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

Efficient Solid-Phase Synthesis of Symmetric Norbinaltorphimine Derivatives

We describe an efficient solid-phase synthesis of symmetric norbinaltorphimine (norBNI) derivatives 2. Pyrrole formation involving the homocoupling of two solid-supported ketones 6, followed by chemoselective and sequential N-alkylation, provided N-substituted norBNI derivatives 2. Use of this methodology led to the combinatorial synthesis of 120 norBNI derivatives

An Efficient Convergent Synthesis of GP1c Ganglioside Epitope

An Efficient Convergent Synthesis of GP1c Ganglioside Epitop

Efficient Solid-Phase Synthesis of Symmetric Norbinaltorphimine Derivatives

We describe an efficient solid-phase synthesis of symmetric norbinaltorphimine (norBNI) derivatives 2. Pyrrole formation involving the homocoupling of two solid-supported ketones 6, followed by chemoselective and sequential N-alkylation, provided N-substituted norBNI derivatives 2. Use of this methodology led to the combinatorial synthesis of 120 norBNI derivatives

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

Stereoselective Synthesis of α(2,9) Di- to Tetrasialic Acids, Using a 5,4-<i>N</i>,<i>O</i>-Carbonyl Protected Thiosialoside

An efficient stereoselective synthesis of α(2,9) tetra- to disialic acids 1−3, using the 5,4-N,O-carbonyl protected thiosialoside 4, is described. The cyclic protecting group was effective for α-sialylation without the need for acetonitrile as the solvent. The donor 4 enabled the formation of a tetramer in excellent yield and selectivity. Deprotection of the cyclic protecting groups of the protected di- to tetrasialica acids proceeded smoothly to give the fully deprotected α(2,9) tetra- to disialic acids 1−3

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

An Efficient Convergent Synthesis of GP1c Ganglioside Epitope

An Efficient Convergent Synthesis of GP1c Ganglioside Epitop

Stereoselective Synthesis of Oligo-α-(2,8)-Sialic Acids

An efficient and elegant synthesis of α(2,8)-oligosialosides is described. The 5-N,4-O-carbonyl-protected sialyl donor undergoes α-sialylation in CH2Cl2 to give α(2,8)- and α(2,9)-disialosides in excellent yields. The 5-N,4-O-carbonyl protecting group was effective in improving the reactivity of the C8 hydroxyl groups toward glycosylation. Using the sialyl building block, the synthesis of tetra-α(2,8)-sialic acid was accomplished by using a simple glycosidation and deprotection protocol