First measurement and shell model interpretation of the g factor of the 21+ state in self-conjugate radioactive 44Ti

AbstractThe g factor of the 21+ state in radioactive 44Ti has been measured for the first time with the technique of α transfer to 40Ca beams in inverse kinematics in combination with transient magnetic fields, yielding the value, g(21+)=+0.52(15). In addition, the lifetimes of the 21+, τ=3.97(28) ps, and the 41+ states, τ=0.65(6) ps, were redetermined with higher precision using the Doppler shift attenuation method. The deduced B(E2)'s and the g factor were well explained by a full fp shell model calculation using the FPD6 effective NN interaction. The g factor can also be accounted for by a simple rotational model (g=Z/A). However, if one also considers the B(E2)'s and the E(41+)/E(21+) ratios, then an imperfect vibrator picture gives better agreement with the data

PRIORITIZING PARCELS FOR CONSERVATION EASEMENTS USING LEAST-COST PATH ANALYSES OF LAND OWNERSHIP: CASE STUDY WITHIN THEORIZED GRIZZLY BEAR MIGRATION CORRIDORS OF WESTERN MONTANA

As the world’s human population has grown and converted large natural habitats to human dominated landscapes, the planet’s biodiversity has decreased. To combat the loss of biodiversity from human development, many conservation professionals champion the concept of conservation corridors between intact habitats. Conservation corridors, made up of protected land, serve as a connection for wildlife populations to intermix genetics and, subsequently, help reduce the risk of extinction. The ideal geographic location of corridors is generally determined through geographic information system modeling using biophysical conditions and theorized animal movement. However, the resulting corridors are often expansive and protecting entire corridors is usually impossible. Therefore, determining where conservation actions, such as placing a conservation easement on a private parcel, have the most opportunity for connecting landscapes is key to maximizing benefits with limited resources. This study examines how public land can be considered as protected habitat, due to federal mandates, and serve as a facilitating factor for establishing conservation corridors with conservation easements on private parcels. It utilizes least cost pathway analyses within theorized grizzly bear migration corridors of western Montana to show the potential for conservation easements to provide connectivity of protected lands within conservation corridors. The case study compares differing cost values for varying land ownership types to aid in corridor implementation planning. From the analysis, the resulting least cost pathways show promise for identifying individual private parcels, and therefore specific areas, within the larger wildlife corridor for concentrated conservation action. The approach shows promise for land trusts and other organizations working to place conservation easements on parcels with the highest conservation opportunity to connect large intact landscapes

HI Narrow Self-Absorption in Dark Clouds: Correlations with Molecular Gas and Implications for Cloud Evolution and Star Formation

We present the results of a comparative study of HI narrow self-absorption (HINSA), OH, 13CO, and C18O in five dark clouds. The HINSA follows the distribution of the emission of the carbon monoxide isotopologues, and has a characteristic size close to that of 13CO. This confirms that the HINSA is produced by cold HI which is well mixed with molecular gas in well-shielded regions. The ratio of the atomic hydrogen density to total proton density for these sources is 5 to 27 x 10^{-4}. Using cloud temperatures and the density of HI, we set an upper limit to the cosmic ray ionization rate of 10^{-16} s^{-1}. Comparison of observed and modeled fractional HI abundances indicates ages for these clouds to be 10^{6.5} to 10^{7} yr. The low values of the HI density we have determined make it certain that the time scale for evolution from an atomic to an almost entirely molecular phase, must be a minimum of several million years. This clearly sets a lower limit to the overall time scale for star formation and the lifetime of molecular clouds

An atomic and molecular database for analysis of submillimetre line observations

Atomic and molecular data for the transitions of a number of astrophysically interesting species are summarized, including energy levels, statistical weights, Einstein A-coefficients and collisional rate coefficients. Available collisional data from quantum chemical calculations and experiments are extrapolated to higher energies. These data, which are made publically available through the WWW at http://www.strw.leidenuniv.nl/~moldata, are essential input for non-LTE line radiative transfer programs. An online version of a computer program for performing statistical equilibrium calculations is also made available as part of the database. Comparisons of calculated emission lines using different sets of collisional rate coefficients are presented. This database should form an important tool in analyzing observations from current and future (sub)millimetre and infrared telescopes.Comment: Accepted for publication in A&A, 14 pages, 5 figure

Discovery of interstellar mercapto radicals (SH) with the GREAT instrument on SOFIA

We report the first detection of interstellar mercapto radicals, obtained along the sight-line to the submillimeter continuum source W49N. We have used the GREAT instrument on SOFIA to observe the 1383 GHz Doublet Pi 3/2 J = 5/2 - 3/2 lambda doublet in the upper sideband of the L1 receiver. The resultant spectrum reveals SH absorption in material local to W49N, as well as in foreground gas, unassociated with W49N, that is located along the sight-line. For the foreground material at velocities in the range 37 - 44 km/s with respect to the local standard of rest, we infer a total SH column density ~ 2.6 E+12 cm-2, corresponding to an abundance of ~ 7 E-9 relative to H2, and yielding an SH/H2S abundance ratio ~ 0.13. The observed SH/H2S abundance ratio is much smaller than that predicted by standard models for the production of SH and H2S in turbulent dissipation regions and shocks, and suggests that the endothermic neutral-neutral reaction SH + H2 -> H2S + H must be enhanced along with the ion-neutral reactions believed to produce CH+ and SH+ in diffuse molecular clouds.Comment: Accepted for publication in Astronomy and Astrophysics (SOFIA/GREAT special issue

Molecular excitation in the Interstellar Medium: recent advances in collisional, radiative and chemical processes

We review the different excitation processes in the interstellar mediumComment: Accepted in Chem. Re

A blot on the landscape? Civic memory and municipal public parks in early twentieth century Manchester

This paper examines the decision to locate the façade of Manchester’s old Town Hall in a public park (Heaton Park) in 1912. It argues that, in so doing, the city’s Parks and Cemeteries committee was attempting to refine the didactic space of the park as a site of civic memory. The early Victorian urban parks had sought to educate their visitors through their museums, art galleries and exhibition spaces, glasshouses and carefully-planned and planted walkways. The insertion into this environment of part of a former civic building was intended to remind the visitors of their civic history and to warn surrounding districts of the expansionist tendencies of the city of Manchester. The failure to identify the façade or to connect it to its surroundings meant that its meaning was ultimately lost to many parks visitors and it remained in place as a civic folly. Public parks presented the municipal authorities with an opportunity to highlight the provision of recreation and leisure facilities, but also an occasion to re-invent the municipal tradition. However, as this paper shows, such gestures were often futile in the complex and contested space of the public park

Insights into the role of silicon and graphite in the electrochemical performance of silicon/graphite blended electrodes with a multi-material porous electrode model

Silicon/graphite blended electrodes are promising candidates to replace graphite in lithium ion batteries, benefiting from the high capacity of silicon and the good structural stability of carbon. Models have proven essential to understand and optimise batteries with new materials. However, most previous models treat silicon/graphite blends as a single “lumped” material, offering limited understanding of the behaviors of the individual materials and thus limited design capability. Here, we present a multi-material model for silicon/graphite electrodes with detailed descriptions of the contributions of the individual active materials. The model shows that silicon introduces voltage hysteresis to silicon/graphite electrodes and consequently a “plateau shift” during delithiation of the electrodes. There will also be competition between the silicon and graphite lithiation reactions depending on silicon/graphite ratio. A dimensionless competing factor is derived to quantify the competition between the two active materials. This is demonstrated to be a useful indicator for active operating regions for each material and we demonstrate how it can be used to design cycling protocols for mitigating electrode degradation. The multi-material electrode model can be readily implemented into full-cell models and coupled with other physics to guide further development of lithium ion batteries with silicon-based electrodes

Regularized MPC for power management of hybrid energy storage systems with applications in electric vehicles

This paper examines the application of Regularized Model Predictive Control (RMPC) for Power Management (PM) of Hybrid Energy Storage Systems (HESSs). To illustrate, we apply the idea to the PM problem of a battery-supercapacitors (SCs) powertrain to reduce battery degradation in Electric Vehicles (EVs). While the application of Quadratic MPC (QMPC) in PM of HESS is not new, the idea to examine RMPC here is motivated by its capabilities to prioritize actuator actions and efficiently allocate control effort, as advocated by recent works in the control and MPC literature. Thorough simulations have been run over standard urban test drive cycles. It is found out that QMPC and RMPC, compared to rule-based PM strategies, could reduce the battery degradation over 70%. It is also shown that RMPC can slightly outperform QMPC in reducing battery degradation. Moreover, RMPC, compared to QMPC, could potentially extend the range of that SCs can be used, thus exploiting the degree of freedom of the powertrain to a larger extent. We also make some discussions on the feasibility issues and tuning challenges that RMPC faces, among others