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Hairy Interfaces by Alice Nasto

Feb 23, 2018, 11:00 AM-12:00 PM

Room 202/204

Host: Joey Paulsen | Contact: David Yllanes (dyllanes@syr.edu)

 Textured surfaces are known to play an important role in water-repellency and uptake for a number of creatures. While the influence of chemistry and surface roughness on the wettability of surfaces has been studied extensively, little is known about the role of larger objects such as hairs. Our work is directed towards rationalizing the benefits gained from hairy textures through a combined experimental and theoretical approach. 

First, we are motivated by semi-aquatic mammals, who rely on fur for insulation underwater. We investigate the mechanism of dynamic air entrainment for hairy surfaces plunged in liquid. Hairy surfaces that are fabricated using laser cut molds and casting samples with PDMS are plunged into a fluid bath. Modeling the hairy texture as a network of capillary tubes, the imbibition speed of water into the hairs is obtained through a balance of hydrostatic pressure and viscous stress. The maximum diving depth that can be achieved before the hairs are wetted to the roots is predicted from a comparison of the diving speed and imbibition speed. 

Second, motivated by nectar-drinking animals with hairy tongues, we investigate the reverse scenario, where a hairy surface is withdrawn from a bath of fluid, emerging with viscous liquid entrained in the hairy texture. The drainage of the liquid trapped between the texture is modeled using a Darcy-Brinkmann like approach. The amount of fluid that is entrained depends on the viscosity of the fluid, the density of the hairs, and the withdrawal speed. Both theory and experiments show that there is an optimal hair density to maximize fluid uptake. 

Finally, we investigate drop impact on hairy surfaces. By varying the speed of the drop at impact and the spacing of the hairs, we observe a variety of behaviors. For dense hairs and low impact velocity, the liquid drop sits on top of the hair, similar to a Cassie-Baxter state. For higher impact velocity, and intermediate to high density of hairs, the drops penetrate through the surface, but the hairs resist their spreading. For low hair density and high impact velocity, the drops penetrate and eject droplets upon impact. 

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Multimessenger astrophysics with numerical relativity by David Radice

Feb 26, 2018, 3:30 PM-4:45 PM

Room: 202/204 Physics Bldg.

Host: Prof.Duncan Brown/ Contact: Yudaisy Salomón Sargentón, 315-443-5960

How are neutron stars formed and what is inside them? What is the  engine powering short gamma-ray bursts? What is the astrophysical site  of production of heavy elements? Multimessenger observations of compact binary coalescence and core-collapse supernovae might provide  us with the key to answer these and other important open questions in theoretical astrophysics. However, multimessenger astronomy also poses  new challenges to the theorists who need to develop models for the  joint interpretation of all data channels. In this talk, I will  present recent theoretical results. I will review the landmark multimessenger observation of merging neutron stars, and I will discuss its interpretation and implication in the light of results from first-principles simulations. Finally, I will discuss future challenges and prospective for this nascent field.

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TBD by Elisabeth Agoritsas

Mar 16, 2018, 11:00 AM-12:00 PM

Room 202/204

Host: Lisa Manning | Contact: David Yllanes (dyllanes@syr.edu)

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TBD by Emlyn Hughes

Mar 22, 2018, 3:30 PM-4:45 PM

Room: 202/204 Physics Bldg.

Host: Prof. Paul Souder / Contact: Yudaisy Salomón Sargentón, 315-443-5960

CM

TBD by Ann Hermundstad

Mar 23, 2018, 11:00 AM-12:00 PM

Room 202/204

Host: Lisa Manning | Contact: David Yllanes (dyllanes@syr.edu)

HE

TBA Bhaskar Dutta

Mar 23, 2018, 12:00 PM-1:30 PM

208 Physics Bldg.

Host: Scott Watson/ Contact: Yudaisy Salomón Sargentón, 315-443-5960

HE

TBA Joel Giedt

Mar 26, 2018, 2:00 PM-3:00 PM

202 Physics Bldg.

Host: Simon Catterall/ Contact: Yudaisy Salomón Sargentón, 315-443-5960

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TBD by Adam Frank

Mar 29, 2018, 3:30 PM-4:45 PM

Room: 202/204 Physics Bldg.

Host: Prof. Peter Saulson/ Contact: Yudaisy Salomón Sargentón, 315-443-5960

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TBA Aaron Held

Apr 9, 2018, 2:00 PM-3:00 PM

202 Physics Bldg.

Host: Jack Laiho/ Contact: Yudaisy Salomón Sargentón, 315-443-5960

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TBD by Nick Vamivakas

Apr 12, 2018, 3:30 PM-4:45 PM

Room: 202/204 Physics Bldg.

Host: Prof. Matt LaHaye / Contact: Yudaisy Salomón Sargentón, 315-443-5960

HE

TBA Fleur Versteegen

Apr 13, 2018, 12:00 PM-1:30 PM

208 Physics Bldg.

Host: Jack Laiho/ Contact: Yudaisy Salomón Sargentón, 315-443-5960

HE

TBA Walter Tangarife

Apr 16, 2018, 2:00 PM-3:00 PM

202 Physics Bldg.

Host: Jay Hubisz/ Contact: Yudaisy Salomón Sargentón, 315-443-5960

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TBD by Sarah M. Milkovich

Apr 19, 2018, 3:30 PM-4:45 PM

Room: 202/204 Physics Bldg.

Host: Prof. Steven Blusk/ Contact: Yudaisy Salomón Sargentón, 315-443-5960

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TBA Sungwoo Hong

Apr 20, 2018, 12:00 PM-1:30 PM

208 Physics Bldg.

Host: Judah Unmuth-Yockey/ Contact: Yudaisy Salomón Sargentón, 315-443-5960

HE

TBA Yannick Meurice

Apr 23, 2018, 2:00 PM-3:00 PM

202 Physics Bldg.

Host: Judah Unmuth-Yockey/ Contact: Yudaisy Salomón Sargentón, 315-443-5960

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TBD by Vernita Gordon

Apr 26, 2018, 3:30 PM-4:45 PM

Room: 202/204 Physics Bldg.

Host: Prof. Lisa Manning/ Contact: Yudaisy Salomón Sargentón, 315-443-5960

CM

TBD by Tim Atherton

Apr 27, 2018, 11:00 AM-12:00 PM

Room 202/204

Host: Joey Paulsen | Contact: David Yllanes (dyllanes@syr.edu)

HE

TBA Jim Halverson

Apr 27, 2018, 12:00 PM-1:30 PM

208 Physics Bldg.

Host: Scott Watson/ Contact: Yudaisy Salomón Sargentón, 315-443-5960

HE

Taking the measure of neutron stars with NICER

Apr 30, 2018, 2:00 PM-3:00 PM

202 Physics Bldg.

Host: Jack Laiho/ Contact: Yudaisy Salomón Sargentón, 315-443-5960

The Neutron Star Interior Composition Explorer (NICER) is NASA's new X-ray timing instrument onboard the ISS that was launched in June 2017. With a large effective area, low background, very precise absolute timing and great low energy response, NICER has been doing a fantastic job in observing many interesting phenomena related to neutron stars and black holes. One of the main goals of the NICER mission is to constrain the equation of state of ultra-dense matter by measuring the masses and radii of several rotation-powered millisecond pulsars. This is being done by fitting pulse waveform models that incorporate all relevant relativistic effects and atmospheric radiation transfer processes to the periodic soft X-ray modulations produced by the rotation of hot spots located near the magnetic polar caps of these pulsars. Some of the other interesting topics that are being studied with NICER includes phenomena related to Type I X-ray bursts, which are thermonuclear flashes observed from the surfaces of accreting neutron stars in Low Mass X-ray Binaries, such as photospheric radius expansion and burst oscillations. NICER's large effective area and excellent low energy response enable new, detailed studies of these bursts in the soft X-ray band. In this talk I will present some of the early results from the first nine months of the NICER mission and will report on the progress being made by the NICER team in measuring the masses and radii of pulsars.