Absolute timing of the photoelectric effect.

Photoemission spectroscopy is central to understanding the inner workings of condensed matter, from simple metals and semiconductors to complex materials such as Mott insulators and superconductors1. Most state-of-the-art knowledge about such solids stems from spectroscopic investigations, and use of subfemtosecond light pulses can provide a time-domain perspective. For example, attosecond (10-18 seconds) metrology allows electron wave packet creation, transport and scattering to be followed on atomic length scales and on attosecond timescales2-7. However, previous studies could not disclose the duration of these processes, because the arrival time of the photons was not known with attosecond precision. Here we show that this main source of ambiguity can be overcome by introducing the atomic chronoscope method, which references all measured timings to the moment of light-pulse arrival and therefore provides absolute timing of the processes under scrutiny. Our proof-of-principle experiment reveals that photoemission from the tungsten conduction band can proceed faster than previously anticipated. By contrast, the duration of electron emanation from core states is correctly described by semiclassical modelling. These findings highlight the necessity of treating the origin, initial excitation and transport of electrons in advanced modelling of the attosecond response of solids, and our absolute data provide a benchmark. Starting from a robustly characterized surface, we then extend attosecond spectroscopy towards isolating the emission properties of atomic adsorbates on surfaces and demonstrate that these act as photoemitters with instantaneous response. We also find that the tungsten core-electron timing remains unchanged by the adsorption of less than one monolayer of dielectric atoms, providing a starting point for the exploration of excitation and charge migration in technologically and biologically relevant adsorbate systems.

Pancreatic pseudocysts complicated by splenic parenchymal involvement: results of operative and percutaneous management.

UNLABELLED: Pancreatic pseudocysts are a common finding in acute and chronic pancreatitis, but most are small and uncomplicated, and do not require treatment. Pseudocysts with splenic parenchymal involvement are uncommon but have the potential for massive hemorrhage. Data on the clinical presentation and optimal treatment of this unusual complication of pseudocysts are lacking. The purpose of this review was to identify the clinical features of pancreatic pseudocysts complicated by splenic parenchymal involvement and to determine the outcome with nonoperative and operative therapy. METHODS: A retrospective review of the medical records of all patients with pancreatic pseudocysts from December 1984 to January 1999 revealed 238 patients, of whom 14 (6%) had splenic parenchymal involvement. These medical records were reviewed in detail and all pertinent radiographs were reviewed by the authors to confirm splenic parenchymal involvement by a pancreatic pseudocyst. RESULTS: Initial treatment included observation (n = 2), percutaneous drainage (n = 8), and surgery (n = 4). Of the eight patients treated by percutaneous drainage, one died, three required repeated percutaneous drainage, and three required surgical intervention. None of the patients treated primarily by surgery required additional therapy for the pseudocyst. Overall, 11 patients had complications of the primary therapy, and 25% of patients treated by surgery had significant hemorrhage. Complications included infection (n = 5), pseudocyst persistence (n = 4), bleeding (n = 2), multisystem organ failure (n = 2), gastric outlet obstruction (n = 1), and splenic rupture (n = 2). CONCLUSIONS: Pancreatic pseudocysts complicated by splenic parenchymal involvement may have life-threatening clinical presentations and respond poorly to percutaneous drainage. Distal pancreatectomy and splenectomy are effective, but the complication rate is high.

Percutaneous drainage of pancreatic pseudocysts is associated with a higher failure rate than surgical treatment in unselected patients.

OBJECTIVE: The primary aim was to compare directly the effectiveness of percutaneous drainage versus surgical treatment of pancreatic pseudocysts in unselected patients. The authors also wished to identify factors that may predict a successful outcome with percutaneous drainage. SUMMARY BACKGROUND DATA: Pancreatic pseudocysts are a common complication of pancreatitis, and recent data suggest that many pseudocysts may be observed or treated successfully by percutaneous drainage. Failures with percutaneous drainage have been recognized increasingly, and a direct comparison of percutaneous and surgical treatment was initiated to identify factors that may affect outcome with these approaches. METHODS: A computerized index search of the medical records of patients with a diagnosis of pancreatic pseudocyst was performed from 1984 to 1995. One hundred seventy-three patients were identified retrospectively and assigned to treatment groups: observation (n = 41), percutaneous drainage (n = 66), or surgical treatment (n = 66). Data on demographics, clinical presentation, pseudocyst etiology and characteristics, diagnostic evaluation, management, and outcome were obtained. Treatment failure was defined as persistence of a symptomatic pseudocyst or the need for additional intervention other than the original treatment. RESULTS: The etiology of pancreatitis, clinical presentation, and diagnostic evaluation did not differ between groups. Twenty-seven percent had documented chronic pancreatitis, and the etiology of pancreatitis was alcohol in 61% of patients. Mean pseudocyst size was 4.2 +/- 1 cm, 8.2 +/- 1.1 cm, and 7.4 +/- 1.3 cm in the observed, percutaneously treated, and surgically treated groups, respectively. Expectant treatment was successful in 93% of patients. Percutaneous drainage was successful in 42% of patients, whereas surgical treatment resulted in a success rate of 88%. Patients treated by percutaneous drainage had a higher mortality rate (16% vs. 0%), a higher incidence of complications (64% vs. 27%), and a longer hospital stay (45 +/- 5 days vs. 18 +/- 2 days) than patients treated by surgery. Eighty-seven percent of patients in whom percutaneous drainage failed required surgical salvage therapy. Multiple logistic regression analysis failed to reveal any factors significantly associated with a successful outcome after percutaneous drainage. CONCLUSIONS: Percutaneous drainage results in higher mortality and morbidity rates and a longer hospital stay than surgical treatment of pancreatic pseudocysts. The clinical benefit of percutaneous drainage of pancreatic pseudocysts in unselected patients has not been realized, and the role of this treatment should be established in a clinical trial.

[Wound closure of the fallopian tube with fibrin glue: endoscopic organ preserving therapy of extrauterine pregnancy]. / Wundverschluss der Tube mittels Fibrinkleber: Endoskopische organerhaltende Therapie der Extrauteringravidität.

OBJECTIVE: In a follow-up study, women with ectopic pregnancies were treated laparoscopically by closing the salpingostomy wound with a fibrin sealant. Their postoperative pregnancy rates and operative results were compared with those of established techniques. METHOD: Ectopic pregnancies were removed by salpingostomy, and the wound was sealed by dripping a fibrin glue onto the (approximated) wound edges. RESULTS: Following salpingostomy and consecutive sealing of the wound, 59 women still wanted to have a baby. Pregnancies occurred in 92%. Intrauterine pregnancies were found in 61%, the relapse rate on the operated side was 15%. After the operation, 5 patients had a second ectopic pregnancy before or after a normal one. In case of the presence of only one or both operated tubes, the intrauterine pregnancy rate was 77% and the relapse rate 11%. All pregnancies were obtained without any medical help, and 41 women (69%) had a healthy baby. CONCLUSION: The simple fibrin sealing technique yielded results comparable to those of the techniques established so far.

Growth and production kinetics of human x mouse and mouse hybridoma cells at reduced temperature and serum content.

The growth and production kinetics of a mouse hybridoma cell line and a human-mouse heterohybridoma were analyzed under conditions of reduced temperature and serum content. The mouse hybridoma P24 had a constant cell specific production rate and RNA content, while the heterohybridoma 3D6-LC4 showed growth associated production kinetics and an increased RNA content at higher growth rates. This behaviour of 3D6-LC4 cells can be explained by the unusual cell cycle kinetics of this line, which can be arrested in any phase under growth limiting conditions, so that a low growth rate does not result in a greater portion of high producing G1-phase cells. Substrate limitation changes the cell cycle distribution of this cell line to a greater extent than low temperature or serum content, which indicates that this stress factor exerts a greater physiological control than assumed.