HISCAT: A proposed new scatter facility in Northern Scandinavia

It is proposed that a new versatile ionospheric and atmospheric scatter radar be constructed in northern Scandavia through a multinational collaborative effort. The new facility tentatively named HISCAT (High frequency, High power, High latitude, Heating and Ionospheric Scatter facility), should be used for scientific investigations of: the physics of the neutral (middle) atmosphere; fundamental plasma phenomena, natural or artificially induced in the ionosphere; electrodynamic conditions at high altitudes above the auroral region and in the polar cap ionosphere; plasma waves in the solar atmosphere. The system should thus be able to operate as a mesosphere-stratosphere-troposphere (MST) radar, a so-called ionospheric modification facility, incoherent-scatter radar, coherent-scatter radar, and solar radar. Basically, the new facility should be a device that can operate simultaneously on several frequencies in the frequency range 5 to 50 MHz not covered by other instruments. It should comprise: powerful transmitters, capable of delivering a total average power of several megawatts; an advanced phased antenna array of high gain forming one or two steerable and well collimated beams; and an advanced data collection and analysis system

Characterization of iodine particles with Volatilization-Humidification Tandem Differential Mobility Analyser (VH-TDMA), Raman and SEM techniques

Particles formed upon photo-oxidation of CH2I2 and particles of I2O5 and HIO3 have been studied using a Volatilisation and Humidification Tandem Differential Mobility Analyser (VH-TDMA) system. Volatilization and hygroscopic behaviour have been investigated as function of temperature (from 25 to 400 degrees Celsius), humidity (RH from 80 to 98%), initial aerosol sizes (from 27 to 100 nm mobility diameter) and in nitrogen or air as the sheath gasses. The volatility behaviour of particles formed upon photo-oxidation of CH2I2 is more similar to that of HIO3 particles in a filtered sheath air than in nitrogen, with the particle shrinkage occurring at 190 degrees Celsius and accompanied by hygroscopic growth. Despite its high solubility, HIO3 was found not to be hygroscopic at room temperature with no significant growth displayed until the thermodenuder temperature reached 200 degrees Celsius or above when the particles have transformed into I2O5. Diiodopentaoxide (I2O5) particles exhibit relatively low hygroscopic growth factors of 1.2-2 in the humidity range investigated. Scanning Electron Microscopy (SEM) of particles formed upon photo-oxidation of CH2I2 shows that their primary elemental components were iodine and oxygen in a stoichiometric ratio of approximately 1:2 with 10% error. Both Raman spectra and SEM show poor crystallinity for all the aerosols produced

Relativistic Disk Reflection in the Neutron Star X-ray Binary XTE J1709-267 with NuSTAR

We perform the first reflection study of the soft X-ray transient and Type 1 burst source XTE J1709-267 using NuSTAR observations during its 2016 June outburst. There was an increase in flux near the end of the observations, which corresponds to an increase from $\sim$0.04 L$_{\mathrm{Edd}}$ to $\sim$0.06 L$_{\mathrm{Edd}}$ assuming a distance of 8.5 kpc. We have separately examined spectra from the low and high flux intervals, which were soft and show evidence of a broad Fe K line. Fits to these intervals with relativistic disk reflection models have revealed an inner disk radius of $13.8_{-1.8}^{+3.0}\ R_{g}$ (where $R_{g} = GM/c^{2}$) for the low flux spectrum and $23.4_{-5.4}^{+15.6}\ R_{g}$ for the high flux spectrum at the 90\% confidence level. The disk is likely truncated by a boundary layer surrounding the neutron star or the magnetosphere. Based on the measured luminosity and using the accretion efficiency for a disk around a neutron star, we estimate that the theoretically expected size for the boundary layer would be $\sim0.9-1.1 \ R_{g}$ from the neutron star's surface, which can be increased by spin or viscosity effects. Another plausible scenario is that the disk could be truncated by the magnetosphere. We place a conservative upper limit on the strength of the magnetic field at the poles, assuming $a_{*}=0$ and $M_{NS}=1.4\ M_{\odot}$, of $B\leq0.75-3.70\times10^{9}$ G, though X-ray pulsations have not been detected from this source.Comment: Accepted for publication in ApJ, 5 pages, 4 figures, 1 table. arXiv admin note: text overlap with arXiv:1701.0177

Prediction and explanation in the multiverse

Probabilities in the multiverse can be calculated by assuming that we are typical representatives in a given reference class. But is this class well defined? What should be included in the ensemble in which we are supposed to be typical? There is a widespread belief that this question is inherently vague, and that there are various possible choices for the types of reference objects which should be counted in. Here we argue that the ``ideal'' reference class (for the purpose of making predictions) can be defined unambiguously in a rather precise way, as the set of all observers with identical information content. When the observers in a given class perform an experiment, the class branches into subclasses who learn different information from the outcome of that experiment. The probabilities for the different outcomes are defined as the relative numbers of observers in each subclass. For practical purposes, wider reference classes can be used, where we trace over all information which is uncorrelated to the outcome of the experiment, or whose correlation with it is beyond our current understanding. We argue that, once we have gathered all practically available evidence, the optimal strategy for making predictions is to consider ourselves typical in any reference class we belong to, unless we have evidence to the contrary. In the latter case, the class must be correspondingly narrowed.Comment: Minor clarifications adde

Spatial Regulation of Air Toxics Hot Spots

This paper analyzes the potential implications, in terms of net social costs and distribution of risks and abatement costs, of a policy to address the problem of air toxics “hot spots.” The policy we analyze involves regulation of air toxics sources at increasingly finer spatial resolutions. We develop a model of a decisionmaker choosing emission standards within a net cost minimization framework. Empirical application of the model to two counties in Florida demonstrates that regulation at finer resolutions could involve trade-offs between net social costs and equitable distribution of risks and, in some settings, between individual and population risks

Hot Spots Regulation and Environmental Justice

This paper analyzes whether regulating “hot spots” of toxic air pollution by increasing the spatial resolution of regulation could address environmental justice (EJ) concerns. To examine this question, this paper develops a decision model of a regulator choosing emission controls within a net cost minimizing framework. An empirical application of the model using air toxic emission data for Escambia and Santa Rosa Counties in Florida estimates the emission standards and spatial distribution of risks at a coarse and a finer spatial resolutions. Implications for EJ are analyzed by combining the simulated spatial risk distributions at the two resolutions with the demographic data. Results indicate that different measures of EJ point to different conclusions regarding the question of whether finer resolution regulation alleviates EJ concerns. The paper concludes with a discussion of the implications for EJ policy

Community Type in Context: Expectations of Guardianship and Victimization Experiences on a College Campus

The principles of guardianship can be traced through the communities and crime literature. While guardianship originates from the opportunities’ perspective and specifically from Routine Activities, it can be viewed as informal social controls at the community level. This study examines the impact of community type on expectations for guardianship. It also investigates the potential impact of these guardianship expectations on victimization on a college campus. This study uses original survey data. The sampling method consisted of two stages. In the first stage, courses were randomly selected for inclusion in the sample. In the second stage, the survey was made available to students in the learning management system course page with the consent of the instructor. The students completed a separate consent form. Data was collected in two waves in March/April and June/July of 2020. The final sample was 766 undergraduate students from a midsized southern university. The student response rate was 53% for both waves of data collection. This is a strong response rate for an online survey with data collection occurring during the beginning of the COVID-19 pandemic. Community type does influence expected guardianship with respondents from extremely rural communities having significantly lower expectations of guardianship than respondents from large urban cities. Expected guardianship does not significantly impact the odds of on-campus victimization. Exposure does not mediate this relationship although respondents with higher expected guardianship have significantly reduced exposure. Finally, neither fear of crime on campus nor just world belief significantly moderated the relationship between expected guardianship and victimization

Anthropic reasoning in multiverse cosmology and string theory

Anthropic arguments in multiverse cosmology and string theory rely on the weak anthropic principle (WAP). We show that the principle, though ultimately a tautology, is nevertheless ambiguous. It can be reformulated in one of two unambiguous ways, which we refer to as WAP_1 and WAP_2. We show that WAP_2, the version most commonly used in anthropic reasoning, makes no physical predictions unless supplemented by a further assumption of "typicality", and we argue that this assumption is both misguided and unjustified. WAP_1, however, requires no such supplementation; it directly implies that any theory that assigns a non-zero probability to our universe predicts that we will observe our universe with probability one. We argue, therefore, that WAP_1 is preferable, and note that it has the benefit of avoiding the inductive overreach characteristic of much anthropic reasoning.Comment: 7 pages. Expanded discussion of selection effects and some minor clarifications, as publishe

An Infrared Divergence Problem in the cosmological measure theory and the anthropic reasoning

An anthropic principle has made it possible to answer the difficult question of why the observable value of cosmological constant ($\Lambda\sim 10^{-47}$ GeV${}^4$) is so disconcertingly tiny compared to predicted value of vacuum energy density $\rho_{SUSY}\sim 10^{12}$ GeV${}^4$. Unfortunately, there is a darker side to this argument, as it consequently leads to another absurd prediction: that the probability to observe the value $\Lambda=0$ for randomly selected observer exactly equals to 1. We'll call this controversy an infrared divergence problem. It is shown that the IRD prediction can be avoided with the help of a Linde-Vanchurin {\em singular runaway measure} coupled with the calculation of relative Bayesian probabilities by the means of the {\em doomsday argument}. Moreover, it is shown that while the IRD problem occurs for the {\em prediction stage} of value of $\Lambda$, it disappears at the {\em explanatory stage} when $\Lambda$ has already been measured by the observer.Comment: 9 pages, RevTe