Experimental Observation of a Fundamental Length Scale of Waves in Random Media

Waves propagating through a weakly scattering random medium show a pronounced branching of the flow accompanied by the formation of freak waves, i.e., extremely intense waves. Theory predicts that this strong fluctuation regime is accompanied by its own fundamental length scale of transport in random media, parametrically different from the mean free path or the localization length. We show numerically how the scintillation index can be used to assess the scaling behavior of the branching length. We report the experimental observation of this scaling using microwave transport experiments in quasi-two-dimensional resonators with randomly distributed weak scatterers. Remarkably, the scaling range extends much further than expected from random caustics statistics.Comment: 5 pages, 5 figure

Osteosynthese distaler Radiusfrakturen mit der AO/ASIF Titan-Pi-Platte

Zusammenfassung: Die AO/ASIF Titan-Pi-Platte wurde entwickelt, um eine optimale Versorgung distaler, intraartikulärer und instabiler Radiusfrakturen zu gewährleisten. Dies soll durch eine optimale Anpassung an die Anatomie sowie durch Winkelstabilität und flachem Design erfolgen. Ziel der vorliegenden retrospektiven Fallkontrollstudie war es, die objektiven und subjektiven Resultate anhand einer konsekutiven Reihe von 61Patienten mindestens 12Monate (12-29Monate) postoperativ mittels Befragung, klinischer Untersuchung und konventioneller radiologischer Bildgebung zu erheben. Nach Klassifikation der AO handelte es sich um 3A2-, 23A3-, 1B1-, 12C1- und 22C2-Frakturen. Die Resultate zeigen insgesamt ein gutes bis sehr gutes Resultat bezüglich des subjektiven Befindens. Die Messungen des Bewegungsumfangs ergaben durchschnittlich über 80% im Vergleich zur Gegenseite. Die klinische Prüfung der Extensorensehnen ergab keine Rupturen und 18% Irritationen. Das Kollektiv mit Osteosynthesematerialentfernung zeigte einen signifikant größeren Bewegungsumfang der Extension und Ulnarabduktion, eine höhere Kraft sowie nur 3,8% Sehnenirritationen. Mit der Pi-Platte lassen sich gute subjektive und objektive Resultate erreichen. Aufgrund der signifikant besseren Beweglichkeit und höheren Kraft sowie der geringeren Rate an Sehnenirritationen nach Entfernung der Platte sollte die Indikation zur Osteosynthesematerialentfernung großzügig gestellt werde

Treatment of the Open Abdomen with the Commercially Available Vacuum-Assisted Closure System in Patients with Abdominal Sepsis: Low Primary Closure Rate

Background: Abdominal Vacuum-Assisted Closure (V.A.C.) systems for treatment of open abdomens have been predominantly used for trauma patients with a high primary fascial closure rate. Use of the V.A.C. technique in abdominal sepsis is less well established. Methods: All patients with abdominal sepsis and treatment with the abdominal V.A.C. system between 2004 and 2007 were prospectively assessed. End points were fascial closure, V.A.C.-related morbidity, and quality of life score (SF-36) at follow-up. Results: Thirty patients with abdominal sepsis were included in the study. Primary fascial closure was feasible in 10, partial closure in 4, and no closure in 16 patients. Median number of V.A.C. changes was 3 (range, 1-10). Nine patients died. V.A.C.-related morbidity was as follows: two fistulas, three fascial edge necroses, one skin blister, and four prolapses of small bowel between the fascia and foam. Univariate analysis showed no variables influencing primary closure rate or V.A.C.-related morbidity. Mortality was significantly influenced by age (P<0.001), respiratory failure (P=0.01), and pneumonia (P=0.03). At follow-up, V.A.C. patients scored lower in the physical health scores and similar in the mental health scores compared with the normal population. Conclusions: Treatment of the open abdomen in patients with abdominal sepsis with the abdominal V.A.C. system is safe with good long-term quality of life. Primary closure rate in these patients is substantially lower than in trauma patients. Stepwise closure of the fascia during V.A.C. changes should be attempted to avoid additional lateral retraction of fascial edges. V.A.C.-related complications may be avoided with careful surgical techniqu

Effect of bisacodyl on postoperative bowel motility in elective colorectal surgery: a prospective, randomized trial

Background: Postoperative ileus is a common condition after abdominal surgery. Many prokinetic drugs have been evaluated including osmotic laxatives. The data on colon-stimulating laxatives are scarce. This prospective, randomized, double-blind trial investigates the effect of the colon-stimulating laxative bisacodyl on postoperative ileus in elective colorectal resections. Materials and methods: Between November 2004 and February 2007, 200 consecutive patients were randomly assigned to receive either bisacodyl or placebo. Primary endpoint was time to gastrointestinal recovery (mean time to first flatus passed, first defecation, and first solid food tolerated; GI-3). Secondary endpoints were incidence and duration of nasogastric tube reinsertion, incidence of vomiting, length of hospital stay, and visual analogue scores for pain, cramps, and nausea. Results: One hundred sixty-nine patients were analyzed, and 31 patients discontinued the study. Groups were comparable in baseline demographics. Time to GI-3 was significantly shorter in the bisacodyl group (3.0 versus 3.7days, P = 0.007). Of the single parameters defining GI-3, there was a 1-day difference in time to defecation in favor to the bisacodyl group (3.0 versus 4.0days, P = 0.001), whereas no significant difference in time to first flatus or tolerance of solid food was seen. No significant difference in the secondary endpoints was seen. Morbidity and mortality did not differ between groups. Conclusion: Bisacodyl accelerated gastrointestinal recovery and might be considered as part of multimodal recovery programs after colorectal surger

Randomized controlled trial investigating the effect of music on the virtual reality laparoscopic learning performance of novice surgeons

Background: Findings have shown that music affects cognitive performance, but little is known about its influence on surgical performance. The hypothesis of this randomized controlled trial was that arousing (activating) music has a beneficial effect on the surgical performance of novice surgeons in the setting of a laparoscopic virtual reality task. Methods: For this study, 45 junior surgeons with no previous laparoscopic experience were randomly assigned to three equal groups. Group 1 listened to activating music; group 2 listened to deactivating music; and group 3 had no music (control) while each participant solved a surgical task five times on a virtual laparoscopic simulator. The assessed global task score, the total task time, the instrument travel distances, and the surgeons' heart rate were assessed. Results: All surgical performance parameters improved significantly with experience (task repetition). The global score showed a trend for a between-groups difference, suggesting that the group listening to activating music had the worst performance. This observation was supported by a significant between-groups difference for the first trial but not subsequent trials (activating music, 35 points; deactivating music, 66 points; no music, 91 points; p=0.002). The global score (p=0.056) and total task time (p=0.065) showed a trend toward improvement when participants considered the music pleasant rather than unpleasant. Conclusions: Music in the operating theater may have a distracting effect on novice surgeons performing new tasks. Surgical trainers should consider categorically switching off music during teaching procedure

Experimental Area of the CERN Antiproton Decelerator

The CERN Antiproton Decelerator will deliver low energy beams to four experimental beam-lines installed within the acceleratorcircumference. The limited space available imposes tight constraints on the topology of the beam-lines needed by the experimental devices. In this paper, the general layout of the experimental area is reviewed. Furthermore, a discussion of the so-called measurement line for tests and AD beam property measurements is included along with remarks on the optics of the reverse injection of protons, to be used for the commissioning

Three-dimensional diffraction mapping by tuning the X-ray energy

Three-dimensional reciprocal-space maps of a single SiGe island around the Si(004) Bragg peak are recorded using an energy-tuning technique with a microfocused X-ray beam with compound refractive lenses as focusing optics

The Magnetic Casimir Effect

The Casimir effect results from alterations of the zero-point electromagnetic energy introduced by boundary-conditions. For ferromagnetic layers separated by vacuum (or a dielectric) such boundary-conditions are influenced by the magneto-optical Kerr effect. We will show that this gives rise to a long-range magnetic interaction and discuss the effect for two different configurations (magnetization parallel and perpendicular to the layers). Analytical expressions are derived for two models and compared to numerical calculations. Numerical calculations of the effect for Fe are also presented and the possibility of an experimental observation of the Casimir magnetic interaction is discussed