Intensity of the Second Heart Sound: Relation of physical, physiological and anatomic factors to auscultatory evaluation

The intensity of the heart sound depends upon: 1) the distensibility of the aortic and pulmonary valves; 2) hemodynamic factors that cause the valves to distend and vibrate; 3) viscosity of the blood and its ability to inhibit diastolic valve motion; 4) the configuration of the aorta, pulmonary artery, and ventricle and the ability of the walls of the great vessels and ventricles to absorb or reflect sound energy; and 5) the capability of sound to be transmitted to the chest wall. Recognizing how these physical, physiological, and anatomic factors interact can help us to interpret auscultation of the intensity of the second heart sound

Femtosecond Pump-Probe Reflectivity Study of Silicon Carrier Dynamics

We have studied the ultrafast optical response of native-oxide terminated Si(001) with pump-probe reflectivity using 800 nm, 28 fs pulses at an excitation density of (5.5±0.3)×1018cm-3. Time-dependent reflectivity changes comprise third-order-response coherent-transient variations arising from anisotropic state filling and linear-response variations arising from excited free carriers, state filling, and lattice heating. A time constant of 32±5fs associated with momentum relaxation is extracted from the coherent-transient variations. The state-filling and free-carrier responses are sensitive to carrier temperature, allowing an electron-phonon energy relaxation time of 260±30fs to be measured. The recovery of the reflectivity signal back towards its initial value is largely governed surface recombination: a surface recombination velocity of (3±1)×104cm s-1 is deduced for native-oxide terminated Si(001)

Percutaneously Inserted AngioVac Suction Thrombectomy for the Treatment of Filter-Related Iliocaval Thrombosis

In the setting of acute iliocaval thrombosis due to reversible causes, thrombus removal is preferred by many in the management of inferior vena cava (IVC) thrombosis as it is thought likely to minimize the long-term complications of chronic venous insufficiency and post-thrombotic syndrome. When catheter-directed thrombolysis is not a viable or effective option, the treatment options are limited. We present the case of a 56-year-old hospitalized patient with a permanent IVC filter that had been inserted 10 years prior at an outside hospital with severe, incapacitating right leg swelling for which amputation was considered. The patient underwent suction thrombectomy after failure of thrombolysis. The patient’s presenting symptoms of right lower extremity swelling and pain improved upon discharge. In our single case, unassisted suction thrombectomy with percutaneously placed cannulae is an effective and safe method for the treatment of permanent IVC filter-related iliocaval thrombosis in cases refractory to catheter-directed thrombolysis

A Compact Rotating-Mirror Autocorrelator Design for Femtosecond and Picosecond LaserPulses

An interferometric rapid-scanning autocorrelator employing two antiparallel rotating mirrors in a variable arm is optimized for maximum optical path difference as a function of the separation of the two rotating mirrors. A very compact design (mirror separation≈mirror diameter) is possible without a reduction in the maximum pulse width that can be measured

Measurement of Silicon Surface Recombination Velocity Using Ultrafast Pump-Probe Reflectivityin the Near Infrared

We demonstrate that ultrafast pump–probe reflectivity measurements from bulk Si samples using a Ti:sapphire femtosecond oscillator (λ=800 nm) can be used to measure the Si surface recombination velocity. The technique is sensitive to recombination velocities greater than ∼104 cm s−

Coherent Excitation of the Optic Phonon in Si: Transiently Stimulated Raman Scattering with aFinite-Lifetime Electronic Excitation

Using 28-fs, 800-nm laser pulses we have coherently excited and subsequently probed, with time-dependent reflectivity, the Si zone-center optic phonon. The phonon-induced reflectivity change ΔR∕R is well described by the response of an underdamped oscillator: ΔR∕R∝ exp(−t∕τph) cos(2πt∕Tph+ϕ). The measured phase ϕ indicates that transiently stimulated Raman scattering (TSRS) is responsible for the coherent-phonon generation: our results are in good agreement with a recent theory of TSRS for opaque materials [ T. E. Stevens et al. Phys. Rev. B 65 144304 (2002)] when we extend the theory to include the finite lifetime of the excited charge density that couples to the oscillation. We also discuss previous experimental results on Te, Bi, Sb, Si, and Ge in light of this extended theory. Additionally, our measured period Tph and decay time τph of the Si coherent oscillation are consistent with carrier-density-dependent Raman-scattering measurements

Evaluation of the influence of leaflet stiffening on leaflet stresses of porcine bioprosthetic valves using a finite element model

AbstractThe magnitude and distribution of mechanical stresses acting on the closed cusps of porcine bioprosthetic valves were estimated using a finite element model. Leaflet stresses were calculated using reported stress-strain properties of glutaraldehyde processed normal porcine valves and stress-strain properties of porcine valve leaflets stiffened by fatigue cycling (658 x 10 cycles). In the normal leaflet, at a pressure of 80 mm Hg, stresses were highest near the commissures (140 kPa), decreased near the center of the leaflet (110 kPa) and were lowest near the base of the leaflet (30 kPa). With increased leaflet stiffening, stresses near the commissures remained relatively unchanged (140 kPa). Stresses near the center of the leaflet, however, increased markedly (170 kPa). With increased leaflet stiffening, stresses near the base of the leaflet remained the lowest (60 kPa). The development of a site of stress concentration near the center of the leaflet following leaflet stiffening, may offer a clue to the etiology of leaflet perforations reported to occur in the central region of leaflets of degenerated porcine bioprosthetic valves

The Pulmonary Component of the Second Sound in Right Ventricular Failure

Sound within the pulmonary artery was measured in 24 patients to determine if right ventricular failure modifies the amplitude of the pulmonary component of the second sound (P2). The amplitude of P2 in eight patients with right ventricular failure secondary to pulmonary hypertension (2610 ± 370 dynes/cm2) did not differ from P2 in eight patients with pulmonary hypertension not accompanied by right ventricular failure (3120 ± 710 dynes/cm2). In both groups, the amplitude of P2 exceeded control subjects (520 ± 70 dynes/cm2) (P \u3c .001 and P \u3c .01, respectively). The maximal rate of development of the pressure gradient across the closed pulmonary valve was higher in patients with right ventricular failure (580 ± 100 mm Hg/sec) than in control subjects (150 ± 30 mm Hg/sec) (P \u3c .001) and maximal negative dp/dt was also higher in patients with failure (750 ± 70 mm Hg/sec vs 190 ± 20 mm Hg/sec) (P \u3c .001). The maximal rate of change of the diastolic pressure gradient correlated linearly with maximal negative dp/dt (r=.89). These observations indicate that P2 is accentuated in patients with right ventricular failure secondary to pulmonary hypertension. The accentuation results from the augmented rate of development of the diastolic pressure gradient, which reflects an augmented right ventricular negative dp/dt. Therefore, an accentuated P2 remains valid as a clinical sign of pulmonary hypertension whether or not right ventricular failure occurs

Analytic continuation of residue currents

Let $X$ be a complex manifold and f\colon X\to \C^p a holomorphic mapping defining a complete intersection. We prove that the iterated Mellin transform of the residue integral associated to $f$ has an analytic continuation to a neighborhood of the origin in \C^p