Scattering for radial, semi-linear, super-critical wave equations with bounded critical norm

In this paper we study the focusing cubic wave equation in 1+5 dimensions with radial initial data as well as the one-equivariant wave maps equation in 1+3 dimensions with the model target manifolds $\mathbb{S}^3$ and $\mathbb{H}^3$. In both cases the scaling for the equation leaves the $\dot{H}^{\frac{3}{2}} \times \dot{H}^{\frac{1}{2}}$-norm of the solution invariant, which means that the equation is super-critical with respect to the conserved energy. Here we prove a conditional scattering result: If the critical norm of the solution stays bounded on its maximal time of existence, then the solution is global in time and scatters to free waves both forwards and backwards in infinite time. The methods in this paper also apply to all supercritical power-type nonlinearities for both the focusing and defocusing radial semi-linear equation in 1+5 dimensions, yielding analogous results.Comment: 59 pages, minor typos have been correcte

The KaVA and KVN Pulsar Project

We present our work towards using the Korean VLBI (Very Long Baseline Interferometer) Network (KVN) and VLBI Exploration of Radio Astronomy (VERA) arrays combined into the KVN and VERA Array (KaVA) for observations of radio pulsars at high frequencies ($\simeq$22-GHz). Pulsar astronomy is generally focused at frequencies approximately 0.3 to several GHz and pulsars are usually discovered and monitored with large, single-dish, radio telescopes. For most pulsars, reduced radio flux is expected at high frequencies due to their steep spectrum, but there are exceptions where high frequency observations can be useful. Moreover, some pulsars are observable at high frequencies only, such as those close to the Galactic Center. The discoveries of a radio-bright magnetar and a few dozen extended Chandra sources within 15 arc-minute of the Galactic Center provide strong motivations to make use of the KaVA frequency band for searching pulsars in this region. Here, we describe the science targets and report progresses made from the KVN test observations for known pulsars. We then discuss why KaVA pulsar observations are compelling.Comment: To appear in PASJ KaVA Special Issu

Responding to Cybersecurity Challenges: Securing Vulnerable U.S. Emergency Alert Systems

Emergency alert systems (EASs) in the United States (US) form part of the nation’s critical infrastructure. These systems rely on aging platforms and suffer from a fragmented interconnected network of partnerships. Some EASs have an easily identifiable vulnerability: one can access their management website via the Internet. Authorities must secure these systems quickly. Other concerns also exist, such as the lack of policies for reporting vulnerabilities. To begin to assess EASs in the US, we used Shodan to evaluate the availability of these websites in six southeastern states. We found 18 such websites that one could access via the Internet and that required only requiring user credentials to login into. Next, we searched for published policies on reporting vulnerabilities; we found no vulnerability-disclosure policies for any system we identified. To identify, prioritize, and address EAS vulnerabilities, we present a list of technical and management strategies to reduce cybersecurity threats. We recommend integrated policies and procedures at all levels of the public-private-government partnerships and system resilience as lines of defense against cybersecurity threats. By implementing these strategies, EASs in the US will be positioned to update critical infrastructure, notify groups of emergencies, and ensure the distribution of valid and reliable information to at-risk populations

Dynamical Processes in the Planet-Forming Environment

The transfer of circumstellar disk mass and momentum onto the protostar and out into the environment occurs via a variety of mechanisms including magnetospheric accretion, jets, outflows, and disk winds. The interplay of these processes determine both the conditions under which planet formation occurs and the lifetime of the disk. Metallic emission lines, along with the Balmer series of hydrogen, probe the kinematics of gas within the planet-forming and central regions of circumstellar disks. High-spectral resolution study of these emission lines provides critical information on mass and momentum loss, turbulence, and disk wind origins