Spatio-temporal characterization of intense few-cycle 2 µm pulses.

We present a variant of spatially encoded spectral shearing interferometry for measuring two-dimensional spatio-temporal slices of few-cycle pulses centered around 2 µm. We demonstrate experimentally that the device accurately retrieves the pulse-front tilt caused by angular dispersion of two-cycle pulses. We then use the technique to characterize 500-650 µJ pulses from a hollow fiber pulse compressor, with durations as short as 7.1 fs (1.3 optical cycles).

A Case of an Anomalous Tract Involving the Cecum After Open Right Inguinal Hernia Repair.

Inguinal hernia repair is a commonly performed surgical procedure and generally is well tolerated with minimal complications. We present the case of a 70-year-old male with an anomalous tract involving the subcutaneous tissue and cecum after an open right inguinal hernia repair via plug and patch approach. A partial cecectomy with appendectomy with excision of the tract was performed. While most complications are relatively minor and fistulas are quite rare, mesh migration is a possibility that should be considered during preoperative planning for recurrent hernia surgery.

A Concurrent Pseudoaneurysm and an Arteriovenous Fistula Following Percutaneous Radial Artery Access.

The incidence of radial artery cannulation resulting in the concurrent development of a pseudoaneurysm and an arteriovenous fistula is not well defined. Here, we present the case of a 42-year-old man who developed an iatrogenic pseudoaneurysm (PSA) and a concurrent arteriovenous fistula (AVF) following multiple right radial artery cannulations. Access was obtained for a preoperative diagnostic cardiac catheterization and again for hemodynamic monitoring intraoperatively during a surgical aortic valve replacement. A palpable thrill over the right radial artery developed and persisted for nine months, leading to anxiety and mental fixation on the thrill. There were no other symptoms. Given a failed resolution with conservative care for the same duration, the patient elected to proceed with surgical resection. Following resection, the patient reported resolution of his symptoms and decreased anxiety. A follow-up targeted arterial ultrasound demonstrated no residual PSA or AVF.

Trajectory selection in high harmonic generation by controlling the phase between orthogonal two-color fields.

We demonstrate control of short and long quantum trajectories in high harmonic emission through the use of an orthogonally polarized two-color field. By controlling the relative phase ϕ between the two fields we show via classical and quantum calculations that we can steer the two-dimensional trajectories to return, or not, to the core and so control the relative strength of the short or long quantum trajectory contribution. In experiments, we demonstrate that this leads to robust control over the trajectory contributions using a drive field from a femtosecond laser composed of the fundamental ω at 800 nm (intensity ∼1.2×10(14) W cm(-2)) and its weaker orthogonally polarized second harmonic 2ω (intensity ∼0.3×10(14) W cm(-2)) with the relative phase between the ω and 2ω fields varied simply by tilting a fused silica plate. This is the first demonstration of short and long quantum trajectory control at the single-atom level.

Extracting sub-cycle electronic and nuclear dynamics from high harmonic spectra.

We present a new methodology for measuring few-femtosecond electronic and nuclear dynamics in both atoms and polyatomic molecules using multidimensional high harmonic generation (HHG) spectroscopy measurements, in which the spectra are recorded as a function of the laser intensity to form a two-dimensional data set. The method is applied to xenon atoms and to benzene molecules, the latter exhibiting significant fast nuclear dynamics following ionization. We uncover the signature of the sub-cycle evolution of the returning electron flux in strong-field ionized xenon atoms, implicit in the strong field approximation but not previously observed directly. We furthermore extract the nuclear autocorrelation function in strong field ionized benzene cations, which is determined to have a decay of [Formula: see text] fs, in good agreement with the [Formula: see text] fs obtained from direct dynamics variational multi-configuration Gaussian calculations. Our method requires minimal assumptions about the system, and is applicable even to un-aligned polyatomic molecules.

Enhancement of high harmonics generated by field steering of electrons in a two-color orthogonally polarized laser field.

We demonstrate enhancement by 1 order of magnitude of the high-order harmonics generated in argon by combining a fundamental field at 1300 nm (10(14) W cm(-2)) and its orthogonally polarized second harmonic at 650 nm (2 × 10(13) W cm(-2)) and by controlling the relative phase between them. This extends earlier work by ensuring that the main effect is the combined field steering the electron trajectory with negligible contribution from multiphoton effects compared to the previous schemes with 800/400 nm fields. We access a broad energy range of harmonics (from 20 eV to 80 eV) at a low laser intensity (far below the ionization saturation limit) and observe deep modulation of the harmonic yield with a period of π in the relative phase. Strong field theoretical analysis reveals that this is principally due to the steering of the recolliding electron wave packet by the two-color field. Our modeling also shows that the atto chirp can be controlled, leading to production of shorter pulses.

An apparatus for quantitative high-harmonic generation spectroscopy in molecular vapours.

We present an apparatus for performing gas phase high-harmonic generation spectroscopy of molecules primarily found in the liquid phase. Liquid molecular samples are heated in a temperature controlled bath and their vapour is used to back a continuous flow gas jet, with vapour pressures of over 1 bar possible. In order to demonstrate the system, we perform high harmonic spectroscopy experiments in benzene with a 1.8 µm driving field. Using the unique capabilities of the system, we obtain spectra that are nearly free from the effects of longitudinal phase-matching, amenable to comparison with advanced numerical modelling.

Elevated expression of matrix metalloproteinase-13 in abdominal aortic aneurysms.

Destructive remodeling of extracellular matrix has been shown to be present in aneurysmal abdominal aorta. We used real-time quantitative reverse transcriptase polymerase chain reaction to determine the relative expression of matrix metalloproteinase-13 (MMP13) in aortic tissue samples from patients who underwent abdominal aortic aneurysm repair operations (n = 36) and from nonaneurysmal autopsy samples (n = 20). The assays were carried out simultaneously in the same reaction tubes for ribosomal 18S RNA to correct for different amounts of input RNA. MMP13 was expressed in all parts of aorta and its expression was elevated in aneurysmal sac. In further studies using MMP13-specific antibody we demonstrated that MMP13 protein was present in the aneurysmal wall.