Using spin to understand the formation of LIGO's black holes

With the detection of four candidate binary black hole (BBH) mergers by the Advanced LIGO detectors thus far, it is becoming possible to constrain the properties of the BBH merger population in order to better understand the formation of these systems. Black hole (BH) spin orientations are one of the cleanest discriminators of formation history, with BHs in dynamically formed binaries in dense stellar environments expected to have spins distributed isotropically, in contrast to isolated populations where stellar evolution is expected to induce BH spins preferentially aligned with the orbital angular momentum. In this work we propose a simple, model-agnostic approach to characterizing the spin properties of LIGO's BBH population. Using measurements of the effective spin of the binaries, which is LIGO's best constrained spin parameter, we introduce a simple parameter to quantify the fraction of the population that is isotropically distributed, regardless of the spin magnitude distribution of the population. Once the orientation characteristics of the population have been determined, we show how measurements of effective spin can be used to directly constrain the underlying BH spin magnitude distribution. Although we find that the majority of the current effective spin measurements are too small to be informative, with LIGO's four BBH candidates we find a slight preference for an underlying population with aligned spins over one with isotropic spins (with an odds ratio of 1.1). We argue that it will be possible to distinguish symmetric and anti-symmetric populations at high confidence with tens of additional detections, although mixed populations may take significantly more detections to disentangle. We also derive preliminary spin magnitude distributions for LIGO's black holes, under the assumption of aligned or isotropic populations

Integrated doses for the different measurement positions and tube voltage.

<p>There were statistically significant differences (* p < 0.0001) as determined by two-way ANOVA between the main effects (measurement positions and tube voltage) for each fluoroscopic time. Error bars depict standard error of triplicates. A: Primary X-ray beam. B: Scatter radiation.</p

Dose profiles of CT fluoroscopy performed using optically stimulated luminescence dosimeters.

<p>A: Top. B: Lateral side. Each data point corresponds to the mean value of triplicate measurements.</p

Measuring positions used for optically stimulated luminescence dosimeters.

<p>A: Computed tomography image of the chest phantom at the center position during fluoroscopy; T, the position of optically stimulated luminescence (OSL) dosimeters on the top of the chest phantom; L, the position of OSL dosimeters on the lateral side of the chest phantom. B: Photograph of a measurement on the top of the chest phantom.</p

Integrated dose ratio for the measurement positions (IDR_P) with optically stimulated luminescence dosimetry.

<p>The IDR_P is the ratio of integrated dose that measured each tube voltage on the top to that on the lateral side of the chest phantom.</p><p>^aIDR_P in primary X-ray beam width along the z-axis at the chest phantom.</p><p>^bIDR_P of the dose profile tails caused by scatter radiation distribution (outside of the primary X-ray beam width) along the z-axis of the chest phantom.</p><p>Integrated dose ratio for the measurement positions (IDR_P) with optically stimulated luminescence dosimetry.</p

Integrated dose ratio for the tube voltage (IDR_V) determined by optically stimulated luminescence (OSL) dosimetry.

<p>The IDR_V is the ratio of the integrated dose measured at each position of the chest phantom at 80 kVp to that at 120 kVp.</p><p>^aIDR_V of the primary X-ray beam width along the z-axis of the chest phantom.</p><p>^bIDR_V of the dose profile tails caused by scatter radiation distribution (outside of the primary X-ray beam width) along the z-axis of the chest phantom.</p><p>Integrated dose ratio for the tube voltage (IDR_V) determined by optically stimulated luminescence (OSL) dosimetry.</p

Enzymatic Synthesis of Oligo(ethylene glycol)-Bearing Cellulose Oligomers for in Situ Formation of Hydrogels with Crystalline Nanoribbon Network Structures

Enzymatic synthesis of cellulose and its derivatives has gained considerable attention for use in the production of artificial crystalline nanocelluloses with unique structural and functional properties. However, the poor colloidal stability of the nanocelluloses during enzymatic synthesis in aqueous solutions limits their crystallization-based self-assembly to greater architectures. In this study, oligo­(ethylene glycol) (OEG)-bearing cellulose oligomers with different OEG chain lengths were systematically synthesized via cellodextrin phosphorylase-catalyzed oligomerization of α-d-glucose l-phosphate monomers against OEG-bearing β-d-glucose primers. The products were self-assembled into extremely well-grown crystalline nanoribbon network structures with the cellulose II allomorph, potentially due to OEG-derived colloidal stability of the nanoribbon’s precursors, followed by the in situ formation of physically cross-linked hydrogels. The monomer conversions, average degree of polymerization, and morphologies of the nanoribbons changed significantly, depending on the OEG chain length. Taken together, our findings open a new avenue for the enzymatic reaction-based facile production of novel cellulosic soft materials with regular nanostructures

Species richness of the understory woody vegetation in Japanese cedar plantations declines with increasing number of rotations

<p>The possibility of restoring natural broadleaf forests may be decreased by the effects of plantation management, particularly in sites that undergo repeated rotation. We investigated the following two working hypotheses about the effects of repeated plantation of conifers on the natural regeneration of woody saplings in cool-temperate Japanese cedar plantations: (1) that repeated plantation of conifers decreases sapling species richness, and (2) that repeated plantation of conifers changes sapling species compositions. Our result supported the first hypothesis, because species richness was significantly lower in second-rotation plantations than in first-rotation plantations. The second hypothesis was not supported, because no significant or substantial differences in species composition were observed between plantations with different numbers of rotations. However, the abundance of tree (nonshrub) and gravity-dispersed species decreased after the second rotation of large saplings, albeit not those of small saplings, suggesting that response to repeated rotation depended on sapling size. Our results suggest that it is important to consider factors affecting the maintenance of a species in the plantations, such as distance from natural forests and seed sources, to minimize the effects of repeated plantation.</p

Cellodextrin Phosphorylase-Catalyzed Single-Process Production and Superior Mechanical Properties of Organic–Inorganic Hybrid Hydrogels Composed of Surface-Carboxylated Synthetic Nanocelluloses and Hydroxyapatite

Artificial organic–inorganic hybrid materials produced through mineralization in/on biomolecular assemblies under aqueous-based mild conditions have attracted much attention due to the sustainability derived from environmentally friendly and low-energy production processes and excellent mechanical properties resulting from their highly organized structures. In this study, organic–inorganic hybrid hydrogels composed of crystalline nanoribbon assemblies of terminally carboxylated cellulose oligomers and hydroxyapatite (HAp) were produced via cellodextrin phosphorylase-catalyzed syntheses of the oligomers and in situ HAp mineralization achieved by combining phosphate ions kinetically fed by the enzyme reaction with coexisting calcium ions. Chemical structure characterizations revealed successful syntheses of the oligomers from the appropriate substrates (namely, monomers and primers). Crystallographic characterizations revealed that the cellulose moieties crystallized as the cellulose II allomorph, thereby leading to an antiparallel molecular arrangement in the assemblies, and that the calcium phosphate produced was assignable to HAp. Microscopic observations revealed the production of surface-carboxylated nanoribbon assemblies of the oligomers onto which HAp granules were hybridized, while the hybrid structure was not observed for nanoribbon assemblies of plain cellulose oligomers even after HAp mineralization. Mechanical property characterizations revealed that the stiffness (namely, Young’s modulus) of the hybrid hydrogel was significantly greater than it was without surface carboxylation of nanoribbon assemblies or HAp hybridization, suggesting that HAp hybridization to surface-carboxylated nanoribbon assemblies is essential for improving the mechanical properties of cellulose oligomer hydrogels. Our findings open a new avenue for production of synthetic nanocellulose–inorganic hybrid materials with advanced functions