are small zooplankton found in freshwater inland lakes and are thought to switch their mode of reproduction from asexual to sexual in response to extreme temperatures (Mitchell 1999). Lakes containing have an average summer surface temperature of 20°C (Harper 1995) but may increase by more than 15% when expose to warm water effluent from power plants, paper mills, and chemical industry (Baker et al. 2000). Could an increase in lake temperature caused by industrial thermal pollution affect the survivorship and reproduction of ?
The sex of is mediated by the environment rather than genetics. Under optimal environmental conditions, populations consist of asexually reproducing females. When the environment shifts may be queued to reproduce sexually resulting in the production of male offspring and females carrying haploid eggs in sacs called ephippia (Mitchell 1999).
The purpose of this laboratory study is to examine the effects of increased water temperature on survivorship and reproduction. This study will help us characterize the magnitude of environmental change required to induce the onset of the sexual life cycle in . Because are known to be a sensitive environmental indicator species (Baker et al. 2000) and share similar structural and physiological features with many aquatic species, they serve as a good model for examining the effects of increasing water temperature on reproduction in a variety of aquatic invertebrates.
We hypothesized that populations reared in water temperatures ranging from 24-26 °C would have lower survivorship, higher male/female ratio among the offspring, and more female offspring carrying ephippia as compared with grown in water temperatures of 20-22°C. To test this hypothesis we reared populations in tanks containing water at either 24 +/- 2°C or 20 +/- 2°C. Over 10 days, we monitored survivorship, determined the sex of the offspring, and counted the number of female offspring containing ephippia.
Comments:
Background information
· Opening paragraph provides good focus immediately. The study organism, gender switching response, and temperature influence are mentioned in the first sentence. Although it does a good job documenting average lake water temperature and changes due to industrial run-off, it fails to make an argument that the 15% increase in lake temperature could be considered “extreme” temperature change.
· The study question is nicely embedded within relevant, well-cited background information. Alternatively, it could be stated as the first sentence in the introduction, or after all background information has been discussed before the hypothesis.
Rationale
· Good. Well-defined purpose for study; to examine the degree of environmental change necessary to induce the Daphnia sexual life
cycle.
How will introductions be evaluated? The following is part of the rubric we will be using to evaluate your papers.
0 = inadequate (C, D or F) | 1 = adequate (BC) | 2 = good (B) | 3 = very good (AB) | 4 = excellent (A) | |
Introduction BIG PICTURE: Did the Intro convey why experiment was performed and what it was designed to test?
| Introduction provides little to no relevant information. (This often results in a hypothesis that “comes out of nowhere.”) | Many key components are very weak or missing; those stated are unclear and/or are not stated concisely. Weak/missing components make it difficult to follow the rest of the paper. e.g., background information is not focused on a specific question and minimal biological rationale is presented such that hypothesis isn’t entirely logical
| Covers most key components but could be done much more logically, clearly, and/or concisely. e.g., biological rationale not fully developed but still supports hypothesis. Remaining components are done reasonably well, though there is still room for improvement. | Concisely & clearly covers all but one key component (w/ exception of rationale; see left) clearly covers all key components but could be a little more concise and/or clear. e.g., has done a reasonably nice job with the Intro but fails to state the approach OR has done a nice job with Intro but has also included some irrelevant background information
| Clearly, concisely, & logically presents all key components: relevant & correctly cited background information, question, biological rationale, hypothesis, approach. |
How old your research sources can be, using the publication date or date of creation as the defining criteria, is either stated in your assignment rubric or depends on your field of study or academic discipline. If it’s a requirement for your assignment, look for words like “sources must be published in the last 10 years” or words to that effect that specify the publication date or range required. If the currency of sources is not a requirement of your assignment, think about the course involved and what an appropriate age might be.
How fast-changing is the field of study?
Sources for a history paper might, by their very nature, be older if they are diaries, personal letters, or other documents created long ago and used as primary sources. Sources used for research in the sciences (health care, nursing, engineering), business and finance, and education and other social science fields require more “cutting edge” research, as these fields change quickly with the acquisition of new knowledge and the need to share it rapidly with practitioners in those fields.
A good rule of thumb is to use sources published in the past 10 years for research in the arts, humanities, literature, history, etc.
For faster-paced fields, sources published in the past 2-3 years is a good benchmark since these sources are more current and reflect the newest discoveries, theories, processes, or best practices.
Use the library’s Multi-Search search results page to limit your sources to those published within a date range you specify. Use the Publication Date custom setting seen on the left side of the search results page:
For further assistance with this or other search techniques, contact the Shapiro Library email at [email protected] or use our 24/7 chat service.
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Maureen a. carey.
Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America
William a. petri, jr, introduction.
“There is no problem that a library card can't solve” according to author Eleanor Brown [ 1 ]. This advice is sound, probably for both life and science, but even the best tool (like the library) is most effective when accompanied by instructions and a basic understanding of how and when to use it.
For many budding scientists, the first day in a new lab setting often involves a stack of papers, an email full of links to pertinent articles, or some promise of a richer understanding so long as one reads enough of the scientific literature. However, the purpose and approach to reading a scientific article is unlike that of reading a news story, novel, or even a textbook and can initially seem unapproachable. Having good habits for reading scientific literature is key to setting oneself up for success, identifying new research questions, and filling in the gaps in one’s current understanding; developing these good habits is the first crucial step.
Advice typically centers around two main tips: read actively and read often. However, active reading, or reading with an intent to understand, is both a learned skill and a level of effort. Although there is no one best way to do this, we present 10 simple rules, relevant to novices and seasoned scientists alike, to teach our strategy for active reading based on our experience as readers and as mentors of undergraduate and graduate researchers, medical students, fellows, and early career faculty. Rules 1–5 are big picture recommendations. Rules 6–8 relate to philosophy of reading. Rules 9–10 guide the “now what?” questions one should ask after reading and how to integrate what was learned into one’s own science.
What you want to get out of an article should influence your approach to reading it. Table 1 includes a handful of example intentions and how you might prioritize different parts of the same article differently based on your goals as a reader.
Examples | Intention | Priorities |
---|---|---|
1 | You are new to reading scientific papers. | For each panel of each figure, focus particularly on the questions outlined in Rule 3. |
2 | You are entering a new field and want to learn what is important in that field. | Focus on the beginning (motivation presented in the introduction) and the end (next steps presented in the conclusion). |
3 | You receive automated alerts to notify you of the latest publication from a particular author whose work inspires you; you are hoping to work with them for the next phase of your research career and want to know what they are involved in. | Skim the entire work, thinking about how it fits into the author’s broader publication history. |
4 | You receive automated alerts to notify you of the latest publication containing a set of keywords because you want to be aware of new ways a technique is being applied or the new developments in a particular topic or research area. | Focus on what was done in the methods and the motivation for the approach taken; this is often presented in the introduction. |
5 | You were asked to review an article prior to publication to evaluate the quality of work or to present in a journal club. | Same as example 1. Also, do the data support the interpretations? What alternative explanations exist? Are the data presented in a logical way so that many researchers would be able to understand? If the research is about a controversial topic, do the author(s) appropriately present the conflict and avoid letting their own biases influence the interpretation? |
1 Yay! Welcome!
2 A journal club is when a group of scientists get together to discuss a paper. Usually one person leads the discussion and presents all of the data. The group discusses their own interpretations and the authors’ interpretation.
In written communication, the reader and the writer are equally important. Both influence the final outcome: in this case, your scientific understanding! After identifying your goal, think about the author’s goal for sharing this project. This will help you interpret the data and understand the author’s interpretation of the data. However, this requires some understanding of who the author(s) are (e.g., what are their scientific interests?), the scientific field in which they work (e.g., what techniques are available in this field?), and how this paper fits into the author’s research (e.g., is this work building on an author’s longstanding project or controversial idea?). This information may be hard to glean without experience and a history of reading. But don’t let this be a discouragement to starting the process; it is by the act of reading that this experience is gained!
A good step toward understanding the goal of the author(s) is to ask yourself: What kind of article is this? Journals publish different types of articles, including methods, review, commentary, resources, and research articles as well as other types that are specific to a particular journal or groups of journals. These article types have different formatting requirements and expectations for content. Knowing the article type will help guide your evaluation of the information presented. Is the article a methods paper, presenting a new technique? Is the article a review article, intended to summarize a field or problem? Is it a commentary, intended to take a stand on a controversy or give a big picture perspective on a problem? Is it a resource article, presenting a new tool or data set for others to use? Is it a research article, written to present new data and the authors’ interpretation of those data? The type of paper, and its intended purpose, will get you on your way to understanding the author’s goal.
When reading, ask yourself: (1) What do the author(s) want to know (motivation)? (2) What did they do (approach/methods)? (3) Why was it done that way (context within the field)? (4) What do the results show (figures and data tables)? (5) How did the author(s) interpret the results (interpretation/discussion)? (6) What should be done next? (Regarding this last question, the author(s) may provide some suggestions in the discussion, but the key is to ask yourself what you think should come next.)
Each of these questions can and should be asked about the complete work as well as each table, figure, or experiment within the paper. Early on, it can take a long time to read one article front to back, and this can be intimidating. Break down your understanding of each section of the work with these questions to make the effort more manageable.
Scientists write original research papers primarily to present new data that may change or reinforce the collective knowledge of a field. Therefore, the most important parts of this type of scientific paper are the data. Some people like to scrutinize the figures and tables (including legends) before reading any of the “main text”: because all of the important information should be obtained through the data. Others prefer to read through the results section while sequentially examining the figures and tables as they are addressed in the text. There is no correct or incorrect approach: Try both to see what works best for you. The key is making sure that one understands the presented data and how it was obtained.
For each figure, work to understand each x- and y-axes, color scheme, statistical approach (if one was used), and why the particular plotting approach was used. For each table, identify what experimental groups and variables are presented. Identify what is shown and how the data were collected. This is typically summarized in the legend or caption but often requires digging deeper into the methods: Do not be afraid to refer back to the methods section frequently to ensure a full understanding of how the presented data were obtained. Again, ask the questions in Rule 3 for each figure or panel and conclude with articulating the “take home” message.
Just like the overall intent of the article (discussed in Rule 2), the intent of each section within a research article can guide your interpretation. Some sections are intended to be written as objective descriptions of the data (i.e., the Results section), whereas other sections are intended to present the author’s interpretation of the data. Remember though that even “objective” sections are written by and, therefore, influenced by the authors interpretations. Check out Table 2 to understand the intent of each section of a research article. When reading a specific paper, you can also refer to the journal’s website to understand the formatting intentions. The “For Authors” section of a website will have some nitty gritty information that is less relevant for the reader (like word counts) but will also summarize what the journal editors expect in each section. This will help to familiarize you with the goal of each article section.
Section | Content |
---|---|
Title | The “take home” message of the entire project, according to the authors. |
Author list | These people made significant scientific contributions to the project. Fields differ in the standard practice for ordering authors. For example, as a general rule for biomedical sciences, the first author led the project’s implementation, and the last author was the primary supervisor to the project. |
Abstract | A brief overview of the research question, approach, results, and interpretation. This is the road map or elevator pitch for an article. |
Introduction | Several paragraphs (or less) to present the research question and why it is important. A newcomer to the field should get a crash course in the field from this section. |
Methods | What was done? How was it done? Ideally, one should be able to recreate a project by reading the methods. In reality, the methods are often overly condensed. Sometimes greater detail is provided within a “Supplemental” section available online (see below). |
Results | What was found? Paragraphs often begin with a statement like this: “To do X, we used approach Y to measure Z.” The results should be objective observations. |
Figures, tables, legends, and captions | The data are presented in figures and tables. Legends and captions provide necessary information like abbreviations, summaries of methods, and clarifications. |
Discussion | What do the results mean and how do they relate to previous findings in the literature? This is the perspective of the author(s) on the results and their ideas on what might be appropriate next steps. Often it may describe some (often not all!) strengths and limitations of the study: Pay attention to this self-reflection of the author(s) and consider whether you agree or would add to their ideas. |
Conclusion | A brief summary of the implications of the results. |
References | A list of previously published papers, datasets, or databases that were essential for the implementation of this project or interpretation of data. This section may be a valuable resource listing important papers within the field that are worth reading as well. |
Supplemental material | Any additional methods, results, or information necessary to support the results or interpretations presented in the discussion. |
Supplemental data | Essential datasets that are too large or cumbersome to include in the paper. Especially for papers that include “big data” (like sequencing or modeling results), this is often where the real, raw data is presented. |
Research articles typically contain each of these sections, although sometimes the “results” and “discussion” sections (or “discussion” and “conclusion” sections) are merged into one section. Additional sections may be included, based on request of the journal or the author(s). Keep in mind: If it was included, someone thought it was important for you to read.
Published papers are not truths etched in stone. Published papers in high impact journals are not truths etched in stone. Published papers by bigwigs in the field are not truths etched in stone. Published papers that seem to agree with your own hypothesis or data are not etched in stone. Published papers that seem to refute your hypothesis or data are not etched in stone.
Science is a never-ending work in progress, and it is essential that the reader pushes back against the author’s interpretation to test the strength of their conclusions. Everyone has their own perspective and may interpret the same data in different ways. Mistakes are sometimes published, but more often these apparent errors are due to other factors such as limitations of a methodology and other limits to generalizability (selection bias, unaddressed, or unappreciated confounders). When reading a paper, it is important to consider if these factors are pertinent.
Critical thinking is a tough skill to learn but ultimately boils down to evaluating data while minimizing biases. Ask yourself: Are there other, equally likely, explanations for what is observed? In addition to paying close attention to potential biases of the study or author(s), a reader should also be alert to one’s own preceding perspective (and biases). Take time to ask oneself: Do I find this paper compelling because it affirms something I already think (or wish) is true? Or am I discounting their findings because it differs from what I expect or from my own work?
The phenomenon of a self-fulfilling prophecy, or expectancy, is well studied in the psychology literature [ 2 ] and is why many studies are conducted in a “blinded” manner [ 3 ]. It refers to the idea that a person may assume something to be true and their resultant behavior aligns to make it true. In other words, as humans and scientists, we often find exactly what we are looking for. A scientist may only test their hypotheses and fail to evaluate alternative hypotheses; perhaps, a scientist may not be aware of alternative, less biased ways to test her or his hypothesis that are typically used in different fields. Individuals with different life, academic, and work experiences may think of several alternative hypotheses, all equally supported by the data.
The author(s) are human too. So, whenever possible, give them the benefit of the doubt. An author may write a phrase differently than you would, forcing you to reread the sentence to understand it. Someone in your field may neglect to cite your paper because of a reference count limit. A figure panel may be misreferenced as Supplemental Fig 3E when it is obviously Supplemental Fig 4E. While these things may be frustrating, none are an indication that the quality of work is poor. Try to avoid letting these minor things influence your evaluation and interpretation of the work.
Similarly, if you intend to share your critique with others, be extra kind. An author (especially the lead author) may invest years of their time into a single paper. Hearing a kindly phrased critique can be difficult but constructive. Hearing a rude, brusque, or mean-spirited critique can be heartbreaking, especially for young scientists or those seeking to establish their place within a field and who may worry that they do not belong.
To truly understand a scientific work, you often will need to look up a term, dig into the supplemental materials, or read one or more of the cited references. This process takes time. Some advisors recommend reading an article three times: The first time, simply read without the pressure of understanding or critiquing the work. For the second time, aim to understand the paper. For the third read through, take notes.
Some people engage with a paper by printing it out and writing all over it. The reader might write question marks in the margins to mark parts (s)he wants to return to, circle unfamiliar terms (and then actually look them up!), highlight or underline important statements, and draw arrows linking figures and the corresponding interpretation in the discussion. Not everyone needs a paper copy to engage in the reading process but, whatever your version of “printing it out” is, do it.
Talking about an article in a journal club or more informal environment forces active reading and participation with the material. Studies show that teaching is one of the best ways to learn and that teachers learn the material even better as the teaching task becomes more complex [ 4 – 5 ]; anecdotally, such observations inspired the phrase “to teach is to learn twice.”
Beyond formal settings such as journal clubs, lab meetings, and academic classes, discuss papers with your peers, mentors, and colleagues in person or electronically. Twitter and other social media platforms have become excellent resources for discussing papers with other scientists, the public or your nonscientist friends, or even the paper’s author(s). Describing a paper can be done at multiple levels and your description can contain all of the scientific details, only the big picture summary, or perhaps the implications for the average person in your community. All of these descriptions will solidify your understanding, while highlighting gaps in your knowledge and informing those around you.
One approach we like to use for communicating how we build on the scientific literature is by starting research presentations with an image depicting a wall of Lego bricks. Each brick is labeled with the reference for a paper, and the wall highlights the body of literature on which the work is built. We describe the work and conclusions of each paper represented by a labeled brick and discuss each brick and the wall as a whole. The top brick on the wall is left blank: We aspire to build on this work and label this brick with our own work. We then delve into our own research, discoveries, and the conclusions it inspires. We finish our presentations with the image of the Legos and summarize our presentation on that empty brick.
Whether you are reading an article to understand a new topic area or to move a research project forward, effective learning requires that you integrate knowledge from multiple sources (“click” those Lego bricks together) and build upwards. Leveraging published work will enable you to build a stronger and taller structure. The first row of bricks is more stable once a second row is assembled on top of it and so on and so forth. Moreover, the Lego construction will become taller and larger if you build upon the work of others, rather than using only your own bricks.
Build on the article you read by thinking about how it connects to ideas described in other papers and within own work, implementing a technique in your own research, or attempting to challenge or support the hypothesis of the author(s) with a more extensive literature review. Integrate the techniques and scientific conclusions learned from an article into your own research or perspective in the classroom or research lab. You may find that this process strengthens your understanding, leads you toward new and unexpected interests or research questions, or returns you back to the original article with new questions and critiques of the work. All of these experiences are part of the “active reading”: process and are signs of a successful reading experience.
In summary, practice these rules to learn how to read a scientific article, keeping in mind that this process will get easier (and faster) with experience. We are firm believers that an hour in the library will save a week at the bench; this diligent practice will ultimately make you both a more knowledgeable and productive scientist. As you develop the skills to read an article, try to also foster good reading and learning habits for yourself (recommendations here: [ 6 ] and [ 7 ], respectively) and in others. Good luck and happy reading!
Thank you to the mentors, teachers, and students who have shaped our thoughts on reading, learning, and what science is all about.
MAC was supported by the PhRMA Foundation's Postdoctoral Fellowship in Translational Medicine and Therapeutics and the University of Virginia's Engineering-in-Medicine seed grant, and KLS was supported by the NIH T32 Global Biothreats Training Program at the University of Virginia (AI055432). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
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I did a survey on the demand for complementary medicine among patients of the gynaecologcial department here in Munich. We collected a couple of hundred questionnaires and I am currently writing my research paper. Since I do not know yet to which journal I am going to submit it, I wanted to adopt a very normal and standard structure/style. I was wondering now whether there are predefined standards of length concerning research papers, in particular regarding word count. I intuitively try to stay under 3000, but would it be ok to exceed that number? Moreover, is it fine to have, for example, a comparatively brief introduction and method section but a rather extensive discussion section? Or do the different sections have predefined standards too?
If you're trying to get a paper that you can publish in a journal, then it really depends on the journal, and if it has any specific requirements or constraints. There is no "standard" length for a paper. I've had papers that were 15 manuscript pages, and papers that were 50.
A temperature-controlled mid-wave infrared polarization radiation source with adjustable degree of linear polarization, optical design of a common-aperture camera for infrared guided polarization imaging, linear polarization demosaicking for monochrome and colour polarization focal plane arrays, validity of kirchhoff's law for semitransparent films made of anisotropic materials, design and fabrication of an ingaas focal plane array integrated with linear-array polarization grating., demosaicking dofp images using newton's polynomial interpolation and polarization difference model., radiation correction method for infrared polarization imaging system with front-mounted polarizer., non-uniformity correction for division of focal plane polarimeters with a calibration method., an overview of polarimetric sensing techniques and technology with applications to different research fields, characterization of a visible spectrum division-of-focal-plane polarimeter., related papers.
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June 18, 2024 report
This article has been reviewed according to Science X's editorial process and policies . Editors have highlighted the following attributes while ensuring the content's credibility:
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by Tomasz Nowakowski , Phys.org
Astronomers have performed a comprehensive chemical study of a Galactic globular cluster known as Terzan 6. Results of the study, presented in a research paper published June 11 on the pre-print server arXiv , could advance our knowledge about the properties and nature of this cluster.
Globular clusters (GCs) are collections of tightly bound stars orbiting galaxies. Astronomers perceive them as natural laboratories enabling studies on the evolution of stars and galaxies. In particular, globular clusters could help researchers to better understand the formation history and evolution of early-type galaxies, as the origin of GCs seems to be closely linked to periods of intense star formation.
Discovered in 1968, Terzan 6 is a highly reddened GC located in the Milky Way's inner bulge, about 23,000 light years away from the Earth. It has an intermediate luminosity, metallicity at a level of -0.62 dex, and its total mass is estimated to be some 100,000 solar masses.
Although Terzan 6 has been known for decades, its chemical composition is poorly studied. That is why a team of astronomers led by Cristiano Fanelli of the Astrophysics and Space Science Observatory of Bologna in Italy, decided to investigate the cluster's chemistry.
The observations were conducted using the Hubble Space Telescope (HST), the Keck II telescope and the Very Large Telescope (VLT), as part of a long-term, ongoing project aimed at studying stellar populations of Galactic bulge GCs.
Fanelli's team has conducted medium-high resolution near-infrared spectroscopy of a representative sample of 27 giant stars, likely members of Terzan 6. All of the investigated stars are within 80 arcseconds from the cluster center, have an average heliocentric velocity of 143.3 km/s and their effective temperatures are between 3,500 and 4,250 K.
Based on this sample of stars, the astronomers found that Terzan 6 has a metallicity of approximately -0.65 dex and does not exhibit any appreciable intrinsic spread in iron. It turned out that calcium, silicon, magnesium, titanium, oxygen, aluminum and sodium have abundance ratios enhanced with respect to the corresponding solar values by about 0.3–0.4 dex. However, the abundance ratio of potassium is only mildly enhanced by an average of 0.11 dex, while carbon and manganese are depleted.
The researchers noted that the inferred chemical abundances indicate that Terzan 6 is a genuine GC of the Galactic bulge. They added that the enhancement in alpha elements like silicon, magnesium or titanium, suggest an old age of the cluster's stellar population, which likely formed at early epochs from a gas mainly enriched by Type II supernovae. Moreover, the spread in the light element abundances points to the presence of first-generation and intermediate second-generation stars in Terzan 6.
"Some scatter in the light element abundances is consistent with the possible self-enrichment of Terzan 6 in these elements during its early lifetime, as is typically observed in Galactic GCs and interpreted as a signature of multiple stellar populations," the authors of the paper concluded.
Journal information: arXiv
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In a new bu-led paper, astrophysicists calculate the likelihood that earth was exposed to cold, harsh interstellar clouds, a phenomenon not previously considered in geologic climate models.
For a brief period of time millions of years ago, Earth may have been plunged out of the sun’s protective plasma shield, called the heliosphere, which is depicted here as the dark gray bubble over the backdrop of interstellar space. According to new research, this could have exposed Earth to high levels of radiation and influenced the climate. Photo courtesy of Opher, et al., Nature Astronomy
Around two million years ago, Earth was a very different place, with our early human ancestors living alongside saber-toothed tigers, mastodons, and enormous rodents . And they may have been cold: Earth had fallen into a deep freeze , with multiple ice ages coming and going until about 12,000 years ago. Scientists theorize that ice ages occur for a number of reasons , including the planet’s tilt and rotation, shifting plate tectonics, volcanic eruptions, and carbon dioxide levels in the atmosphere. But what if drastic changes like these are not only a result of Earth’s environment, but also the sun’s location in the galaxy?
In a new paper published in Nature Astronomy , BU-led researchers find evidence that some two million years ago, the solar system encountered an interstellar cloud so dense that it could have interfered with the sun’s solar wind. They believe it shows that the sun’s location in space might shape Earth’s history more than previously considered.
Our whole solar system is swathed in a protective plasma shield that emanates from the sun, known as the heliosphere. It’s made from a constant flow of charged particles, called solar wind, that stretch well past Pluto, wrapping the planets in what NASA calls a “a giant bubble.” It protects us from radiation and galactic rays that could alter DNA, and scientists believe it’s part of the reason life evolved on Earth as it did. According to the latest paper, the cold cloud compressed the heliosphere in such a way that it briefly placed Earth and the other planets in the solar system outside of its influence.
“This paper is the first to quantitatively show there was an encounter between the sun and something outside of the solar system that would have affected Earth’s climate,” says BU space physicist Merav Opher , an expert on the heliosphere and lead author of the paper.
Her models have quite literally shaped our scientific understanding of the heliosphere, and how the bubble is structured by the solar wind pushing up against the interstellar medium— the space in our galaxy between stars and beyond the heliosphere. Her theory is that the heliosphere is shaped like a puffy croissant , an idea that shook the space physics community. Now, she’s shedding new light on how the heliosphere, and where the sun moves through space, could affect Earth’s atmospheric chemistry.
“Stars move, and now this paper is showing not only that they move, but they encounter drastic changes,” says Opher, a BU College of Arts & Sciences professor of astronomy and member of the University’s Center for Space Physics. She worked on the study during a yearlong Harvard Radcliffe Institute fellowship.
Opher and her collaborators essentially looked back in time, using sophisticated computer models to visualize where the sun was positioned two million years in the past—and, with it, the heliosphere and the rest of the solar system. They also mapped the path of the Local Ribbon of Cold Clouds system, a string of large, dense, very cold clouds mostly made of hydrogen atoms. Their simulations showed that one of the clouds close to the end of that ribbon, named the Local Lynx of Cold Cloud, could have collided with the heliosphere.
If that had happened, says Opher, Earth would have been fully exposed to the interstellar medium, where gas and dust mix with the leftover atomic elements of exploded stars, including iron and plutonium. Normally, the heliosphere filters out most of these radioactive particles. But without protection, they can easily reach Earth. According to the paper, this aligns with geological evidence that shows increased 60Fe (iron 60) and 244Pu (plutonium 244) isotopes in the ocean, Antarctic snow, and ice cores—and on the moon—from the same time period. The timing also matches with temperature records that indicate a cooling period.
“Only rarely does our cosmic neighborhood beyond the solar system affect life on Earth,” says Avi Loeb , director of Harvard University’s Institute for Theory and Computation and coauthor on the paper. “It is exciting to discover that our passage through dense clouds a few million years ago could have exposed the Earth to a much larger flux of cosmic rays and hydrogen atoms. Our results open a new window into the relationship between the evolution of life on Earth and our cosmic neighborhood.”
The outside pressure from the Local Lynx of Cold Cloud could have continually blocked out the heliosphere for a couple of hundred years to a million years, Opher says—depending on the size of the cloud. “But as soon as the Earth was away from the cold cloud, the heliosphere engulfed all the planets, including Earth,” she says. And that’s how it is today.
It’s impossible to know the exact effect the cold cloud had on Earth—like if it could have spurred an ice age. But there are a couple of other cold clouds in the interstellar medium that the sun has likely encountered in the billions of years since it was born, Opher says. And it will probably stumble across more in another million years or so.
Opher and her collaborators are now working to trace where the sun was seven million years ago, and even further back. Pinpointing the location of the sun millions of years in the past, as well as the cold cloud system, is possible with data collected by the European Space Agency’s Gaia mission , which is building the largest 3D map of the galaxy and giving an unprecedented look at the speed stars move.
“This cloud was indeed in our past, and if we crossed something that massive, we were exposed to the interstellar medium,” Opher says. The effect of crossing paths with so much hydrogen and radioactive material is unclear, so Opher and her team at BU’s NASA-funded SHIELD (Solar wind with Hydrogen Ion Exchange and Large-scale Dynamics) DRIVE Science Center are now exploring the effect it could have had on Earth’s radiation, as well as the atmosphere and climate.
“This is only the beginning,” Opher says. She hopes that this paper will open the door to much more exploration of how the solar system was influenced by outside forces in the deep past.
This research was supported by NASA.
Jessica Colarossi is a science writer for The Brink . She graduated with a BS in journalism from Emerson College in 2016, with focuses on environmental studies and publishing. While a student, she interned at ThinkProgress in Washington, D.C., where she wrote over 30 stories, most of them relating to climate change, coral reefs, and women’s health. Profile
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Hi Jessica, this paper was extremely incredible with lots of sense. I always love to explore space and very convinced that life somewhere outside of our solar system exists. I know that the nearest solar system is 4 light years away from us. All the time I think that how we can make it possible to get there within our lifetime span. I know it is impossible but we can still keep thinking about it.
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Title: on conceptualisation and an overview of learning path recommender systems in e-learning.
Abstract: The use of e-learning systems has a long tradition, where students can study online helped by a system. In this context, the use of recommender systems is relatively new. In our research project, we investigated various ways to create a recommender system. They all aim at facilitating the learning and understanding of a student. We present a common concept of the learning path and its learning indicators and embed 5 different recommenders in this context.
Subjects: | Information Retrieval (cs.IR); Artificial Intelligence (cs.AI); Machine Learning (cs.LG) |
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Unlocking the potential of cadmium plating chemistry for low-polarization, long-cycling, and ultrahigh-efficiency aqueous metal batteries †.
* Corresponding authors
a Department of Chemistry, University of Puerto Rico-Rio Piedras Campus, San Juan, PR, USA E-mail: [email protected]
b Department of Physics, University of Puerto Rico-Rio Piedras Campus, San Juan, PR, USA
Aqueous metal batteries represent a compelling avenue for energy storage solutions. Currently, research efforts are heavily concentrated on period 4 transition metals, starting from the prominent zinc to emerging candidates of iron, nickel, copper, and manganese. However, period 5 transition metals remain underexplored and poorly understood. Herein, we selected an underrepresented cadmium metal and investigated its fundamental plating chemistry, which showcases an unprecedented electrode performance, including low polarization (∼5 mV), long lifespan (4000 hours, 5.5 months), and exceptional plating efficiency. Notably, the efficiency approaches unity (99.92%) at 1.0 mA cm −2 and 1.0 mA h cm −2 , and it retains 99.60–99.82% in more aggressive conditions (5–10 mA h cm −2 ; 0.25–0.50 mA cm −2 ). Surprisingly, such a performance is achieved without utilizing sophisticated electrolytes, additives, or surface treatments, which likely results from its suitable Cd 2+ /Cd redox potential, high resistance to hydrogen evolution, and densely stacked plate-like morphology. High-energy, high-rate, and long-cycling cadmium batteries have also been demonstrated. Our work contributes novel insights into the design of high-performance metal batteries.
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S. Katiyar, S. Chang, I. Ullah, W. Hou, A. Conde-Delmoral, S. Qiu, G. Morell and X. Wu, Energy Environ. Sci. , 2024, Advance Article , DOI: 10.1039/D4EE01615G
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Then, writing the paper and getting it ready for submission may take me 3 to 6 months. I like separating the writing into three phases. The results and the methods go first, as this is where I write what was done and how, and what the outcomes were. In a second phase, I tackle the introduction and refine the results section with input from my ...
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The use of e-learning systems has a long tradition, where students can study online helped by a system. In this context, the use of recommender systems is relatively new. In our research project, we investigated various ways to create a recommender system. They all aim at facilitating the learning and understanding of a student. We present a common concept of the learning path and its learning ...
Currently, research efforts are heavily concentrated on period 4 transition metals, starting from the prominent zinc to emerging candidates of iron, nickel, copper, and manganese. ... long-cycling, and ultrahigh ... Paper. Submitted 12 Apr 2024. Accepted 04 Jun 2024. First published 05 Jun 2024. Download Citation.
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