Novel collective autoionization process observed in electron spectra of He clusters.

The ionization dynamics of He nanodroplets irradiated with intense femtosecond extreme ultraviolet pulses of up to 1013 W/cm2 power density have been investigated by photoelectron spectroscopy. Helium droplets were resonantly excited to atomiclike 2p states with a photon energy of 21.4 eV, below the ionization potential (Ip), and directly into the ionization continuum with 42.8 eV photons. While electron emission following direct ionization above Ip is well explained within a model based on a sequence of direct electron emission events, the resonant excitation provides evidence of a new, collective ionization mechanism involving many excited atomiclike 2p states. With increasing power density the direct photoline due to an interatomic Coulombic decay disappears. It indicates that ionization occurs due to energy exchange between at least three excited atoms proceeding on a femtosecond time scale. In agreement with recent theoretical work the novel ionization process is very efficient and it is expected to be important for many other systems.

[Quality of the diet and lifestyles in health sciences students]. / Calidad de la dieta y estilos de vida en estudiantes de ciencias de la salud.

OBJECTIVE: To evaluate the eating habits of the students of the University of Alicante of the degrees of Human Nutrition and Dietetics and Nursing. MATERIAL AND METHODS: The study was carried out to 184 students of both sexes (96 of Human Nutrition and Dietetics and Nursing 88) of the University of Alicante. Were weighed and carved to calculate BMI; food consumption was estimated by the reminder of 24 hours; intake of macro and micronutrients were calculated using the program Easydiet. Comparing the results obtained in both qualifications and according to nutritional status by performing the corresponding statistical analysis. RESULTS: The majority of the students analyzed are normal weight (80%). There were significant differences in the quality of the diet both degrees, being the same characteristics: low in carbohydrates and high in protein. It also shows an imbalance in the type of fat consumed, with a higher consumption of saturated and less from polyunsaturated than recommended. Likewise, analyzed that nutrition students do more exercise than the nurses, although they sleep fewer hours and spend more time in front of the computer and TV. CONCLUSION: While the levels of overweight and obesity among students is less than that of the general population, there are imbalances in your diet, noting that consumption of macronutrients is located away from the recommendations, and that there are deficiencies in the intake of micronutrients. Showing that have knowledge of nutrition, does not affect healthy decision-making to a diet and lifestyle.

Collective autoionization in multiply-excited systems: a novel ionization process observed in helium nanodroplets.

Free electron lasers (FELs) offer the unprecedented capability to study reaction dynamics and image the structure of complex systems. When multiple photons are absorbed in complex systems, a plasma-like state is formed where many atoms are ionized on a femtosecond timescale. If multiphoton absorption is resonantly-enhanced, the system becomes electronically-excited prior to plasma formation, with subsequent decay paths which have been scarcely investigated to date. Here, we show using helium nanodroplets as an example that these systems can decay by a new type of process, named collective autoionization. In addition, we show that this process is surprisingly efficient, leading to ion abundances much greater than that of direct single-photon ionization. This novel collective ionization process is expected to be important in many other complex systems, e.g. macromolecules and nanoparticles, exposed to high intensity radiation fields.

Extreme ultraviolet ionization of pure He nanodroplets: mass-correlated photoelectron imaging, Penning ionization, and electron energy-loss spectra.

The ionization dynamics of pure He nanodroplets irradiated by Extreme ultraviolet radiation is studied using Velocity-Map Imaging PhotoElectron-PhotoIon COincidence spectroscopy. We present photoelectron energy spectra and angular distributions measured in coincidence with the most abundant ions He(+), He2(+), and He3(+). Surprisingly, below the autoionization threshold of He droplets, we find indications for multiple excitation and subsequent ionization of the droplets by a Penning-like process. At high photon energies we observe inelastic collisions of photoelectrons with the surrounding He atoms in the droplets.

On the application of a monolithic array for detecting intensity-correlated photons emitted by different source types.

It is not widely appreciated that many subtleties are involved in the accurate measurement of intensity-correlated photons; even for the original experiments of Hanbury Brown and Twiss (HBT). Using a monolithic 4 x 4 array of single-photon avalanche diodes (SPADs), together with an off-chip algorithm for processing streaming data, we investigate the difficulties of measuring second-order photon correlations g((2))(x(iota), t(iota),x, t) in a wide variety of light fields that exhibit dramatically different correlation statistics: a multimode He-Ne laser, an incoherent intensity-modulated lamp-light source and a thermal light source. Our off-chip algorithm treats multiple photon-arrivals at pixel-array pairs, in any observation interval, with photon fluxes limited by detector saturation, in such a way that a correctly normalized g((2)) function is guaranteed. The impact of detector background correlations between SPAD pixels and afterpulsing effects on second-order coherence measurements is discussed. These results demonstrate that our monolithic SPAD array enables access to effects that are otherwise impossible to measure with stand-alone detectors.

[Influence of postoperative radiation therapy of cerebral metastases on survival time and disease related to living condition]. / Einfluss der postoperativen Nachbestrahlung zerebraler Metastasen auf Uberlebenszeit und krankheitsbedingte Lebensbedingungen der Patienten.

Cerebral metastases are frequently observed in patients with systemic carcinoma as indication for new progress of the disease. Neurological deficits or seizures indicating cerebral metastases reduce the disease-related living conditions of the patients. Improving quality of life and survival time is the overriding goal of an early treatment after the diagnosis of cerebral metastases. Contemporary treatment include surgical removal of the cerebral metastases followed by whole brain irradiation and in some cases additional systemic chemotherapy for the primary tumor. This study was conducted to test the hypothesis that whole brain radiation following surgical removal improves the quality of life and the survival time in patients with cerebral metastasis. From January 1, 1994 to December 31, 2000, a total of 139 patients (mean age 59 +/- 2.3 years, m : f = 84 : 55) with cerebral metastases were investigated. Disease-related living conditions were assessed by Karnofsky score, the median time of follow-up was 11 months. For the analysis, patients were divided into groups with and without radiation therapy. Additionally, groups of patients with singular and two brain metastases were defined. In patients with singular brain metastases neither the survival time nor disease-related living conditions during the remaining life time was increased by postoperative whole brain irradiation. Almost all patients died due to the progression of the primary tumor. Patients with more than one metastases seemed to have a slight but not significant benefit from irradiation therapy after surgical removal of all metastases. In conclusion, these results indicate that an uncritical irradiation therapy of neurocranium after surgical removal of cerebral metastases is not beneficial in terms of survival time or disease-related living conditions.

Cyclic mechanical stretching enhances secretion of Interleukin 6 in human tendon fibroblasts.

Accelerated rehabilitation after tendon and ligament injuries is widely accepted to avoid adverse effects of immobilization. However, progressive rehabilitation may also lead to an excessive inflammatory soft tissue response. To investigate the amount of loading necessary to accelerate the healing process without causing damage to the healing tissue, we experimentally stretched human tendon fibroblasts of healthy tendons 15 and 60 min with 1 Hz and an elongation of 5% and measured the secretion of interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-alpha), transforming growth factor beta1 (TGF-beta1), platelet-derived growth factor (PDGF), and fibroblast growth factor basic (bFGF). Secretion of IL-6 was significantly induced by 15 min of cyclic biaxial mechanical stretching after 4 and 8 h observation time and by 60 min stretching and 2 h observation time. The growth factors TGF-beta1, bFGF, and PDGF were secreted by human tendon fibroblasts both in stretched cells and controls; however, no increases were related to mechanical stretching. There was no measurable secretion of TNF-alpha in human tendon fibroblasts. These findings suggest that the inflammatory reaction often seen during physiotherapy after tendon and ligament injuries is caused in part by secretion of IL-6 from the stretched human tendon fibroblasts. IL-6 may cause exaggerated proliferation of fibroblasts and synovial cells as seen in rheumatoid arthritis and arthrofibrosis. However, physiological proliferative reactions leading to repair of injured tissue are also possible. IL-6 measured in the synovial fluid may be an important predictor for monitoring and improving therapeutic strategies in terms of tendon/ligament healing.

The effect of trauma on neutrophil L-selectin expression and sL-selectin serum levels.

Among identified adhesion molecules, the L-selectin on neutrophils enables the first step of leukocyte adherence to activated endothelial cells. To allow firm adhesion of neutrophils, L-selectin is then split off the cell membrane. It was hypothetized that an increase of the constitutively high serum level of soluble L-selectin may indicate an ongoing pathological neutrophil sequestration to the endothelial cells associated with activation and injury of the cells. To evaluate this hypothesis, sL-selectin serum levels and neutrophil L-selectin expression of healthy volunteers (group A, n = 15), as well as of surgical patients, were investigated. Group B (n = 26) included patients subjected to elective limb surgery (mean operation time, 122 min), and group C (n = 45) comprised trauma patients. sL-selectin serum levels were measured daily over a 14-day period. Neutrophil L-selectin expression was evaluated by FACS analysis using the humanized anti-L-selectin antibody HuDreg 55 over a period of 3 days at minimum in both experimental groups. The binding of sL-selectin to endothelial cells was also examined in vitro. Elective limb surgery resulted in lower pre- and post-operative sL-selectin plasma levels (800-1,000 ng/mL) compared to healthy volunteers (1,100-1,200 ng/mL) with insignificant changes throughout the study period. Trauma patients revealed even lower sL-selectin levels (400-600 ng/mL). When these patients were discriminated by the multiple organ dysfunction (MOD) score of Moore in +MOD (n = 9, ISS = 31.7) and -MOD (n = 36, ISS = 25.0), a significant difference became evident. In +MOD patients sL-selectin levels remained on a low basis of 350 ng/mL, whereas in -MOD patients the initial low sL-selectin level subsequently rose to 800 ng/mL, similar to that of elective surgery patients. FACS analysis revealed a significant drop in neutrophil L-selectin expression 24 h after trauma compared to normal. Also, +MOD and -MOD patients were significantly discriminated by the L-selectin expression at this time. The in vitro studies revealed evidence for binding of sL-selectin to endothelial cells independently on the presence of neutrophils. According to our data, increasing severity of the post-operative/posttraumatic course is associated with decreasing sL-selectin serum levels and also reduced neutrophil L-selectin expression. In view of the in vitro results, this probably indicates competitive enhanced binding of sL-selectin to endothelial cells, thus masking the elevated activation of neutrophils and their ability for endothelial adherence.

Cyclic mechanical stretching modulates secretion pattern of growth factors in human tendon fibroblasts.

The objective of the study was to investigate whether the response profile of the growth factor of human tendon fibroblasts could be beneficially influenced through the application of mechanical stretch. It was considered that this would elucidate structural and functional problems, often seen after tendon and ligament healing. The secretion pattern of transforming growth factor-beta (TGF-beta), platelet-derived growth factor (PDGF) and basic fibroblast growth factor (bFGF) was determined in mechanically stretched fibroblasts and compared to non-stretched controls. Human tendon fibroblasts were experimentally stretched for 15 and 60 mm at a frequency of 1 Hz and an amplitude of 5%. The secretion of TGF-beta PDGF and bFGF was measured by enzyme-linked immuno-sorbent assay. All the growth factors investigated were indeed secreted by human tendon fibroblasts both in stretched cells and controls. Mechanical stretch increased the secretion pattern of the growth factors. The increased concentrations of TGF-beta bFGF and PDGF after cyclical mechanical stretching may have a positive influence on tendon and ligament healing through stimulation of cell proliferation, differentiation and matrix formation.

Predicting cost-benefits before programs are started: looking at conjugate vaccine for invasive pneumococcal infections.

This analysis uses existing data to examine how an analysis to predict the net financial impact for an emerging medical program, namely a conjugate vaccine against Streptococcus pneumoniae, and to identify which key variables will have the greatest impact on the program's costs and benefits. Using data available on the prevalence and case fatality rates for invasive diseases caused by S pneumoniae, we examined the theoretical economic impact of vaccinating all newborns versus not vaccinating. Effectiveness estimates for conjugated pneumococcal vaccines and disease incidence and fatality rates were obtained from published sources. Because of scanty or inconclusive data for otitis media and pneumonia, the analysis was limited to cases of meningitis and bacteremia due to S pneumoniae. Based on these two diseases alone, immunization with conjugate pneumococcal vaccine could save an estimated 222 lives per million children vaccinated per year. Analysis of direct costs (projected immunization costs minus savings from reduced illness) show that a pneumococcal vaccine program will result in net direct costs between $0.08 and $2.42 per child. When indirect costs are included in the analysis, the vaccine is cost savings for all cases except when the two year incidence of disease and death rates are lowest and the cost of the vaccine series is $150. Further research should focus on these key issues as the vaccine is introduced into use, as expected in the next few years.

Evaluation and treatment of respiratory infections: does managed care make a difference?

BACKGROUND: Primary care physicians frequently use antibiotics for nonindicated conditions and conditions for which antibiotics have not been shown to be effective. The intention of this study was to determine whether shifting the costs from the insurer to physicians in a staff model health maintenance organization (HMO) influenced antibiotic prescribing. METHODS: A random sample of patients in whom upper respiratory infections (URIs) (n = 334) or acute bronchitis (n = 218) were diagnosed within a 12-month period was selected from a large multispecialty group practice whose population was predominantly fee-for-service (FFS) and from a staff model HMO. Detailed chart reviews were performed to verify the diagnosis and note secondary diagnoses, identify whether an antibiotic or other medication was prescribed, assess whether diagnostic testing was performed, and determine the specialty of the clinician. RESULTS: After excluding patients seen with sinusitis, otitis media, or streptococcal pharyngitis, 334 patients with URIs and 218 patients with acute bronchitis remained for analysis. For URIs, antibiotic prescribing was higher in the HMO population than in the FFS group (31% vs 20%, P = .02). In patients with acute bronchitis, HMO patients were also more likely to have an antibiotic prescribed, but the difference was not statistically significant (82% vs 73%, P = .11). Further analyses showed that while HMO physicians were more likely to prescribe antibiotics, they were less likely to prescribe other medications for acute bronchitis or use diagnostic tests for evaluation of patients with URIs or bronchitis. CONCLUSIONS: Shifting costs from insurer to physicians through managed care appears to reduce diagnostic testing for URIs and acute bronchitis, but does not decrease excessive use of antibiotics and may actually increase antibiotic use for URIs.