Tag Archives: classify

NASA Astronomers Classify Near-Earth Asteroids: Latest Findings – Sciworthy

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Researchers exploring the solar system’s history focus on a diverse range of comets and asteroids, particularly those classified as Near-Earth Objects (NEOs). These celestial bodies not only offer insights into the origins of water and organic materials but also continue to impact planets across the solar system, including Mars, Earth, Venus, and Mercury. Their close proximity to Earth facilitates detection and observation with smaller telescopes, increasing the potential for successful interceptions, potentially involving rovers and landers.

An international research team has recently classified and identified 39 new NEOs between February 2021 and September 2024, utilizing two advanced telescopes: Itaparica Observatory (OASI) in Brazil, along with the 2.15-meter Jorge Sahade telescope at Complejo Astronomico El Leoncito (CASLEO) in Argentina.

The research team used these telescopes to study variations in the brightness of NEOs over time. Since NEOs are essentially blocks of ice or rock that reflect sunlight rather than emit light, their visibility from Earth is influenced by the angle between Earth and the Sun along with their size, shape, and structure. By measuring the periodic changes in brightness, scientists calculated the rotation rates of these objects.

The diameters of the 39 NEOs varied from 0.1 to 10 kilometers (0.06 to 6 miles), with most ranging between 0.5 to 3 kilometers (0.3 to 2 miles). Their shapes ranged from nearly spherical to elongated, cigar-like forms. The team successfully determined the rotation periods for 26 of these NEOs, noting that the shortest rotation cycle was just over two hours while the longest approached 20 hours. Notably, 16 of these NEOs rotated in under 5 hours, suggesting that many are fast-rotating bodies.

The study established that a rotation period exceeding 2.2 hours is the upper limit for small NEOs known as rubble pile asteroids, which are loose formations held together by self-gravity. Beyond this threshold, centrifugal forces could destabilize them. Conversely, those NEOs under 250 meters (820 feet) tend to be more solid, dubbed monoliths. The findings indicated that smaller and medium-sized NEOs exhibit varied structures and formation histories.

Using advanced imaging techniques through telescope lenses that filter specific light wavelengths, the researchers analyzed the chemical composition of 34 NEOs. They employed 2 additional filters alongside 4 filters designed for green and red wavelengths, including near-infrared wavelengths. Their results revealed that 50% of the NEOs are silica-based, resembling many terrestrial rocks, with 23.5% comprising carbon-rich materials, approximately 9% metals, and around 6% basaltic elements. The remaining composition was a mixture of carbon and silicates as well as calcium and aluminum.

While the chemical analysis largely aligned with previous findings, the researchers found a lack of olivine—a mineral typically prevalent in smaller asteroids. This absence can be attributed to the fact that most sampled NEOs exceeded 200 meters (660 feet), surpassing the typical size for olivine-rich asteroids.

This research enriches our understanding of NEOs and their physical and chemical properties. The team advocates for an integrated research approach that leverages technology and multi-telescope observations to effectively characterize small celestial objects. Future studies should prioritize close monitoring of NEOs, especially those approaching their rotation threshold, and employ radar observations to confirm the existence of potential binary pairs. By analyzing reflected visible and near-infrared light, researchers can further unveil the chemical makeup of the asteroid surfaces.


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Researchers Utilize Enhanced DNA Techniques to Classify Breast Cancer

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Triple-negative breast cancer (TNBC) is recognized as one of the more aggressive and challenging breast cancers to treat. Lacking the three standard hormonal markers associated with estrogen receptors, progesterone receptors, and HER2, this absence complicates the selection of effective treatment strategies for healthcare providers.

Researchers characterize TNBC as a collection of various diseases with distinct molecular characteristics that impact how the cancer manifests and its response to treatments. They utilize specific genes and gene products to categorize TNBC types. It is important to note that there are overlaps in the current classifications, which might be explained by the presence and levels of particular chemical molecules on the DNA. These molecules play a role in regulating whether genes are activated or deactivated in cells through processes known as DNA methylation.

In this study, researchers from Sweden explored how the distribution and patterns of DNA methylation delineate different forms of TNBC, influencing tumor behavior and interactions with the body’s immune system and its treatment responses. They analyzed 235 tumor samples from various patients in Sweden, ensuring that the data was refined to focus solely on cancerous cells rather than healthy tissue.

Employing a statistical technique known as Non-negative matrix factorization, they identified two primary categories of TNBC based on DNA methylation patterns: basal and nonbasal groups. This categorization aligns with previous classifications grounded in how cells interpret gene functions, termed gene expression. The basal group comprised tumors that were typically more active in immune responses and had a higher incidence of mutations linked to DNA repair issues, notably involving the common BRCA1 gene. Conversely, although the nonbasal group lacked hormone receptors, they exhibited increased activity in genes that influence hormonal responses.

Utilizing statistical assessments, the researchers subdivided each major group into smaller subtypes. Within the basal tumors, they identified three subgroups, referred to as basal1, basal2, and basal3, characterized by varying levels of immune cell activity and gene expression profiles. One specific subgroup, Basal3, demonstrated elevated expression of proteins that aid tumors in evading the immune system. The researchers found that specific DNA methylation patterns could activate or deactivate these proteins, indicating that patients with basal tumors might benefit from existing cancer treatments targeting this protein. The Basal2 subgroup expressed genes that inhibit immune activity, while the Basal1 subgroup displayed no significant immune-related behavior.

In the nonbasal category, researchers distinguished two subtypes: nonbasal1 and nonbasal2. Both of these subgroups were more prevalent among older patients and exhibited lower survival rates compared to the basal subgroup. The Nonbasal2 group encompassed tumors that influenced hormonal activity and responses to fatty treatments, whereas the Nonbasal1 group experienced more frequent disruptions in genes associated with tumor suppression.

Across all groups, researchers identified numerous genes whose methylation could modulate tumor growth and responses to the surrounding environment. To validate their findings in a broader context, they sourced independent tumor datasets from global databases and conducted similar classification analyses. They confirmed that the identified methylation subtypes appeared in other TNBC samples and correlated methylation patterns with tumor defense mechanisms, pinpointing strategies TNBC tumors may utilize to evade the immune system.

The researchers also acknowledged several limitations of their study. Their focus on DNA methylation represents just one of many chemical modifications that can influence TNBC behavior. Some of the independent datasets utilized originated from general breast cancer studies and were not exclusively focused on TNBC. Additionally, a significant portion of the data came from Western and Northern European populations, which may limit the applicability of the findings to individuals from other ethnicities. They emphasized the necessity for larger and more diverse datasets to gain a comprehensive understanding of TNBC subtypes.

In conclusion, the researchers posited that examining DNA methylation in patient samples could effectively categorize TNBC into meaningful subtypes, each with unique biological features, immune environments, and potential treatment responses. They recommended that future studies explore the origins of epigenetic modifications, such as DNA methylation, and how these alterations contribute to variations in TNBC subtypes.


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Astronomers suggest a new way to classify planets

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The current definition, established by the International Astronomical Union in 2006, states that to be considered a planet, an object must be in the solar system and orbit the Sun. However, this definition is problematic in that it is not quantitative and excludes exoplanets. A proposed new definition states that an object can orbit one or more stars, brown dwarfs, or stellar remnants, and sets a mass limit that should apply to any planet.

Artist's impression of an exoplanet and its host star. Image courtesy of Sci.News.

In 2006, the International Astronomical Union (IAU) adopted Resolution B5, which defines a planet as a celestial body that (a) orbits the Sun, (b) has sufficient mass so that its own gravity overcomes the forces of a rigid body, has a shape in hydrostatic equilibrium (approximately circular), and (c) is swept around its orbit.

“The current definition specifically mentions orbiting the sun,” said Professor Jean-Luc Margot of the University of California, Los Angeles.

“Thousands of planets are currently known to exist, but the IAU definition only applies to planets in our solar system.”

“We propose a new definition that can be applied to objects orbiting any star, stellar remnant, or brown dwarf.”

Prof Margot and his colleagues argue that the requirement to orbit the Sun is too specific, while other criteria in the IAU definition are too vague.

For example, it says that the planet has “gone out of orbit,” but doesn't say what that means.

The proposed new definition includes quantifiable criteria that can be applied to define planets inside and outside the solar system.

Under the new definition, a planet is (a) an object that orbits one or more stars, brown dwarfs, or stellar remnants; (b) a mass greater than or equal to 10twenty three kg, (c) is 13 times the mass of Jupiter (2.5 × 1028 kg).

The authors ran mathematical algorithms on the properties of objects in the solar system to determine which ones are densely populated.

This analysis reveals groups of distinct properties common to planets in our solar system, which can be used as a starting point for creating a general classification of planets.

For example, if an object's gravitational force is sufficient to accumulate or eject smaller objects nearby to clear a path, the object is said to be dynamically dominant.

“All planets in the solar system are dynamically dominated, but other objects, including dwarf planets like Pluto and asteroids, are not, so this property can be included in the definition of a planet,” Prof Margot said.

Dynamic dominance requirements dictate a lower mass limit.

But it's also possible that the potential planet is too large to fit the new definition.

For example, some gas giants can grow so large that thermonuclear fusion of deuterium occurs, and the object becomes a star known as a brown dwarf, no longer a planet. This limit has been determined to be more than 13 Jupiter masses.

On the other hand, the current requirement that it be spherical is more problematic.

Distant planets are rarely observed in enough detail to determine their shapes with certainty.

The researchers argue that even though planets are generally round, the shape requirements would be so difficult to implement that they are virtually useless for definitional purposes.

“Fixing the definition to mass, the quantity that is most easily measured, eliminates debate about whether a particular object meets the criteria – this is a weakness of the current definition,” said Dr Brett Gladman, a researcher at the University of British Columbia.

“The good news is that in the solar system,twenty one kg looks round.”

“Thus, any object that meets the proposed lower mass limit of 10twenty three kg is expected to be spherical.”

Team paper Published in Planetary Science Journal.

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Jean-Luc Margot othersA quantitative criterion for defining planets. Planet Science Journal 5,159; doi: 10.3847/PSJ/ad55f3

Source: www.sci.news