Gain dynamics in quickly ionized plasma for seeded operated soft x-ray lasers.

Harmonic seeded operation of a neon-like titanium plasma-based soft x-ray laser is described. The plasma amplifier is pumped with a variation of the grazing incidence technique involving a fast and localized ionization step. We discuss its effect on gain dynamics by measuring the amplifying factor as a function of the delay between pump pulse and harmonic seed. Two different regimes are pointed out, following the pumping scheme used. For one of them, a delay in the gain generation compared with the pumping laser pulse is observed.

Temporal coherence and spectral linewidth of an injection-seeded transient collisional soft x-ray laser.

The temporal coherence of an injection-seeded transient 18.9 nm molybdenum soft x-ray laser was measured using a wavefront division interferometer and compared to model simulations. The seeded laser is found to have a coherence time similar to that of the unseeded amplifier, ~1 ps, but a significantly larger degree of temporal coherence. The measured coherence time for the unseeded amplifier is only a small fraction of the pulsewidth, while in the case of the seeded laser it approaches full temporal coherence. The measurements confirm that the bandwidth of the solid target amplifiers is significantly wider than that of soft x-ray lasers that use gaseous targets, an advantage for the development of sub-picosecond soft x-ray lasers.

Fourier-limited seeded soft x-ray laser pulse.

We present what we believe to be the first measurement of the spectral properties of a soft x-ray laser seeded by a high-order harmonic beam. Using an interferometric method, the spectral profile of a seeded Ni-like krypton soft x-ray laser (32.8 nm) generated by optical field ionization has been experimentally determined, and the shortest possible pulse duration has been deduced. The source exhibits a Voigt spectral profile with an FWHM of 3.1+/-0.3 mA, leading to a Fourier-transform pulse duration of 4.7 ps. This value is comparable with the upper limit of the soft x-ray pulse duration determined by experimentally investigating the gain dynamics, from which we conclude that the source has reached the Fourier limit. The measured bandwidth is in good agreement with the predictions of a radiative transfer code, including gain line narrowing and saturation rebroadening.

Quantitative study of 10 Hz operation of a soft x-ray laser-energy stability and target considerations.

A soft x-ray laser from Ni-like Mo, pumped in grazing incidence (GRIP), is analyzed with regard to high repetition rate operation. Reliable lasing is obtained, but with significant energy fluctuations attributed mainly to beam pointing jitter from the pump laser. Two modes of operation are compared: continuously moving target and stationary target. With a moving target the soft X-ray output is constant on average, whereas the repeated use of the same target position leads to a pulse energy which increases for several tens of shots. This effect might be caused by improved guiding of the pump laser in the formed groove and the removal, through laser ablation, of the oxide layer on the target surface.

Hemoperitoneum in patients receiving hemodialysis.

Acute abdominal pain in chronic hemodialysis patients has well-known causes, including acute pancreatitis, mesenteric arterial insufficiency, or complicated duodenal ulcer. Others, such as hemoperitoneum, are far less common. Although hemoperitoneum occurs in patients receiving peritoneal dialysis, dialysis is seldom if ever the direct cause of the bleeding. Hemoperitoneum is often related to menses or ovulation, particularly to ovarian cyst rupture; therefore, it is more common in young women. In most cases, no specific treatment is required. Hemoperitoneum is rarely considered as the cause of acute abdominal pain in chronic hemodialysis patients. In this report of hemoperitoneum confirmed by emergency laparotomy in 3 women, bleeding was not related to gynecologic origin. All of the women were younger than age 50 and undergoing long-term hemodialysis. All patients had a history of acute abdominal pain associated with shock. The cause of bleeding was always an organ lesion: hepatic amyloidosis with suspected portal hypertension or sclerosing peritonitis and acute hemorrhagic pancreatitis. Coagulation abnormalities and the use of anticoagulants during hemodialysis sessions may have been aggravating factors in all three patients. Hemoperitoneum is difficult to diagnose, particularly in the minor forms, and consequently its incidence may be underestimated. Therefore, it should be considered whenever a chronic hemodialysis patient presents with persistent acute abdominal pain.

Combined idiopathic retroperitoneal and mediastinal fibrosis with pericardial involvement.

We report the case of a 54-year-old woman with renal failure related to bilateral hydronephrosis. Clinical and radiologic findings were consistent with retroperitoneal fibrosis associated with pleuro-pericardial involvement. These features matched criteria for combined idiopathic retroperitoneal fibrosis and idiopathic mediastinal fibrosis. There are few reported cases of pericardial involvement in this combined disorder. In our observation, nuclear-magnetic resonance was the radiologic procedure of choice for aortic exploration. The responsibility of therapeutic agents (beta-adrenoreceptor-blocking drugs and ergotamine) and therapeutic options for the sclerosing disease are also discussed. Bilateral ureteral stents and corticosteroids produced favorable outcome without recurrence one year after treatment was stopped.

[Thyroid disease and multiple autoimmune syndromes. Clinical and immunogenetic aspects apropos of 11 cases]. / Pathologie thyroïdienne et syndromes auto-immuns multiples. Aspects clinique et immunogénétique à propos de 11 observations.

The authors report eleven cases of multiple auto-immune syndrome, concerning a total of 15 different auto-immune diseases. This study suggests that auto-immune thyroid disorders (Graves' disease or hypothyroidism resulting from Hashimoto's thyroiditis) are a common feature of multiple auto-immune syndromes, while antithyroid antibodies are constant among our patients. Sjögren's syndrome is also very prevalent, and seems to be non-randomly associated with auto-immune thyroid disorders, a fact which suggests common aetiological factors. Among other auto-immune disorders, the antiphospholipid syndrome has been diagnosed twice. A genetic predisposition to multiple auto-immune syndrome is obvious, as shown by a familial history of auto-immune disorders (found in more than half of the cases), and a predominant HLA phenotype, B8 and/or DR3. The authors plead for a systematic enquiry for multiple auto-immune syndrome in patients with auto-immune thyroid disorders and a family history of auto-immune disorders.

[Vitiligo in multiple autoimmune syndrome: a retrospective study of 11 cases and a review of the literature]. / Le vitiligo au cours des syndromes auto-immuns multiples: étude rétrospective de 11 observations et revue de la littérature.

PURPOSE: The occurrence in the same patient of three or more autoimmune diseases defines multiple autoimmune disease. Multiple autoimmune disease is an unusual condition in which dermatological autoimmune diseases and especially vitiligo have an important place. METHODS: We examined retrospectively 11 cases of multiple autoimmune diseases associating vitiligo. We studied the clinical characteristics of vitiligo and those of the associated autoimmune disorders. RESULTS: Type III multiple autoimmune disease was diagnosed in all the 11 cases observed. Autoimmune vitiligo was the first autoimmune disorder observed in seven cases and was bilateral, symmetrical and acrofacial in eight cases. Autoimmune thyroid disorder was associated in ten cases. Our data confirms the important association between vitiligo and thyroid autoimmune disorders. CONCLUSION: The predominant female ratio and the acrofacial topography of skin lesions could predict association with others autoimmune disorders in patients with vitiligo.

[Rotavirus infection associated with adult thrombotic microangiopathy]. / Infection à Rotavirus associée à la survenue d'une microangiopathie thrombotique de l'adulte.

BACKGROUND: A preceding viral syndrome is classically cited as a triggering factor for thrombotic microangiopathy although only anecdotal reports of the causal agent have been documented. CASE REPORT: An 84-year-old woman developed thrombotic microangiopathy secondary to diarrhea. An exhaustive etiological work-up documented the presence of Rotavirus alone in the fecal matter. The clinical course was favorable after 9 plasma exchanges using frozen fresh plasma and was associated with disappearance of the Rotavirus. DISCUSSION: Enterohemorrhagic Escherichia coli is the most commonly identified infectious agent causing thrombotic microangiopathy. A small number of cases caused by viral agents (particularly retroviruses) have also been documented. To our knowledge, this is the first case attributable to a Rotavirus. In our case, the presence of the Rotavirus in the fecal matter and the favorable clinical course when the virus disappeared would be in favor of its causal role in the pathogenesis of thrombotic micorangiopathy.

[Association of acute pericarditis and acute renal insufficiency: causes and prognosis]. / Association d'une péricardite aiguë à une insuffisance rénale aiguë: causes et pronostic. 11 observations.

OBJECTIVE: To assess the etiologic diagnoses and outcome of acute pericardial effusion associated to acute renal renal failure. PATIENTS AND METHODS: A retrospective study from 1978 to 1996 in a 10 bed medical/surgical intensive care unit included 11 patients who have an acute pericardial effusion associated with an acute renal failure. RESULTS: Etiological diagnoses were systemic lupus with extracapillary glomerulonephritis (n = 2), systemic fibrosis with obstructive renal failure (n = 2), anticoagulation accident with hemodynamic renal failure (n = 2), lung adenocarcinoma (n = 2), adenocarcinoma of undetermined origin (n = 1), systemic polyarteritis nodosa (n = 1), and Wegener granulomatosis (n = 1). Intensive care unit deaths was 4, including 2 cases of neoplasic origin. DISCUSSION: Despite infection or malignancy being claimed as the leading causes of acute pericardial effusion, when associated to acute renal failure other etiologic diagnoses, such connectivite tissue disease or vasculitis, must be evoked that prompt specific treatment and could prevent unfavorable evolution. Neoplasic causes were characterised by receiving pericardial effusion and a high mortality rate.

[Cervical spinal cord compression caused by ossification of the posterior vertebral ligament. Apropos of a case]. / Compression médullaire cervicale par ossification du ligament vertébral commun postérieur. A propos d'un cas.

Progressive cervical myelopathy due to an ossification of the posterior longitudinal ligament (OPLL) appeared in a sicilian women. Diagnosis was made by lateral conventional tomograms and CT Scan with mielography. Corporectomy of the 5th vertebra and ablation of the ligament dramatically improved the clinical symptoms. If OPLL seems a common cause of cervical myelopathy in Japan, it is very rate in Caucasian people. Instead of the origin of the patients, progressive tetraparesis of the 60 years old people is the usual presentation of this affection. The cause of OPLL remains unknown: genetic factors, vitamin A, association with diffuse idiopathic skeletal hyperostosis, calcium metabolism abnormalities are discussed. As far as surgical treatment is concerned, choice between anterior and posterior decompression is clarified on the basis of the type and the extension of OPLL.

Dynamical description of transient x-ray lasers seeded with high-order harmonic radiation through Maxwell-Bloch numerical simulations.

The Maxwell-Bloch code COLAX has been upgraded to use detailed hydrodynamical and collisional-radiative simulations of a soft x-ray laser plasma with traveling-wave pumping. The seeding of short pulses of high-order harmonics of the pump laser into the x-ray laser medium has been simulated. The amplification is shown to be a dynamic, two-stage process: the atomic dipoles of the lasing ions are first coherently excited by the short pulse, and subsequently generate a radiation wake which is amplified along its path through the plasma, with consequences on the experimentally recorded spectra.