Detection of Rotational Spectral Variation on the M-type asteroid (16) Psyche

The asteroid (16) Psyche is of scientific interest because it contains ~ 1% of the total mass of the asteroid belt and is thought to be the remnant metallic core of a protoplanet. Radar observations have indicated the significant presence of metal on the surface with a small percentage of silicates. Prior ground-based observations showed rotational variations in the near-infrared (NIR) spectra and radar albedo of this asteroid. However, no comprehensive study that combines multi-wavelength data has been conducted so far. Here we present rotationally resolved NIR spectra (0.7-2.5 microns) of (16) Psyche obtained with the NASA Infrared Telescope Facility. These data have been combined with shape models of the asteroid for each rotation phase. Spectral band parameters extracted from the NIR spectra show that the pyroxene band center varies from ~ 0.92 to 0.94 microns. Band center values were used to calculate the pyroxene chemistry of the asteroid, whose average value was found to be Fs30En65Wo5. Variations in the band depth were also observed, with values ranging from 1.0 to 1.5%. Using a new laboratory spectral calibration we estimated an average orthopyroxene content of 6+/-1%. The mass-deficit region of Psyche, which exhibits the highest radar albedo, also shows the highest value for spectral slope and the minimum band depth. The spectral characteristics of Psyche suggest that its parent body did not have the typical structure expected for a differentiated body or that the sequence of events that led to its current state was more complex than previously thought.Comment: 21 pages, 8 figures, 2 tables, published in The Astronomical Journa

Growth rate of binary words avoiding xxxRxxx^R

Consider the set of those binary words with no non-empty factors of the form $xxx^R$. Du, Mousavi, Schaeffer, and Shallit asked whether this set of words grows polynomially or exponentially with length. In this paper, we demonstrate the existence of upper and lower bounds on the number of such words of length $n$, where each of these bounds is asymptotically equivalent to a (different) function of the form $Cn^{\lg n+c}$, where $C$, $c$ are constants

Reconciliation through Description: Using Metadata to Realize the Vision of the National Research Centre for Truth and Reconciliation

PostprintThis articlewill discuss the history and context surrounding the document collection and statement gathering mandates of the Truth and Reconciliation Commission of Canada and the challenges the newly established National Research Centre for Truth and Reconciliation will face in applying the Commission’s metadata set in the realization of its vision. By working respectfully with Indigenous people through the implementation of Indigenous knowledge best practices and the application of contrasting traditional/nontraditional, archival/user-generated, and institutional/Indigenous descriptive elements, the Centre will attempt to create a “living archive” and facilitate Indigenous participation, collaboration, and ultimately, the process of reconciliation.https://www-tandfonline-com.uwinnipeg.idm.oclc.org/doi/full/10.1080/01639374.2015.100871

A new polymorph of phenylselenium trichloride

A second polymorph of phenylselenium trichloride, PhSeCl3 or C6H5Cl3Se, is disclosed, which is comprised of asymmetric chlorine-bridged noncovalent dimer units rather than polymeric chains. These dimers are each weakly bound to an adjacent dimer through noncovalent Se...Cl bonding interactions. Phenyl rings within each dimer are oriented in a syn fashion. Density functional theory (DFT) calculations reveal that the putative anti isomer is within 5 kJ mol-1 of the experimentally observed form. This structure represents the first additional polymorph discovered for an organoselenium trihalide compound.https://doi.org/10.1107/S205322961901301

Building the System: Follow-up, monitoring & adaptive management

Does impact assessment (IA) end when the license has been granted? While societal resources tend to focus on rigorous project approvals, what happens to the project, to the public and to the environment once approval is granted? Follow up and monitoring are often an afterthought for legislators, public servants and proponents. But they are critical to public confidence and to ensuring that proponents live up to their commitments in a rapidly changing world."This report draws from research funded by the Impact Assessment Agency as part of the Social Sciences and Humanities Research Council of Canada Knowledge Mobilization Grant on Informing Best Practice in Environmental and Impact Assessment.

A family of formulas with reversal of high avoidability index

We present an infinite family of formulas with reversal whose avoidability index is bounded between 4 and 5, and we show that several members of the family have avoidability index 5. This family is particularly interesting due to its size and the simple structure of its members. For each k ∈ {4,5}, there are several previously known avoidable formulas (without reversal) of avoidability index k, but they are small in number and they all have rather complex structure.http://dx.doi.org/10.1142/S021819671750024

The metric dimension and metric independence of a graph

A vertex x of a graph G resolves two vertices u and v of G if the distance from x to u does not equal the distance from x to v. A set S of vertices of G is a resolving set for G if every two distinct vertices of G are resolved by some vertex of S. The minimum cardinality of a resolving set for G is called the metric dimension of G. The problem of nding the metric dimension of a graph is formulated as an integer pro- gramming problem. It is shown how a relaxation of this problem leads to a linear programming problem and hence to a fractional version of the metric dimension of a graph. The linear programming dual of this problem is considered and the solution to the corresponding integer programming problem is called the metric independence of the graph. It is shown that the problem of deciding whether, for a given graph G, the metric dimension of G equals its metric independence is NP- complete. Trees with equal metric dimension and metric independence are characterized. The metric independence number is established for various classes of graphs.Preprin

On the Andrews congruence for the Fibonacci quotient

We show that a congruence discovered by George E. Andrews in 1969 for the Fibonacci quotient directly implies a simpler congruence found by Hugh C. Williams in 1991

Binary words avoiding xx^Rx and strongly unimodal sequences

In previous work, Currie and Rampersad showed that the growth of the number of binary words avoiding the pattern xxx^R was intermediate between polynomial and exponential. We now show that the same holds for the growth of the number of binary words avoiding the pattern xx^Rx. Curiously, the analysis for xx^Rx is much simpler than that for xxx^R. We derive our results by giving a bijection between the set of binary words avoiding xx^Rx and a class of sequences closely related to the class of "strongly unimodal sequences."Comment: 4 page