Tag Archive | "college of arts and sciences"

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Rocket Research Confirms X-Ray Glow Emanates from Galactic Hot Bubble


A University of Miami scientist led a NASA rocket mission to measure the diffuse X-ray background in space, revealing a “local hot bubble” and settling a debate.

Hot.Bubble.Rocket

UM’s Massimiliano Galeazzi, in blue on the left, and his collaborators ready the sounding rocket for launch with NASA engineers.

By Marie Guma-Diaz and Annette Gallagher

CORAL GABLES, Fla. (July 27, 2014) — When we look up to the heavens on a clear night, we see an immense dark sky with uncountable stars. With a small telescope we can also see galaxies, nebulae, and the disks of planets. If you look at the sky with an X-ray detector, you would see many of these same familiar objects; in addition, you would see the whole sky glowing brightly with X-rays. This glow is called the “diffuse X-ray background.”

While, at higher energies, the diffuse emission is due to point sources too far away and faint to be seen individually, the origins of the soft X-ray glow have been controversial, even 50 years after it was first discovered. The longstanding debate centers around whether the soft X-ray emission comes from outside our solar system, from a hot bubble of gas called the local hot bubble, or whether the emission comes from within the solar system, due to the solar wind colliding with diffuse gas.

New findings settle this controversy. A study published online Sunday in the journal Nature shows that the emission is dominated by the local hot bubble of gas (1 million degrees), with, at most, 40 percent of the emission originating within the solar system. The findings should put to rest the disagreement about the origin of the X-ray emission and confirm the existence of the local hot bubble.

“We now know that the emission comes from both sources, but is dominated by the local hot bubble,” said Massimiliano Galeazzi, professor and associate chair in the Department of Physics in the College of Arts and Sciences, and principal investigator of the study. “This is a significant discovery. Specifically, the existence or nonexistence of the local bubble affects our understanding of the galaxy close to the sun and can be used as the foundation for future models of the galaxy structure.”

Galeazzi, who led the investigation, and his collaborators from NASA, the University of Wisconsin-Madison, the University of Michigan, the University of Kansas, the Johns Hopkins University and CNES in France, launched a sounding rocket to analyze the diffuse X-ray emission, with the goal of identifying how much of that emission comes from within our solar system and how much from the local hot bubble.

 “The DXL team is an extraordinary example of cross-disciplinary science, bringing together astrophysicists, planetary scientists, and heliophysicists,” said F. Scott Porter, astrophysicist at NASA’s Goddard Space Flight Center. “It’s unusual but very rewarding when scientists with such diverse interests come together to produce such groundbreaking results.”

The study measured the diffuse X-ray emission at low energy, what is referred to as the 1/4 keV band, corresponding to radiation with wavelength of the order of 5 nm.

“At that low energy, the light gets absorbed by the neutral gas in our galaxy, so the fact that we observe it means that the source must be ‘local,’ possibly within a few hundred light-years from earth,” Galeazzi said. “However, until now it was unclear whether it comes from within the solar system (within few astronomical units from earth), or a very hot bubble of gas in the solar neighborhood (hundreds of light-years from earth). This is like traveling at night and seeing a light, not knowing if the light comes from 10 yards or 1,000 miles away.”

Interstellar bubbles are probably created by stellar winds and supernova explosions, which cast material outward, forming large cavities in the interstellar medium—the material that fills the space between the stars in a galaxy. Hot X-ray emitting gas can fill the bubble, if a second supernova occurs within the empty cavity.

X-ray emission also occurs within our solar system when the solar wind collides with interplanetary neutral gas. The solar wind is a stream of charged particles released, with great energy, from the atmosphere of the sun. They create a solar wind that travels vast distances, forming a region called the heliosphere. As these particles travel through space at supersonic speeds, they may collide with neutral hydrogen and helium that enters the solar system due to the motion of the sun in the galaxy, capturing an electron and emitting X-rays. This is called the solar wind charge exchange process.

The team refurbished and modernized an X-ray detector that was mounted on a sounding rocket. The X-ray detector was originally flown by the University of Wisconsin-Madison on multiple missions during the 1970s to map the soft X-ray sky. The current team, led by Galeazzi, rebuilt, tested, calibrated, and adapted the detectors to a modern NASA suborbital sounding rocket. Components from a 1993 Space Shuttle mission also were used. The sounding rocket mission, known as “The Diffuse X-ray emission from the Local Galaxy,” aimed at separating and quantifying the X-ray emission from the two suspected sources: the local hot bubble and the solar wind charge exchange. This was the first mission designed for this kind of study.

“X-ray telescopes on satellites can observe for long periods of time and have reasonably large collecting areas, but very tiny fields of view, so they are very good for studying a small area in great detail,” said Dan McCammon, professor of physics at the University of Wisconsin-Madison and one of the scientists who built the original instrument. “However, the observations for this experiment needed to look at a large part of the sky in a short time, to make sure the solar wind did not change during the measurements. The sounding rocket could do it 4,000 times faster.”

 The rocket was launched with the support of NASA’s Wallops Flight Facility, from White Sands Missile Range in New Mexico, on December 12, 2012. It reached an altitude of 258 km (160 miles), and stayed above the Earth’s atmosphere for five minutes, enough time to carry out its mission successfully. The information collected was transmitted directly to researchers on the ground at the launch facility.

“The sounding rocket program allows us to conduct high-risk, high-payoff science quickly and inexpensively,” Porter said. “It is really one of NASA’s crown jewels.”

Galeazzi and collaborators are already planning the next launch, planned for December 2015. That mission will be similar in design and goals, but will have multiple instruments to characterize the emission in more detail.

The Nature article is titled “The origin of the ‘local’ ¼ keV X-ray flux in both charge exchange and a hot bubble.” Other authors are M. Chiao, M.R. Collier, F. S. Porter, S. L. Snowden, N. E. Thomas and B. M. Walsh, from NASA’s Goddard Space Flight Center; T. Cravens and I. Robertson, from Department of Physics and Astronomy, University of Kansas; D. Koutroumpa, from Universitè Versailles St-Quentin; Sorbonne Universitès & CNRS/INSU, LATMOS-IPSL; K.D. Kuntz, from The Henry A. Rowland Department of Physics and Astronomy, Johns Hopkins University; R. Lallement, from GEPI Observatoire de Paris, CNRS, Université Paris Diderot; S. T. Lepri from the Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan; D. McCammon and K. Morgan, from the Department of Physics, University of Wisconsin-Madison; and Y. Uprety and E. Ursino, from the UM Department of Physics.

Annette Gallagher can be reached at 305-284-1121.

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President Shalala Weighs in on ‘The Risky Business’ of Climate Change

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President Shalala Weighs in on ‘The Risky Business’ of Climate Change


By Megan Ondrizek
UM News

UM President Donna E. Shalala.

UM President Donna E. Shalala.

CORAL GABLES, Fla. (June 24, 2014) — On Tuesday, University of Miami President Donna E. Shalala joined the debate on climate change as a member of The Risky Business Project, a joint, non-partisan initiative. Shalala partnered with fellow former political leaders to discuss global trends and the economic risks of climate change. Read the full story

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Scientists Develop ‘Nanosubmarines’ to Deliver Molecules Inside Cells


By Marie Guma-Diaz
UM News

The nanoparticles, which are capable of delivering and exchanging complementary molecules, emit a fluorescent signal that can be observed with a microscope.

The nanoparticles, which are capable of delivering and exchanging complementary molecules, emit a fluorescent signal that can be observed with a microscope.

CORAL GABLES, Fla. (June 26, 2014) —With the need for very small devices in therapeutic applications continuing to grow, demand for the development of nanoparticles that can transport and deliver drugs to target cells in the human body is reaching new heights.

Recently, a team of researchers created nanoparticles that, under the right conditions, can self-assemble, trapping complementary guest molecules within their structure. Like tiny submarines, these versatile nanocarriers can navigate in the watery environment surrounding cells and transport their guest molecules through the membrane of living cells to sequentially deliver their cargo.

Although the transport of molecules inside cells with nanoparticles has been previously achieved using various methods, researchers have developed nanoparticles capable of delivering and exchanging complementary molecules. For practical applications, these nanocarriers are highly desirable, explains Francisco Raymo, professor of chemistry in the University of Miami College of Arts and Sciences and lead investigator of the project.

“The ability to deliver distinct species inside cells independently and force them to interact, exclusively in the intracellular environment, can evolve into a valuable strategy to activate drugs inside cells,” said Raymo.

The new nanocarriers are 15 nanometers in diameter. They are supramolecular constructs made of building blocks called amphiphilic polymers. These nanocarriers hold the guest molecules within the confines of their water-insoluble interior and use their water-soluble exterior to travel through an aqueous environment. As a result, these nanovehicles are ideal for transferring molecules, which would otherwise be insoluble in water, across a liquid environment.

“Once inside a living cell, the particles mix and exchange their cargo. This interaction enables the energy transfer between the internalized molecules,” said Raymo, director of UM’s Laboratory for Molecular Photonics. “If the complementary energy donors and acceptors are loaded separately and sequentially, the transfer of energy between them occurs exclusively within the intracellular space. As the energy transfer takes place, the acceptors emit a fluorescent signal that can be observed with a microscope.”

Essential to this mechanism are the noncovalent bonds that loosely hold the supramolecular constructs together. These weak bonds exist between molecules with complementary shapes and electronic properties. They are responsible for the ability of supramolecules to assemble spontaneously in liquid environments. Under the right conditions, the reversibility of these weak noncovalent contacts allows the supramolecular constructs to exchange their components as well as their cargo.

The experiments were conducted with cell cultures. It is not yet known if the nanoparticles can actually travel through the bloodstream.

“That would be the dream, but we have no evidence that they can actually do so,” said Raymo. “However, this is the direction we are heading.”

The next phase of this investigation involves demonstrating that this method can be used to do chemical reactions inside cells, instead of energy transfers.

“The size of these nanoparticles, their dynamic character, and the fact that the reactions take place under normal biological conditions (at ambient temperature and neutral environment) makes these nanoparticles an ideal vehicle for the controlled activation of therapeutics directly inside the cells,” Raymo says.

The study,  “Intracellular guest exchange between dynamic supramolecular hosts,” is published in the Journal of the American Chemical Society. Co-authors are John F. Callan, co-corresponding author, from the School of Pharmacy and Pharmaceutical Sciences at the University of Ulster; Subramani Swaminathan and Janet Cusido, from UM’s Laboratory for Molecular Photonics in the Department of Chemistry; and Colin Fowley and Bridgeen McCuaghan, from the School of Pharmacy and Pharmaceutical Sciences at the University of Ulster.

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Unraveling the Secrets of Speciation

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Unraveling the Secrets of Speciation


By Robert C. Jones Jr.
UM News

 

J. Albert C. Uy, the Aresty Chair in Tropical Ecology in UM’s Department of Biology, studies the origin of biological species, using tropical birds like this monarch flycatcher as the primary organism. (Photo by Day's Edge Productions)

J. Albert C. Uy, the Aresty Chair in Tropical Ecology in UM’s Department of Biology, studies the origin of biological species, using tropical birds like this monarch flycatcher as the primary organism. (Photo by Floria Mora-Kepfer)

CORAL GABLES, Fla. (June 12, 2014) – J. Albert C. Uy makes the trip about twice a year, flying first to Guadalcanal, where U.S. Marines once fought a famous battle more than 60 years ago, then to Makira, the southernmost atoll in the Solomon Islands chain. There, he lives and works for up to three weeks at a stretch, studying a particular group of island inhabitants who, though small, may hold a big secret to understanding the process of speciation. Read the full story

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Art Historian and Veteran Curator Named Director of the Lowe

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Art Historian and Veteran Curator Named Director of the Lowe


Special to UM News

Jill Deupi

Jill Deupi

CORAL GABLES, Fla. (June 3, 2014) – The University of Miami has appointed Jill Deupi, the current director and chief curator of University Museums at Fairfield University, as the new director of the Lowe Art Museum.

“I am honored to have been selected to lead the Lowe Art Museum as it embarks on an exciting new chapter in its rich and storied history,” Deupi said. “The museum is perfectly poised to catapult itself to the next level, building upon its tremendous resources and past successes while embracing 21st-century museum practice, contemporary art and culture, new education modalities, and, above all, participatory learning.”

Deupi credits the Lowe’s solid foundation and Miami’s effervescent arts scene for her decision to join UM, beginning August 11. One of her goals for the museum is “to connect its remarkable collections to the contemporary art world and current cultural trends.” She hopes to accomplish this partly with enhanced public accessibility to the Lowe’s holdings via an online, user-friendly database.

“We selected Dr. Jill Deupi as the new director of the Lowe after an extensive search,” said UM College of Arts & Sciences Dean Leonidas Bachas. “Her distinguished museum experience and academic background in art and art history as well as her enthusiasm to involve our students in experiential learning are a perfect combination for the Lowe to expand its reach as a didactic resource for the University and local community.”

In addition to her leadership roles at the University Museums at Fairfield University, Deupi also has served as an assistant professor of art history since 2008. Under Deupi’s leadership as founding director, the Bellarmine Museum of Art has welcomed thousands of visitors since it opened to the public in late 2010. Deupi has curated nearly 20 temporary exhibitions at the Bellarmine and at Fairfield’s Thomas J. Walsh Art Gallery, which she also has directed since 2013.

Opened in 1952, the University of Miami’s Lowe Art Museum is Miami-Dade County’s oldest and only comprehensive visual arts institution, featuring the region’s most diverse collection of world art. The Lowe’s distinguished permanent collection spans 5,000 years of western and non-western art history, highlights of which can be seen in the museum’s nine galleries. Brian Dursum, director of the Lowe Art Museum since 1990, announced his retirement in September 2013.

Part of the UM College of Arts & Sciences, the Lowe also mounts distinguished temporary exhibitions throughout the year, accompanied by an array of complementary programming. With its mission to serve the University of Miami, greater South Florida communities, and national and international visitors as a teaching and exhibiting resource, the Lowe presents a unique art experience, with broad-based collections and one-of-a-kind works of art.

A fellow of the American Academy in Rome, Deupi wrote her doctoral dissertation on art and cultural politics in 18th century Naples. Her prior museum experience includes work at the Royal Academy of Arts, London; the Art Institute of Chicago; the Snite Museum of Art, University of Notre Dame, Indiana; the National Gallery of Art, Washington, D.C.; and the Wallace Collection, London. Although her area of scholarly expertise is 18th-century European art, neoclassicism, and museology, Deupi possesses an impressive breadth of art historical knowledge: she has curated exhibitions devoted to 20th- and 21st-century photography; mid-century American painting; contemporary sculpture; ancient Chinese funerary sculpture; 20th-century portraiture; and 20th-century Venetian glass (among others).

Highlights from Deupi’s programming achievements include the establishment of a distinguished lecture series in the visual arts, funded by the Robert Lehman Foundation; the implementation of a successful Family Day program at the Bellarmine Museum; and the development of a broad range of programming in arts education and engagement, including a cultural tours abroad program. She also worked tirelessly to secure significant external support from a range of donors, corporate sponsors, and foundations.

Deupi received her B.A. from Mount Holyoke College and her J.D. from American University’s Washington College of Law, graduating summa cum laude. She holds both an M.A. and a Ph.D. in art history from the University of London’s Birkbeck College and the University of Virginia, respectively. She serves as a board member of the Association of Academic Museums and Galleries (AAMG) and co-chair of the New England Museums Association’s (NEMA) Academic Professional Affinity Group. She also sits on the steering committee of the Cultural Alliance of Fairfield County’s Executive Directors Network and is a member of the American Alliance of Museums (AAM), the Association of Art Museum Curators (AAMC), the College Art Association (CAA), and the International Council of Museums (ICOM).

Deupi has juried a number of art competitions and exhibitions and has served as an external reviewer for the National Endowment for the Humanities. She has authored numerous exhibition publications as well as the chapter “The Antique Legacy from the Middle Ages to the Enlightenment,” which appears in A Companion to Greek Art (Blackwell Publishing, 2012).

Deupi currently lives in Fairfield with her husband and three children.

 

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