Validity of dynamical analysis to characterize heart rate and oxygen consumption during effort tests.

Performance is usually assessed by simple indices stemming from cardiac and respiratory data measured during graded exercise test. The goal of this study is to characterize the indices produced by a dynamical analysis of HR and VO2 for different effort test protocols, and to estimate the construct validity of these new dynamical indices by testing their links with their standard counterparts. Therefore, two groups of 32 and 14 athletes from two different cohorts performed two different graded exercise testing before and after a period of training or deconditioning. Heart rate (HR) and oxygen consumption (VO2) were measured. The new dynamical indices were the value without effort, the characteristic time and the amplitude (gain) of the HR and VO2 response to the effort. The gain of HR was moderately to strongly associated with other performance indices, while the gain for VO2 increased with training and decreased with deconditioning with an effect size slightly higher than VO2 max. Dynamical analysis performed on the first 2/3 of the effort tests showed similar patterns than the analysis of the entire effort tests, which could be useful to assess individuals who cannot perform full effort tests. In conclusion, the dynamical analysis of HR and VO2 obtained during effort test, especially through the estimation of the gain, provides a good characterization of physical performance, robust to less stringent effort test conditions.

Gas-Solid Phase Transition in Laser Multiple Filamentation.

While propagating in transparent media, near-infrared multiterawatt (TW) laser beams break up in a multitude of filaments of typically 100-200 um diameter with peak intensities as high as 10 to 100 TW/cm^{2}. We observe a phase transition at incident beam intensities of 0.4 TW/cm^{2}, where the interaction between filaments induce solidlike two-dimensional crystals with a 2.7 mm lattice constant, independent of the initial beam diameter. Below 0.4 TW/cm^{2}, we evidence a mixed phase state in which some filaments are closely packed in localized clusters, nucleated on inhomogeneities (seeds) in the transverse intensity profile of the beam, and other are sparse with almost no interaction with their neighbors, similar to a gas. This analogy with a thermodynamic gas-solid phase transition is confirmed by calculating the interaction Hamiltonian between neighboring filaments, which takes into account the effect of diffraction, Kerr self-focusing, and plasma generation. The shape of the effective potential is close to a Morse potential with an equilibrium bond length close to the observed value.

Ultrafast nonlinear optical response of a single gold nanorod near its surface plasmon resonance.

The ultrafast optical nonlinearity of an optically characterized single gold nanorod is investigated around its surface plasmon resonance, by combining a far-field spatial modulation technique with a high sensitivity pump-probe setup. The spectrally and temporally dependent response is quantitatively interpreted in terms of the bulklike optical nonlinearity enhanced by the plasmonic effect. The plasmon resonance dynamics is shown to be mostly governed by nonequilibrium electron and phonon processes. Their contributions to the nonlinear optical response of a single metal nano-object are elucidated, and the latter is connected to the nonlinearities of ensembles.

Renal autotransplantation versus bypass techniques for renovascular hypertension.

From 1972 to 1983, 78 patients underwent surgical treatment for renovascular hypertension caused by a lesion limited to the trunk of the renal artery. Forty-five of these patients underwent aortorenal bypass (24 saphenous grafts and 21 arterial hypogastric grafts); 36 patients (80%) had either a relief of the hypertension or were improved. Graft closure occurred in five cases. Thirty-three patients were treated by autotransplantation of the kidney. After resection of the lesion, the renal artery was anastomosed end-to-end to the hypogastric artery or end-to-side to the common iliac artery and the renal vein and side-to-side to the iliac vein or the origin of the vena cava. In this group all patients but one (97%) had relief of the hypertension or were improved. No thrombosis was observed. Late angiography was performed 5 years after surgery in 19 patients (nine autotransplantations and 10 bypass operations): patients who underwent autotransplantation had no alteration of the renal vessels whereas four patients who underwent bypass operations had dilatation of the saphenous vein bypass. Renal autotransplantation was superior to the bypass technique in the surgical treatment of renovascular hypertension caused by lesions of the trunk of the renal artery and may represent a better alternative in the surgical treatment of this condition.

Extracorporeal replacement of the renal artery: techniques, indications and long-term results.

Extracorporeal repair of the renal artery was done in 24 patients for complex lesions extending to branches of the renal artery (9 dysplasias, 5 atheromas and 10 aneurysms). The renal artery and its branches were replaced by a hypogastric branched autograft in 20 patients and a saphenous vein graft in 4. Indications for an extracorporeal operation were hypertension, preservation of renal function against progressive deterioration and extension of the lesion to more than 2 branches of the renal artery. Of 76 peripheral anastomoses 68 were patent postoperatively. Two secondary nephrectomies were performed. Mean followup was 54 months. Hypertension was cured in 19 patients and improved in 2, while 2 failed treatment and 1 died. An extracorporeal operation may represent the best alternative for treatment of renal arterial lesions involving more than 2 branches.

Aneurysms of the renal artery: surgical management with special reference to extracorporeal surgery and autotransplantation.

27 patients underwent surgical arterial reconstruction for renal artery aneurysms. Hypertension was present in 21 cases. The indication for surgery was the prevention of hemorrhagic rupture in association with hypertension. Extracorporeal surgery was performed 13 times for complex aneurysms involving several branches of the renal artery. Simple autotransplantation was performed 3 times for aneurysms located on the main renal artery. In situ surgery was performed on 11 patients (5 aneurysmectomy-arteriorrhaphies and 7 bypass operations). Results on high blood pressure showed that 10 of the 14 hypertensive patients operated by extracorporeal surgery and/or autotransplantation were cured. 1 delayed nephrectomy was performed in this group and 1 death was observed. 39 of the 46 peripheral anastomoses were patent postoperatively. All patients treated with aneurysmectomy-arteriorrhaphy were cured. In patients treated with bypass operations, 3 thromboses of the bypass and 2 failures on hypertension were observed. Aneurysmectomy and simple arterioplasty are preferred for simple renal artery aneurysms. For complex lesions involving several branches and of an intrarenal location, extracorporeal surgery and autotransplantation represent an effective treatment on hypertension and preservation of kidney function.