Surveillance, social punishment, and the viability of Homo Virtualis

As emerging encryption technology results in widespread freedom from detection of online activity, Homo Virtualis might usefully be considered as Homo sapiens without a gun to its head—a highly evolved species experiencing, for the first time on a massive scale, a home environment in which the individual who engages in acts that harm others is not identifiable. This renders the punishment of antisocial behavior in this context impossible, clearing the warning signals for retribution and crippling this ancient and brutal method for limiting the occurrence of antisocial or unwanted behavior. If Homo Virtualis is to retain this newfound freedom from threat and invigilation, prosocial behavior must continue to prevail in the absence of credible threat of punishment for the antisocial. The prospects are far from certain, and an attendant spike in the frequency of misdeed would be sure to evoke a crackdown on encryption tech. On the bright side, a widespread failure of punishment to inhibit malice and malfeasance online might finally evoke serious consideration of how H. sapiens might ensure a low frequency of antisocial behavior absent the threat of dire consequence for transgression, via the positive reinforcement of prosocial conduct, rendering interpersonal and community sensitivity and service pleasurable rather than obligatory. Encryption technologies can provide valuable support for such a comprehensively humanistic effort to reduce malfeasance by eliminating threats of public censure for current and budding offenders’ own efforts to address their problematic proclivities

The CIV-MgII Kinematics Connection in <z>~0.7 Galaxies

We have examined Faint Object Spectrograph data from the Hubble Space Telescope Archive for CIV 1548,1550 absorption associated with 40 MgII 2796,2803 absorption-selected galaxies at 0.4 < z < 1.4. We report a strong correlation between MgII kinematics, measured in 6 km/s resolution HIRES/Keck spectra, and W_r(1548); this implies a physical connection between the processes that produce "outlying velocity" MgII clouds and high ionization galactic/halo gas. We found no trend in ionization condition, W_r(1548)/W_r(2796), with galaxy-QSO line-of-sight separation for 13 systems with confirmed associated galaxies, suggesting no obvious ionization gradient with galactocentric distance in these higher redshift galaxies. We find tentative evidence (2-sigma) that W_r(1548)/W_r(2796) is anti-correlated with galaxy color; if further data corroborate this trend, in view of the strong CIV-MgII kinematics correlation, it could imply a connection between stellar populations, star formation episodes, and the kinematics and ionization conditions of halo gas at z~1.Comment: Accepted to Astrophysical Journal Letters; 4 pages; 3 figures; emulateapj.st

Detection of Circular Polarization in M81*

We report the detection of circular polarization in the compact radio jet of the nearby spiral galaxy M81 (M81*). The observations were made with the Very Large Array at 4.8 and 8.4 GHz and circular polarization was detected at both frequencies. We estimate a value of $m_{c}=0.54\pm0.06\pm0.07$ at 8.4 GHz and $m_{c}=0.27\pm0.06\pm0.07$ at 4.8 GHz for the fractional circular polarization. The errors are separated into statistical and systematic terms. The spectrum of the circular polarization is possibly inverted which would be unusual for AGN. We also detected no linear polarization in M81* at a level of 0.1% implying that the source has a very high circular-to-linear polarization ratio as found so far only in Sgr A*, the central radio source in our Galaxy. This further supports the idea that M81* is a scaled-up version of Sgr A* and suggests that the polarization properties are intrinsic to the two sources and are not caused by a foreground screen in the Galaxy.Comment: 9 pages, 1 figure, accepted for publication in ApJ Letter

Incorporating Ambipolar and Ohmic Diffusion in the AMR MHD code RAMSES

We have implemented non-ideal Magneto-Hydrodynamics (MHD) effects in the Adaptive Mesh Refinement (AMR) code RAMSES, namely ambipolar diffusion and Ohmic dissipation, as additional source terms in the ideal MHD equations. We describe in details how we have discretized these terms using the adaptive Cartesian mesh, and how the time step is diminished with respect to the ideal case, in order to perform a stable time integration. We have performed a large suite of test runs, featuring the Barenblatt diffusion test, the Ohmic diffusion test, the C-shock test and the Alfven wave test. For the latter, we have performed a careful truncation error analysis to estimate the magnitude of the numerical diffusion induced by our Godunov scheme, allowing us to estimate the spatial resolution that is required to address non-ideal MHD effects reliably. We show that our scheme is second-order accurate, and is therefore ideally suited to study non-ideal MHD effects in the context of star formation and molecular cloud dynamics

A Radio Survey for Linear and Circular Polarization in Low Luminosity Active Galactic Nuclei

We conducted a Very Large Array survey of eleven low luminosity active galactic nuclei for linear and circular polarization at 8.4 GHz. We detected circular polarization in one source (M81*) and linear polarization in 3 sources. Sensitivity limits were ~0.1% for both modes of polarization in 9 of 11 sources. The detections confirm the importance of nonthermal emission in LLAGN. However, detection rates for circular and linear polarization are lower for these sources than for more powerful AGN. Fractional linear polarization in detected sources is also lower than in more powerful AGN. The weak linear polarization in the survey sources indicates their overall similarity to Sgr A*. Confusion with thermal sources, depolarization and weaker, less extended jets may contribute to these differences. We detect a rotation measure >~ 7 x 10^4 rad m^-2 for NGC 4579. This may arise from magnetized plasma in the accretion, outflow or interstellar regions. Inverted spectra are present in both M81* and Sagittarius A* and absent from all sources in which circular polarization is not detected. This suggests that optical depth effects are important in the creation of circular polarization.Comment: 12 pages, 2 figures, accepted for publication in ApJ

North to south asymmetries in the water‐equivalent hydrogen distribution at high latitudes on Mars

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95381/1/jgre2434.pd

The clinical outcomes of cementless unicompartmental knee replacement in patients with reduced bone mineral density

Background: Osteoporosis and osteopenia are conditions characterised by reduced bone mineral density (BMD). There is concern that bone with reduced BMD may not provide sufficient fixation for cementless components which primarily rely on the quality of surrounding bone. The aim of our study was to report the midterm clinical outcomes of patients with reduced BMD undergoing cementless unicompartmental knee replacements (UKR). Our hypothesis was that there would be no difference in outcome between patients with normal bone and those with reduced BMD. Methods: From a prospective cohort of 70 patients undergoing cementless UKR surgery, patients were categorised into normal (n&thinsp;=&thinsp;20), osteopenic (n&thinsp;=&thinsp;38) and osteoporotic groups (n&thinsp;=&thinsp;12) based on their central dual-energy X-ray absorptiometry (DEXA) scans according to the World Health Organization criteria. Patients were followed up by independent research physiotherapists and outcome scores; Oxford Knee Score (OKS), Tegner score, American Knee Society Score Functional (AKSS-F) and Objective (AKSS-O) were recorded preoperatively and at a mean of 4&thinsp;years postoperatively. The prevalence of reoperations, revisions and mortality was also recorded at a mean of 5&thinsp;years postoperatively. Results: There were no significant differences in the midterm postoperative OKS (P&thinsp;=&thinsp;0.83), Tegner score (P&thinsp;=&thinsp;0.17) and AKSS-O (P&thinsp;=&thinsp;0.67). However, the AKSS-F was significantly higher (P&thinsp;=&thinsp;0.04) in normal (90, IQR 37.5) compared to osteoporotic (65, IQR 35) groups. There were no significant differences (P&thinsp;=&thinsp;0.82) between normal and osteopenic bone (80, IQR 35). The revision prevalence was 5%, 2.6% and 0% in the normal, osteopenic and osteoporotic groups respectively. The reoperation prevalence was 5%, 7.9% and 0% respectively. There were no deaths in any group related to the implant. Conclusions: We found that patients with reduced BMD could safely undergo cementless UKR surgery and have similar clinical outcomes to those with normal BMD. However, larger studies with longer follow-up are needed to confirm our findings and ensure that cementless fixation is safe in patients with reduced BMD.</p

The Spatial, Ionization, and Kinematic Conditions of the z=1.39 Damped Ly-alpha Absorber in Q0957+561 A,B

We examined the sizes of the absorption clouds in a z=1.3911 damped Ly-alpha absorber (DLA) in the double image lensed quasar Q0957+561 A,B (separation 135 pc at the absorber redshift). Using HIRES/Keck spectra, we studied the MgII 2796,2803 doublet, FeII multiplet, and MgI 2853 transition in absorption. We defined six "clouds" in the system of sightline A and seven clouds in the system of sightline B. An examination of the N(v) profiles, using the apparent optical depth method, reveals no clear physical connection between the clouds in A and those in B. The observed column density ratios of all clouds is log[N(MgI)/N(FeII)] ~ -2 across the full velocity range in both systems and also spatially (in both sightlines). This is a remarkable uniformity not seen in Lyman limit systems. The uniformity of the cloud properties suggests that the multiple clouds are not part of a "halo". Based upon photoionization modeling, we constrain the ionization parameters in the range -6.2 < log(U) < -5.1, where the range brackets known abundance ratio and dust depletion patterns. The inferred cloud properties are densities of 2 < n_H < 20 cm^-3, and line of sight sizes of 1 < D < 25 pc. The masses of the clouds in system A are 10 < M/M_sun < 1000 and in system B are 1 < M/M_sun < 60 for spherical clouds. For planar clouds, the upper limits are 400 M_sun and 160 M_sun for A and B, respectively. We favor a model of the absorber in which the DLA region itself is a single cloud in thiscomplex, which could be a parcel of gas in a galactic ISM. A spherical cloud of ~10 pc would be limited to one of the sightlines (A) and imply a covering factor less than 0.1 for the DLA complex. We infer that the DLA cloud properties are consistent with those of lower density, cold clouds in the Galactic interstellar medium.Comment: Accepted for publication in the Astrophysical Journal; final versio