Deuterium Chemodynamics of Massive Pre-Stellar Cores

High levels of deuterium fractionation of $\rm N_2H^+$ (i.e., $\rm D_{frac}^{N_2H^+} \gtrsim 0.1$) are often observed in pre-stellar cores (PSCs) and detection of $\rm N_2D^+$ is a promising method to identify elusive massive PSCs. However, the physical and chemical conditions required to reach such high levels of deuteration are still uncertain, as is the diagnostic utility of $\rm N_2H^+$ and $\rm N_2D^+$ observations of PSCs. We perform 3D magnetohydrodynamics simulations of a massive, turbulent, magnetised PSC, coupled with a sophisticated deuteration astrochemical network. Although the core has some magnetic/turbulent support, it collapses under gravity in about one freefall time, which marks the end of the simulations. Our fiducial model achieves relatively low $\rm D_{frac}^{N_2H^+} \sim 0.002$ during this time. We then investigate effects of initial ortho-para ratio of $\rm H_2$ ($\rm OPR^{H_2}$), temperature, cosmic ray (CR) ionization rate, CO and N-species depletion factors and prior PSC chemical evolution. We find that high CR ionization rates and high depletion factors allow the simulated $\rm D_{frac}^{N_2H^+}$ and absolute abundances to match observational values within one freefall time. For $\rm OPR^{H_2}$, while a lower initial value helps the growth of $\rm D_{frac}^{N_2H^+}$, the spatial structure of deuteration is too widespread compared to observed systems. For an example model with elevated CR ionization rates and significant heavy element depletion, we then study the kinematic and dynamic properties of the core as traced by its $\rm N_2D^+$ emission. The core, undergoing quite rapid collapse, exhibits disturbed kinematics in its average velocity map. Still, because of magnetic support, the core often appears kinematically sub-virial based on its $\rm N_2D^+$ velocity dispersion.Comment: 25 pages, 20 figures, 2 tables, accepted for publication in MNRAS, comments welcom

Code Comparison in Galaxy Scale Simulations with Resolved Supernova Feedback: Lagrangian vs. Eulerian Methods

We present a suite of high-resolution simulations of an isolated dwarf galaxy using four different hydrodynamical codes: {\sc Gizmo}, {\sc Arepo}, {\sc Gadget}, and {\sc Ramses}. All codes adopt the same physical model which includes radiative cooling, photoelectric heating, star formation, and supernova (SN) feedback. Individual SN explosions are directly resolved without resorting to sub-grid models, eliminating one of the major uncertainties in cosmological simulations. We find reasonable agreement on the time-averaged star formation rates as well as the joint density-temperature distributions between all codes. However, the Lagrangian codes show significantly burstier star formation, larger supernova-driven bubbles, and stronger galactic outflows compared to the Eulerian code. This is caused by the behavior in the dense, collapsing gas clouds when the Jeans length becomes unresolved: gas in Lagrangian codes collapses to much higher densities than in Eulerian codes, as the latter is stabilized by the minimal cell size. Therefore, more of the gas cloud is converted to stars and SNe are much more clustered in the Lagrangian models, amplifying their dynamical impact. The differences between Lagrangian and Eulerian codes can be reduced by adopting a higher star formation efficiency in Eulerian codes, which significantly enhances SN clustering in the latter. Adopting a zero SN delay time reduces burstiness in all codes, resulting in vanishing outflows as SN clustering is suppressed.Comment: accepted version by ApJ (including a new simulation in Appendix B suggested by the referee

Engineering Phonon-Qubit Interactions using Phononic Crystals

The ability to control phonons in solids is key for diverse quantum applications, ranging from quantum information processing to sensing. Often, phonons are sources of noise and decoherence, since they can interact with a variety of solid-state quantum systems. To mitigate this, quantum systems typically operate at milli-Kelvin temperatures to reduce the number of thermal phonons. Here we demonstrate an alternative approach that relies on engineering phononic density of states, drawing inspiration from photonic bandgap structures that have been used to control the spontaneous emission of quantum emitters. We design and fabricate diamond phononic crystals with a complete phononic bandgap spanning 50 - 70 gigahertz, tailored to suppress interactions of a single silicon-vacancy color center with resonant phonons of the thermal bath. At 4 Kelvin, we demonstrate a reduction of the phonon-induced orbital relaxation rate of the color center by a factor of 18 compared to bulk. Furthermore, we show that the phononic bandgap can efficiently suppress phonon-color center interactions up to 20 Kelvin. In addition to enabling operation of quantum memories at higher temperatures, the ability to engineer qubit-phonon interactions may enable new functionalities for quantum science and technology, where phonons are used as carriers of quantum information

The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey : measuring DA and H at z = 0.57 from the baryon acoustic peak in the Data Release 9 spectroscopic Galaxy sample

We present measurements of the angular diameter distance to and Hubble parameter at z = 0.57 from the measurement of the baryon acoustic peak in the correlation of galaxies from the Sloan Digital Sky Survey III Baryon Oscillation Spectroscopic Survey. Our analysis is based on a sample from Data Release 9 of 264 283 galaxies over 3275 square degrees in the redshift range 0.43 < z < 0.70. We use two different methods to provide robust measurement of the acoustic peak position across and along the line of sight in order to measure the cosmological distance scale. We find DA(0.57) = 1408 ± 45 Mpc and H(0.57) = 92.9 ± 7.8 km s−1 Mpc−1 for our fiducial value of the sound horizon. These results from the anisotropic fitting are fully consistent with the analysis of the spherically averaged acoustic peak position presented in Anderson et al. Our distance measurements are a close match to the predictions of the standard cosmological model featuring a cosmological constant and zero spatial curvature.Publisher PDFPeer reviewe

Genetic risk variants for social anxiety

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136300/1/ajmgb32520.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136300/2/ajmgb32520_am.pd

Genomeâ wide analyses of psychological resilience in U.S. Army soldiers

Though a growing body of preclinical and translational research is illuminating a biological basis for resilience to stress, little is known about the genetic basis of psychological resilience in humans. We conducted genomeâ wide association studies (GWASs) of selfâ assessed (by questionnaire) and outcomeâ based (incident mental disorders from predeployment to postdeployment) resilience among European (EUR) ancestry soldiers in the Army study to assess risk and resilience in servicemembers. Selfâ assessed resilience (Nâ =â 11,492) was found to have significant commonâ variant heritability (h2 =â 0.162, seâ =â 0.050, pâ =â 5.37â Ã â 10â 4), and to be significantly negatively genetically correlated with neuroticism (rgâ =â â 0.388, pâ =â .0092). GWAS results from the EUR soldiers revealed a genomeâ wide significant locus on an intergenic region on Chr 4 upstream from doublecortinâ like kinase 2 (DCLK2) (four single nucleotide polymorphisms (SNPs) in LD; top SNP: rs4260523 [pâ =â 5.65â Ã â 10â 9] is an eQTL in frontal cortex), a member of the doublecortin family of kinases that promote survival and regeneration of injured neurons. A second gene, kelchâ like family member 36 (KLHL36) was detected at geneâ wise genomeâ wide significance [pâ =â 1.89â Ã â 10â 6]. A polygenic risk score derived from the selfâ assessed resilience GWAS was not significantly associated with outcomeâ based resilience. In very preliminary results, genomeâ wide significant association with outcomeâ based resilience was found for one locus (top SNP: rs12580015 [pâ =â 2.37â Ã â 10â 8]) on Chr 12 downstream from solute carrier family 15 member 5 (SLC15A5) in subjects (Nâ = 581) exposed to the highest level of deployment stress. The further study of genetic determinants of resilience has the potential to illuminate the molecular bases of stressâ related psychopathology and point to new avenues for therapeutic intervention.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/149528/1/ajmgb32730.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149528/2/ajmgb32730_am.pd

Genomewide association studies of suicide attempts in US soldiers

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/139960/1/ajmgb32594.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/139960/2/ajmgb32594_am.pd