell tower."

After he turned in his report, he added a few things. Like skeleton archers. "And zombies ... and exploding things, and spiders, that try to kill you," he said.

Minecraft is popular with kids because they're free to create almost anything, says Ramin Shokrizade, a game designer.

Also, kids aren't manipulated into clicking buttons to buy add-ons within the game. In other games, designers give players a special power for free at first, then take it away and offer it back at a price.

Zynga, the creator of Farmville, calls this fun pain, according to Shokrizade. "That's the idea that, if you make the consumer uncomfortable enough, and then tell them that for money we'll make you less uncomfortable, then [they] will give us money," he says.

Kids, Shokrizade says, are especially susceptible to this — and Minecraft has a loyal following, in part, because it doesn't do it.

Susan Linn, from the Campaign for a Commercial-Free Childhood, agrees. She says a big reason she likes Minecraft is because after you purchase the game upfront, that's it.

"Parents don't have to worry that their kids are going to be targeted for more marketing," Linn says. "How forward-thinking!"

But Linn is worried. Microsoft bought Mojang, the company that created Minecraft, on Monday for $2.5 billion, and she says that any time a large company spends billions to acquire a smaller company, executives are bound start looking for new ways to get even more money out of it.

Building Information Modelling (BIM) can enhance the design of a building, reduce costs and save energy. However, little research has been carried out on its impact on sustainable practices. A US survey illustrates that many practitioners do not see sustainability as a primary application, suggesting that more effort is needed to encourage the integration of ‘green’ design and construction into BIM.

Integrated environmental modelling (IEM) is an organised approach to streamlining the movement of scientific information from its research sources to its application in problem solving, according to a study that envisions a global-scale IEM community. The researchers present a roadmap for the future of IEM, describing issues that could be addressed to develop its potential even further, such as how best to integrate diverse stakeholder perspectives and appropriate guidelines for ‘problem statements’.

An international team of scientists has described a rare fossil site that is believed to be among the earliest evidence of different fish species using a common nursery -- much like ones utilized by some fish today.

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Effective flood-risk management requires accurate risk-analysis models. Conventional analysis approaches, however, are based on the evaluation of spatially homogenous scenarios, which do not account for variation in flooding across a river reach/ region. Since flood events are often spatially heterogeneous (i.e. unevenly distributed), this paves the way for error. Now, scientists have developed a novel framework for risk analysis that accounts for their heterogeneity, and successfully demonstrated the accuracy of the approach by applying it in a proof-of-concept exercise in Vorarlberg, Austria. By facilitating improved prediction and quantification of flood events, this model is likely to inform future flood-risk management and related decision-making.

Estonian research has identified land use practices and agrochemical use as the main pressures that are causing a decline in pollinating insects in Europe, such as bees and butterflies. It calls for increased funds for agri-environment measures from the Common Agricultural Policy (CAP) to help tackle pollinator loss.

Most modern societies depend on fossil fuels (oil, gas and coal) as sources of energy for development and growth. Switching to renewable energy sources, such as photovoltaic (PV) systems, is necessary for sustainable development in the future. A new study suggests that it is currently much more efficient to use fossil fuels to develop PV power plants than to combust the same amount of fossil fuels in conventional thermal power plants: thus the sooner PV systems are developed, the sooner society will reduce its reliance on fossil fuels.