This is What it Means to be a DACA Recipient

Since 2012, over 800,000 DREAMers, like ourselves, have been given the legal right to work, apply for a driver’s license, and, most importantly, live without the fear of deportation. We complete background checks and pay $495 in fees every two years to maintain our DACA (Deferred Action for Childhood Arrivals) status. [excerpt

Empirical Fit to Inelastic Electron-Deuteron and Electron-Neutron Resonance Region Transverse Cross Sections

An empirical fit is described to measurements of inclusive inelastic electron-deuteron cross sections in the kinematic r ange of four-momentum transfer $0 \le Q^2<10$ GeV$^2$ and final state invariant mass $1.1<W<3.2$ GeV. The deuteron fit relies on a fit of the ratio $R_p$ of longitudinal to transverse cross sections for the proton, and the assumption $R_p=R_n$. The underlying fit parameters describe the average cross section for proton and neutron, with a plane-wave impulse approximation used to fit to the deuteron data. An additional term is used to fill in the dip between the quasi-elastic peak and the $\Delta(1232)$ resonance. The mean deviation of data from the fit is 3%, with less than 4% of the data points deviating from the fit by more than 10%.Comment: 16 pages, 5 figures, submitted to Phys. Rev. C. Text clarified in response to referee comment

Inviscid helical magnetorotational instability in cylindrical Taylor-Couette flow

This paper presents the analysis of axisymmetric helical magnetorotational instability (HMRI) in the inviscid limit, which is relevant for astrophysical conditions. The inductionless approximation defined by zero magnetic Prandtl number is adopted to distinguish the HMRI from the standard MRI in the cylindrical Taylor-Couette flow subject to a helical magnetic field. Using a Chebyshev collocation method convective and absolute instability thresholds are computed in terms of the Elsasser number for a fixed ratio of inner and outer radii \lambda=2 and various ratios of rotation rates and helicities of the magnetic field. It is found that the extension of self-sustained HMRI modes beyond the Rayleigh limit does not reach the astrophysically relevant Keplerian rotation profile not only in the narrow- but also in the finite-gap approximation. The Keppler limit can be attained only by the convective HMRI mode provided that the boundaries are perfectly conducting. However, this mode requires not only a permanent external excitation to be observable but also has a long axial wave length, which is not compatible with limited thickness of astrophysical accretion disks.Comment: 12 pages, 9 figures, published version with a few typos correcte