Enhanced Molecular Spin-Photon Coupling at Superconducting Nanoconstrictions.

We combine top-down and bottom-up nanolithography to optimize the coupling of small molecular spin ensembles to 1.4 GHz on-chip superconducting resonators. Nanoscopic constrictions, fabricated with a focused ion beam at the central transmission line, locally concentrate the microwave magnetic field. Drops of free-radical molecules have been deposited from solution onto the circuits. For the smallest ones, the molecules were delivered at the relevant circuit areas by means of an atomic force microscope. The number of spins Neff effectively coupled to each device was accurately determined combining Scanning Electron and Atomic Force Microscopies. The collective spin-photon coupling constant has been determined for samples with Neff ranging between 2 × 106 and 1012 spins, and for temperatures down to 44 mK. The results show the well-known collective enhancement of the coupling proportional to the square root of Neff. The average coupling of individual spins is enhanced by more than 4 orders of magnitude (from 4 mHz up to above 180 Hz), when the transmission line width is reduced from 400 µm down to 42 nm, and reaches maximum values near 1 kHz for molecules located on the smallest nanoconstrictions.

A retrospective analysis of the aspiration of fracture blisters.

INTRODUCTION: Fracture blisters are frequently encountered in orthopaedic trauma. Fracture blisters are associated with increased infection rates and wound breakdown. This study was performed to determine whether fluid aspirate from blisters is sterile or colonized. MATERIALS AND METHODS: This is a retrospective review of a prospectively gathered cohort of patients. Patients with fracture blisters were recruited from a U.S. level I trauma center between 2011 and 2017. The blisters were aspirated under sterile conditions. Fluid was analyzed for gram stain and quantitative culture. Medical history obtained included blister location, presence of blood in blister, injury mechanism, gender, diabetes status and tobacco use. The demographic and behavioral descriptors were compared across positive aspirate or infection status using chi-square and Fisher's exact tests. RESULTS: We enrolled 64 patients in the study, seven of which had colonized aspirates (10.9%). None of the potential risk factors were significantly associated. Tobacco use trended towards significance for a positive aspirate (p = 0.09), but not for infection (p = 0.61). We followed patients for an average of 4.6 months. Four patients went on to have surgical site infections and none of them had positive aspirates. CONCLUSION: Fracture blisters cannot be assumed to be sterile with more than 10% of our sample being colonized. Blister rupture during surgery or prepping for surgery could represent a contamination of the sterile field. No risk factors were significantly associated with colonization in our sample. However, colonized aspirates may not predispose patients to increased infection rates.

Sciatic Nerve Palsy After Distal Femoral Traction for Vertically Unstable Pelvic Fracture in a Neurologically Intact Patient.

Vertically unstable fractures of the pelvis require a notable amount of energy to cause disruption of the posterior elements of the pelvic ring. Superior migration of the hemipelvis demonstrates the inherent instability of this fracture pattern. Surgical fixation is required in most cases, but while resuscitation efforts are underway, placing the patient in skeletal traction to reduce the hemipelvis is often recommended. Although skeletal traction has been described in many sources, no consensus exists on the amount of weight that should be used. This has led to anecdotal recommendations that vary between institutions. Without clear guidelines for treatment, a vertically translated hemipelvis was overreduced and subsequently sustained a sciatic nerve palsy in a patient who was neurologically intact on presentation. We aim to describe a rare complication of skeletal traction and propose a treatment algorithm to reduce the incidence of future complications.

Observation and stabilization of photonic Fock states in a hot radio-frequency resonator.

Detecting weak radio-frequency electromagnetic fields plays a crucial role in a wide range of fields, from radio astronomy to nuclear magnetic resonance imaging. In quantum optics, the ultimate limit of a weak field is a single photon. Detecting and manipulating single photons at megahertz frequencies presents a challenge because, even at cryogenic temperatures, thermal fluctuations are appreciable. Using a gigahertz superconducting qubit, we observed the quantization of a megahertz radio-frequency resonator, cooled it to the ground state, and stabilized Fock states. Releasing the resonator from our control, we observed its rethermalization with nanosecond resolution. Extending circuit quantum electrodynamics to the megahertz regime, we have enabled the exploration of thermodynamics at the quantum scale and allowed interfacing quantum circuits with megahertz systems such as spin systems or macroscopic mechanical oscillators.

A ballistic graphene superconducting microwave circuit.

Josephson junctions (JJ) are a fundamental component of microwave quantum circuits, such as tunable cavities, qubits, and parametric amplifiers. Recently developed encapsulated graphene JJs, with supercurrents extending over micron distance scales, have exciting potential applications as a new building block for quantum circuits. Despite this, the microwave performance of this technology has not been explored. Here, we demonstrate a microwave circuit based on a ballistic graphene JJ embedded in a superconducting cavity. We directly observe a gate-tunable Josephson inductance through the resonance frequency of the device and, using a detailed RF model, we extract this inductance quantitatively. We also observe the microwave losses of the device, and translate this into sub-gap resistances of the junction at µeV energy scales, not accessible in DC measurements. The microwave performance we observe here suggests that graphene Josephson junctions are a feasible platform for implementing coherent quantum circuits.

Early weight bearing after complete tibial shaft fractures in children.

This study determined the prevalence of complications related to early weight bearing and the factors associated with time to healing in children after a complete tibial shaft fracture. Radiographs and medical records were reviewed from patients with unilateral, closed, complete tibial shaft fractures who were treated nonoperatively with a long leg cast. There were 55 males (68.8%) and 25 females (31.2%) with a mean ± SD age of 6.0 ± 4.0 years (range 1-16). There were few complications (2.5%) and patients healed faster if they bore weight earlier (0.3 days faster for each day earlier to weight bearing, P = 0.02), were younger (2.3 days faster per year younger, P < 0.001), were female (2.7 days faster than males, P = 0.02), or did not have a closed reduction (3.8 days faster, P = 0.002) (R = 0.63). Time to weight bearing after complete tibial shaft fracture was not associated with an increased risk of complications. Earlier weight bearing was associated with a shorter time to healing. This study provides support for treatment with early weight bearing in children with closed, complete tibial shaft fractures.

Structural refinement of the 8,9-dihydro-8-(N7-guanyl)-9-hydroxy-aflatoxin B(1) adduct in a 5'-Cp(AFB)G-3' sequence.

The structure of the cationic 8,9-dihydro-8-(N7-guanyl)-9-hydroxy-aflatoxin B(1) adduct embedded in a 5'-CpG-3' sequence context and paired with deoxycytosine in the oligodeoxynucleotide d(ACATC(AFB)GATCT) x d(AGATCGATGT) was refined using molecular dynamics calculations restrained by NOE data and dihedral angle restraints obtained from NMR data. The aflatoxin moiety intercalated above the 5' face of the modified guanine. It stacked between C(5) x G(16) and (AFB)G(6) x C(15). The AFB(1) H5, OCH(3), and methylene protons faced into the minor groove, with the methylene protons oriented between the C(15) and G(16) nucleobases. The aflatoxin B(1) H6a, H8, H9, and H9a protons faced the major groove, with H6a and H9a pointing toward the 5' direction from the lesion site. The refined structure was compared to the structure of the aflatoxin B(1) adduct embedded in a 5'-ATGCAT-3' sequence in the oligodeoxynucleotide d(TAT(AFB)GCATA)(2) [Jones, W. R., Johnston, D. S., and Stone, M. P. (1998) Chem. Res. Toxicol.11, 873-881]. The structure of the intercalated aflatoxin B(1) lesion in the ATC(AFB)GAT sequence is similar to its structure in the d(AT(AFB)GCAT) sequence. This is consistent with a mechanism in which the precovalent intercalation of aflatoxin-8,9-exo-epoxide on the 5' face of guanine places the epoxide in close proximity and in the proper orientation to the N7 position of guanine, thus facilitating an S(N)2 reaction. The data provides additional insight into the nature of the disruption of the B-DNA duplex induced by aflatoxin B(1) intercalation. Overall, the results suggest that sequence contributes a minor role in modulating the structure of the cationic guanine N7 AFB(1) lesion in duplex DNA. On the other hand, structural differences are observed when the correctly paired structure is compared to the structure of the cationic AFB(1) adduct mispaired with dA [Giri, I., Johnston, D. S., and Stone, M. P. (2002) Biochemistry 41, 5462-5472].