In lab “taste tests,” this crayfish native to the Ohio River valley displayed no preference for protein or plants, even after weeks on an exclusive diet of one or the other, according to a new UC study. The crayfish has more cellulose-digesting bacteria when its diet is restricted to plants.

“They tend to be more aggressive than native crayfish,” said Mark Tran, a UC biologist who led the project. “They have relatively large claws compared to their body size. They will either force the other crayfish out or outcompete them for food.”

Tran and his colleagues presented findings from two studies at the Society for Integrative and Comparative Biology conference in January.

The rusty crayfish looks like a little bronze lobster with its thick body and formidable pincers. It is native to creeks and ponds in Ohio, northern Kentucky and Indiana.

Wildlife managers suspect fishermen who catch rusty crayfish for bait introduced them into streams as far away as Oregon and Canada, where they are outcompeting native crayfish and destroying fish nurseries with their ravenous appetites. According to the Minnesota Sea Grant, the hungry crayfish feed on aquatic vegetation along with invertebrates that baby fish eat.

“The irony is that bass fishermen are responsible for releasing them into waters where they end up reducing the native sportfish population,” said Tran, an assistant professor of biology for UC Blue Ash.

In Canada, Ontario took the extraordinary step of outlawing the transport of any crayfish anywhere in the province to try to stop the rusty crayfish from spreading. Fishermen there have to catch crayfish for bait in the same waters they fish.

“They tend to be opportunistic,” Tran said. “They will actively kill things and eat them. But in the streams we studied, they tend to be more omnivorous. They eat a lot of plant material and supplement it with dead fish or eggs they find.”

For the project, UC obtained a collection permit from the Great Parks of Hamilton County. Students collected 40 female crayfish from a suburban Cincinnati creek. Half were fed a plant-based diet; the others a meat-based diet.

After a month, the crayfish with the vegetarian diet had more cellulose-digesting bacteria compared to the meat-eating crayfish.

“Plants can be hard to digest because of their cell walls,” Tran said. “To get nutrients from the plants, they need bacteria in their gut that can digest that cell wall. Rusty crayfish have a digestive system that is good at breaking down the plant’s cell walls.”

After a month on the strict diet, the crayfish were presented a choice of protein- or plant-based food through plastic tubes in an experimental arena. During a second trial, students offered each crayfish the two food choices in its individual habitat container.

Surprisingly, researchers found variety is not the spice of life for crayfish. The crayfish expressed no statistically significant preference for one food over another in either experiment despite their month-long restricted diet.

The findings support what is known about rusty crayfish — they are generalists that will eat almost anything, which helps to explain why they are so successful colonizing new habitats where they are introduced as invasive species.

“Unfortunately, rusty crayfish are well established in Ontario and cannot be eradicated,” said Jolanta Kowalski, a spokeswoman for the Ontario Ministry of Natural Resources and Forestry. “The introduction of the species occurred in the 1960s and they have become well established.”

This was the third year of UC’s crayfish project, which was conceived to give undergraduate students lab experience, associate professor Keen Wilson said.

“The point is to give students an introduction to a variety of biology specialties,” Wilson said.

“For example, I don’t go outside. I know that about myself, so I stick to lab work,” he said. “But you might not know that about yourself as a freshman. So you go out in the field and collect crayfish and say, ‘I’ll never do that again as long as I live.’ But you might love working in the lab or looking at the microbiology plates.”

Now, a team of scientists from Purdue University and other research institutions around the world have come together to better understand the growing number of worldwide patented innovations available for gene therapy treatment. They specifically focus on nonviral methods, which use synthetic or natural compounds or physical forces to deliver materials generally less toxic than their viral counterparts into the therapy treatments.

“The possibility of using nonviral vectors for gene therapy represents one of the most interesting and intriguing fields of gene therapy research,” said Marxa Figueiredo, an associate professor of basic medical sciences in Purdue’s College of Veterinary Medicine, who helped lead the research team and works with the Purdue Research Foundation Office of Technology Commercialization to patent her technologies related to health. “This is an innovative method for identifying the technological routes used by universities and companies across the world and uncovering emerging trends for different gene therapy sectors.”

The scientists used big data, patent and clinical data mining to identify technological trends for the gene therapy field. The team’s work is presented in the Feb. 7 edition of Nature Biotechnology. They envision that their analysis will help guide future developments for gene therapy.

This work brought together investigators from across the globe in a joint effort to use new databases and methods to better understand the trends of the gene therapy field in respect to nonviral vectors. Dimas Covas, coordinator of the Center for Cell-based Therapy, affiliated with the University of São Paulo in Brazil, lent his extensive experience in cell therapy. Aglaia Athanassiadou, Virginia Picanço-Castro and Figueiredo contributed their extensive experience on nonviral vectors for gene therapy. Cristiano Pereira and Geciane Porto brought their expertise in economics and business administration to the analyses. Each contribution was fundamental to achieving a new way to identify technological trends in this field.

“This work brought together investigators from very diverse disciplines to create a different perspective of the gene therapy field,” Figueiredo said. “Our groups continue to work individually or in collaboration to generate and patent new vectors to help fill the needs of this re-emerging field of nonviral gene therapy.”

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Materials provided by Purdue University. Original written by Chris Adam. Note: Content may be edited for style and length.

One of the most difficult aspects of learning a foreign language has to do with pronunciation. Learners are typically prone to specific sets of errors, which differ depending on the learners first language. For instance, Germans typically have trouble articulating the initial ‘th’ in

English, as evidenced by the classical expression ‘Senk ju vor träwelling’ familiar to passengers on German railways. Conversely, native speakers of English tend to have difficulty with the German ‘ü’, which they tend to pronounce as ‘u’. Many people laugh at these mistakes in pronunciation, even though they make the same mistakes themselves. But this reaction in itself points to a paradox: It demonstrates that learners register errors when made by others. Nevertheless, the majority of language learners finds it virtually impossible to eliminate these typical errors even after years of practice. A study carried out by LMU linguists Eva Reinisch and Nikola Eger, in collaboration with Holger Mitterer from the University of Malta, has now uncovered one reason for this paradox. “Learners have a tendency to overestimate the quality of their own pronunciation,” says Reinisch. “As a rule, they believe that their English is better than that spoken by their fellow students at language schools, although they make the same set of errors.” This exaggerated assessment of one’s own ability is an important factor that helps explaining why it is so difficult to learn the sounds of a foreign language.

In the study, the researchers asked 24 female German learners of English to read out 60 short sentences, such as “The family bought a house,” “The jug is on the shelf,” and “They heard a funny noise.” Several weeks later, the same learners were invited back to the lab and asked to listen to recordings of four learners — three others and themselves. Specifically, they were asked to grade the pronunciation of each sentence. In order to ensure that participants would not recognize their own productions, the recordings were manipulated in such a way that the female speakers sounded like male speakers. “This element of the experimental design is crucial. It was essential that none of listeners would be aware that their own productions were included in the test sample; otherwise their assessments couldn’t be taken as unbiased,” says Holger Mitterer. The results of this test were unambiguous. In all cases, the listeners rated their own pronunciation as better than others did, even though they were unable to recognize that it was their own recording. “We were surprised that the experiment so clearly pointed to the significance of overestimation of one’s own abilities in this context,” says Reinisch.

There are several possible explanations for these findings. Previous research has shown that familiar accents are easier to understand than accents that are less familiar. “One is best acquainted with the sound of one’s own voice, and has no difficulty understanding it,” says Reinisch, who is at LMU’s Institute of Phonetics and Language Processing. “Perhaps this familiarity leads us to regard our pronunciation as being better than it actually is.” Another possible contributory factor is what is known as the ‘mere exposure’ effect. This term refers to the fact that we tend to rate things with which we are more familiar — such as the sound of our own voice — as more congenial.

The results of the study underline the importance of external feedback in language courses, because it increases the learners; awareness of deficits in language production and comprehension. “As long as we believe that we are already pretty good, we are not going to put in more effort to improve,” Reinisch points out. A lack of feedback increases the risk of what researchers refer to as ‘fossilization’. Leaners feel that they have already mastered the unfamiliar articulation patterns in the new language, although that is in fact not the case. They therefore see no reason why they should invest more time in improving their pronunciation. The authors of the new study are not likely to fall into this sort of error. They are already considering ways to improve the situation with the aid of apps that generate the necessary external feedback — irrespective of how users rate their own performance.

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The system uses multiple layers of flat solar evaporators and condensers, lined up in a vertical array and topped with transparent aerogel insulation. It is described in a paper appearing today in the journal Energy and Environmental Science, authored by MIT doctoral students Lenan Zhang and Lin Zhao, postdoc Zhenyuan Xu, professor of mechanical engineering and department head Evelyn Wang, and eight others at MIT and at Shanghai Jiao Tong University in China.

The key to the system’s efficiency lies in the way it uses each of the multiple stages to desalinate the water. At each stage, heat released by the previous stage is harnessed instead of wasted. In this way, the team’s demonstration device can achieve an overall efficiency of 385 percent in converting the energy of sunlight into the energy of water evaporation.

The device is essentially a multilayer solar still, with a set of evaporating and condensing components like those used to distill liquor. It uses flat panels to absorb heat and then transfer that heat to a layer of water so that it begins to evaporate. The vapor then condenses on the next panel. That water gets collected, while the heat from the vapor condensation gets passed to the next layer.

Whenever vapor condenses on a surface, it releases heat; in typical condenser systems, that heat is simply lost to the environment. But in this multilayer evaporator the released heat flows to the next evaporating layer, recycling the solar heat and boosting the overall efficiency.

“When you condense water, you release energy as heat,” Wang says. “If you have more than one stage, you can take advantage of that heat.”

Adding more layers increases the conversion efficiency for producing potable water, but each layer also adds cost and bulk to the system. The team settled on a 10-stage system for their proof-of-concept device, which was tested on an MIT building rooftop. The system delivered pure water that exceeded city drinking water standards, at a rate of 5.78 liters per square meter (about 1.52 gallons per 11 square feet) of solar collecting area. This is more than two times as much as the record amount previously produced by any such passive solar-powered desalination system, Wang says.

Theoretically, with more desalination stages and further optimization, such systems could reach overall efficiency levels as high as 700 or 800 percent, Zhang says.

Unlike some desalination systems, there is no accumulation of salt or concentrated brines to be disposed of. In a free-floating configuration, any salt that accumulates during the day would simply be carried back out at night through the wicking material and back into the seawater, according to the researchers.

Their demonstration unit was built mostly from inexpensive, readily available materials such as a commercial black solar absorber and paper towels for a capillary wick to carry the water into contact with the solar absorber. In most other attempts to make passive solar desalination systems, the solar absorber material and the wicking material have been a single component, which requires specialized and expensive materials, Wang says. “We’ve been able to decouple these two.”

The most expensive component of the prototype is a layer of transparent aerogel used as an insulator at the top of the stack, but the team suggests other less expensive insulators could be used as an alternative. (The aerogel itself is made from dirt-cheap silica but requires specialized drying equipment for its manufacture.)

Wang emphasizes that the team’s key contribution is a framework for understanding how to optimize such multistage passive systems, which they call thermally localized multistage desalination. The formulas they developed could likely be applied to a variety of materials and device architectures, allowing for further optimization of systems based on different scales of operation or local conditions and materials.

One possible configuration would be floating panels on a body of saltwater such as an impoundment pond. These could constantly and passively deliver fresh water through pipes to the shore, as long as the sun shines each day. Other systems could be designed to serve a single household, perhaps using a flat panel on a large shallow tank of seawater that is pumped or carried in. The team estimates that a system with a roughly 1-square-meter solar collecting area could meet the daily drinking water needs of one person. In production, they think a system built to serve the needs of a family might be built for around $100.

The researchers plan further experiments to continue to optimize the choice of materials and configurations, and to test the durability of the system under realistic conditions. They also will work on translating the design of their lab-scale device into a something that would be suitable for use by consumers. The hope is that it could ultimately play a role in alleviating water scarcity in parts of the developing world where reliable electricity is scarce but seawater and sunlight are abundant.

The research team included Bangjun Li, Chenxi Wang and Ruzhu Wang at the Shanghai Jiao Tong University, and Bikram Bhatia, Kyle Wilke, Youngsup Song, Omar Labban, and John Lienhard, who is the Abdul Latif Jameel Professor of Water at MIT. The research was supported by the National Natural Science Foundation of China, the Singapore-MIT Alliance for Research and Technology, and the MIT Tata Center for Technology and Design.

Cosmologists nowadays assume that matter was not distributed entirely evenly after the Big Bang. The denser places attracted more and more matter from their surroundings due to their stronger gravitational forces. Over the course of several billion years, these accumulations of gas eventually formed the galaxies we see today.

An important ingredient of this theory is the so-called dark matter. On the one hand, it is said to be responsible for the initial uneven distribution that led to the agglomeration of the gas clouds. It also explains some puzzling observations. For instance, stars in rotating galaxies often move so fast that they should actually be ejected. It appears that there is an additional source of gravity in the galaxies that prevents this — a kind of “star putty” that cannot be seen with telescopes: dark matter.

However, there is still no direct proof of its existence. “Perhaps the gravitational forces themselves simply behave differently than previously thought,” explains Prof. Dr. Pavel Kroupa from the Helmholtz Institute for Radiation and Nuclear Physics at the University of Bonn and the Astronomical Institute of Charles University in Prague. This theory bears the abbreviation MOND (MOdified Newtonian Dynamics); it was discovered by the Israeli physicist Prof. Dr. Mordehai Milgrom. According to the theory, the attraction between two masses obeys Newton’s laws only up to a certain point. Under very low accelerations, as is the case in galaxies, it becomes considerably stronger. This is why galaxies do not break apart as a result of their rotational speed.

Results close to reality

“In cooperation with Dr. Benoit Famaey in Strasbourg, we have now simulated for the first time whether galaxies would form in a MOND universe and if so, which ones,” says Kroupa’s doctoral student Nils Wittenburg. To do this he used a computer program for complex gravitational calculations which was developed in Kroupa’s group. Because with MOND, the attraction of a body depends not only on its own mass, but also on whether other objects are in its vicinity.

The scientists then used this software to simulate the formation of stars and galaxies, starting from a gas cloud several hundred thousand years after the Big Bang. “In many aspects, our results are remarkably close to what we actually observe with telescopes,” explains Kroupa. For instance, the distribution and velocity of the stars in the computer-generated galaxies follow the same pattern that can be seen in the night sky. “Furthermore, our simulation resulted mostly in the formation of rotating disk galaxies like the Milky Way and almost all other large galaxies we know,” says the scientist. “Dark matter simulations, on the other hand, predominantly create galaxies without distinct matter disks — a discrepancy to the observations that is difficult to explain.”

Calculations based on the existence of dark matter are also very sensitive to changes in certain parameters, such as the frequency of supernovae and their effect on the distribution of matter in galaxies. In the MOND simulation, however, these factors hardly played a role.

Yet the recently published results from Bonn, Prague and Strasbourg do not correspond to reality in all points. “Our simulation is only a first step,” emphasizes Kroupa. For example, the scientists have so far only made very simple assumptions about the original distribution of matter and the conditions in the young universe. “We now have to repeat the calculations and include more complex influencing factors. Then we will see if the MOND theory actually explains reality.”

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