An experiment to detect gravity at sub-mm scale with high-Q mechanical oscillators

Silicon double paddle oscillators are well suited for the detection of weak forces because of their high Q factor (about 10^5 at room temperature). We describe an experiment aimed at the detection of gravitational forces between masses at sub-mm distance using such an oscillator. Gravitational excitation is produced by a rotating aluminium disk with platinum segments. The force sensitivity of this apparatus is about 10 fN at room temperature for 1000 s averaging time at room temperature. The current limitations to detection of the gravitational force are mentioned.Comment: 19 pages, to appear in Proceedings of the Tenth Marcel Grossmann Meeting on General Relativity, edited by M. Novello, S. Perez-Bergliaffa and R. Ruffini, World Scientific. Revision: portable format and revised figure

Untersuchung zur Genauigkeit verschiedener Abformmethoden in Kombination verschiedener Abformmaterialien bei Verwendung des Brånemark®-Implant-Systems

Im Laufe der letzten zwanzig Jahre hat sich die orale, enossale Implantologie zu einem anerkannten Therapieverfahren entwickelt. Die Anzahl der implantatprothetisch versorgten Patienten nimmt stetig zu. Um diese hochwertigen Versorgungen herzustellen bedarf es eines Höchstmaßes an Präzision eines jeden Arbeitsschrittes, wobei die Abdrucknahme und die Herstellung von Präzisionsmodellen zentrale Punkte bei der Anfertigung dauerhafter Versorgungen sind. Ziel der vorliegenden Arbeit war deshalb die Untersuchung der Genauigkeit verschiedener Abformtechniken mittels unterschiedlicher Abformmaterialien bei Verwendung des Brånemark®-Implantat-systems, indem sowohl die hergestellten Modelle als auch die Abformungen vermessen wurden. Auf der Basis eines simulierten Patientenfalles wurde ein Kunststoffmodell mit fünf parallel inserierten Brånemark®-Implantaten hergestellt. Um dieses Modell reproduzierbar abzuformen, kam eine speziell entwickelte Abformvorrichtung zur Anwendung. Dieselbe Apparatur wurde zusätzlich für die Modellherstellung verwendet. Folgende Techniken und Materialien wurden untersucht: 1. Geschlossene Abformtechnik (Pfosten wird reponiert) mit den Materialien Monopren® transfer und Provil® P / M.C.D. (Doppelmisch- und Korrekturtechnik) 2. Offene Abformtechnik (Pfosten verbleibt in Abformung) mit den Materialien Impregum®, Baysilex® C.D., Monopren® transfer und Provil® P / M.C.D (Doppelmischtechnik) Es wurden mit jeder Material/Technikkombination fünf Abformungen und fünf Modelle hergestellt. Die verwendeten Abformpfosten und Modellimplantate wurden innerhalb der Versuchsreihe wiederverwendet. Die Implantatabstände wurden in zehn Messstrecken unterteilt und in der Horizontalebene mittels eines elektronischen Messmikroskops TP 300 der Firma Leitz mit einer Genauigkeit von ±7 µm ermittelt. Vermessen wurden die Abformungen vor der Modellherstellung sowie die hergestellten Superhartgipsmodelle. Die geringsten Abweichungen entstanden bei den Abformungen bei den monophasigen Materialien unter Anwendung der offenen Abformtechnik, die höchsten Abweichungen bei Monopren/geschlossen sowie bei Provil K/geschlossen. Es ergaben sich für die Abformungen mit der offenen Technik signifikant präzisere Reproduktionen des Urmodells. Ein ähnliches Bild zeigt sich für die Wiedergabe der Messstrecken der Modelle. Der gewählte Ansatz der Untersuchung sah eine Vermessung von Abformungen und Modellen vor, erlaubte somit eine genaue Analyse des entstandenen Fehlers und ermöglichte Rückschlüsse darüber, ob Fehler, die durch die Abformung entstanden waren, auf dem Modell reproduziert wurden, oder ob die Fehler der Modelle unabhängig von denjenigen der Abformungen auftraten. Die durchgeführte Korrelationsanalyse ergab eine höchst signifikante mittlere Korrelation für die Kombinationen Impregum offen (r = 0,501***) und alle geschlossenen Kombinationen (r = 0,514*** – 0,634***). Es wurde weiterhin untersucht, ob bei mehrfacher Verwendung der Übertragungsaufbauten und Modellimplantate die Präzision der ermittelten Werte abnimmt. Bei viermaliger Wiederverwendung dieser Implantatteile konnte keine signifikante Abnahme der Übertragungsgenauigkeit festgestellt werden

Quick X-ray microtomography using a laser-driven betatron source

Laser-driven X-ray sources are an emerging alternative to conventional X-ray tubes and synchrotron sources. We present results on microtomographic X-ray imaging of a cancellous human bone sample using synchrotron-like betatron radiation. The source is driven by a 100-TW-class titanium-sapphire laser system and delivers over $10^8$ X-ray photons per second. Compared to earlier studies, the acquisition time for an entire tomographic dataset has been reduced by more than an order of magnitude. Additionally, the reconstruction quality benefits from the use of statistical iterative reconstruction techniques. Depending on the desired resolution, tomographies are thereby acquired within minutes, which is an important milestone towards real-life applications of laser-plasma X-ray sources

GMFilter and SXTestPlate: software tools for improving the SNPlex™ genotyping system

<p>Abstract</p> <p>Background</p> <p>Genotyping of single-nucleotide polymorphisms (SNPs) is a fundamental technology in modern genetics. The SNPlex™ mid-throughput genotyping system (Applied Biosystems, Foster City, CA, USA) enables the multiplexed genotyping of up to 48 SNPs simultaneously in a single DNA sample. The high level of automation and the large amount of data produced in a high-throughput laboratory require advanced software tools for quality control and workflow management.</p> <p>Results</p> <p>We have developed two programs, which address two main aspects of quality control in a SNPlex™ genotyping environment: GMFilter improves the analysis of SNPlex™ plates by removing wells with a low overall signal intensity. It enables scientists to automatically process the raw data in a standardized way before analyzing a plate with the proprietary GeneMapper software from Applied Biosystems. SXTestPlate examines the genotype concordance of a SNPlex™ test plate, which was typed with a control SNP set. This program allows for regular quality control checks of a SNPlex™ genotyping platform. It is compatible to other genotyping methods as well.</p> <p>Conclusion</p> <p>GMFilter and SXTestPlate provide a valuable tool set for laboratories engaged in genotyping based on the SNPlex™ system. The programs enhance the analysis of SNPlex™ plates with the GeneMapper software and enable scientists to evaluate the performance of their genotyping platform.</p

Quantification and Assessment of Interfraction Setup Errors Based on Cone Beam CT and Determination of Safety Margins for Radiotherapy

Introduction To quantify interfraction patient setup-errors for radiotherapy based on cone-beam computed tomography and suggest safety margins accordingly. Material and Methods Positioning vectors of pre-treatment cone-beam computed tomography for different treatment sites were collected (n = 9504). For each patient group the total average and standard deviation were calculated and the overall mean, systematic and random errors as well as safety margins were determined Results The systematic (and random errors) in the superior-inferior, left-right and anterior-posterior directions were: for prostate, 2.5(3.0), 2.6(3.9) and 2.9(3.9) mm; for prostate bed, 1.7(2.0), 2.2(3.6) and 2.6(3.1) mm; for cervix, 2.8(3.4), 2.3(4.6) and 3.2(3.9) mm; for rectum, 1.6(3.1), 2.1(2.9) and 2.5(3.8) mm; for anal, 1.7(3.7), 2.1(5.1) and 2.5(4.8) mm; for head and neck, 1.9(2.3), 1.4(2.0) and 1.7(2.2) mm; for brain, 1.0(1.5), 1.1(1.4) and 1.0(1.1) mm; and for mediastinum, 3.3(4.6), 2.6(3.7) and 3.5(4.0) mm. The CTV-to-PTV margins had the smallest value for brain (3.6, 3.7 and 3.3mm) and the largest for mediastinum (11.5, 9.1 and 11.6mm). For pelvic treatments the means (and standard deviations) were 7.3 (1.6), 8.5 (0.8) and 9.6 (0.8) mm. Conclusions Systematic and random setup-errors were smaller than 5mm. The largest errors were found for organs with higher motion probability. The suggested safety margins were comparable to published values in previous but often smaller studies

Density profiles and density oscillations of an interacting three-component normal Fermi gas

We use a semiclassical approximation to investigate density variations and dipole oscillations of an interacting three-component normal Fermi gas in a harmonic trap. We consider both attractive and repulsive interactions between different pairs of fermions and study the effect of population imbalance on densities. We find that the density profiles significantly deviate from those of non-interacting profiles and extremely sensitive to interactions and population imbalance. Unlike for a two-component Fermi system, we find density imbalance even for balanced populations. For some range of parameters, one component completely repels from the trap center giving rise a donut shape density profile. Further, we find that the in-phase dipole oscillation frequency is consistent with Kohn's theorem and other two dipole mode frequencies are strongly effected by the interactions and the number of atoms in the harmonic trap.Comment: Total seven pages with five figures. Published versio

Synthesis and in vitro evaluation of cyclodextrin hyaluronic acid conjugates as a new candidate for intestinal drug carrier for steroid hormones

Steroid hormones became increasingly interesting as active pharmaceutical ingredients for the treatment of endocrine disorders. However, medical applications of many steroidal drugs are inhibited by their very low aqueous solubilities giving rise to low bioavailabilities. Therefore, the prioritized oral administration of steroidal drugs remains problematic. Cyclodextrins are promising candidates for the development of drug delivery systems for oral route applications, since they solubilize hydrophobic steroids and increase their rate of transport in aqueous environments. In this study, the synthesis and characterization of polymeric β-cyclodextrin derivates is described, which result from the attachment of a hydrophilic β-CD-thioether to hyaluronic acid. Host-guest complexes of the synthesized β-cyclodextrin hyaluronic acid conjugates were formed with two poorly soluble model steroids (β-estradiol, dexamethasone) and compared to monomeric β-cyclodextrin derivates regarding solubilization and complexation efficiency. The β-cyclodextrin-drug (host-guest) complexes were evaluated in vitro for their suitability (cytotoxicity and transport rate) as intestinal drug carriers for steroid hormones. In case of β-estradiol, higher solubilities could be achieved by complexation with both synthesized β-cyclodextrin derivates, leading to significantly higher intestinal transport rates in vitro. However, this success could not be shown for dexamethasone, which namely solubilized better, but could not enhance the transport rate significantly. Thus, this study demonstrates the biocompatibility of the synthesized and characterized β-cyclodextrin derivates and shows their potential as new candidate for intestinal drug carrier for steroid hormones like β-estradiol

Radiotherapy for tumors of the stomach and gastroesophageal junction - a review of its role in multimodal therapy

There is broad consensus on surgical resection being the backbone of curative therapy of gastric- and gastroesophageal junction carcinoma. Nevertheless, details on therapeutic approaches in addition to surgery, such as chemotherapy, radiotherapy or radiochemotherapy are discussed controversially; especially whether external beam radiotherapy should be applied in addition to chemotherapy and surgery is debated in both entities and differs widely between regions and centers. Early landmark trials such as the Intergroup-0116 and the MAGIC trial must be interpreted in the context of potentially insufficient lymph node resection. Despite shortcomings of both trials, benefits on overall survival by radiochemotherapy and adjuvant chemotherapy were confirmed in populations of D2-resected gastric cancer patients by Asian trials. Recent results on junctional carcinoma patients strongly suggest a survival benefit of neoadjuvant radiochemotherapy in curatively resectable patients. An effect of chemotherapy in the perioperative setting as given in the MAGIC study has been confirmed by the ACCORD07 trial for junctional carcinomas; however both the studies by Stahl et al. and the excellent outcome in the CROSS trial as compared to all other therapeutic approaches indicate a superiority of neoadjuvant radiochemotherapy as compared to perioperative chemotherapy in junctional carcinoma patients. Surgery alone without neoadjuvant or perioperative therapy is considered suboptimal in patients with locally advanced disease. In gastric carcinoma patients, perioperative chemotherapy has not been compared to adjuvant radiochemotherapy in a randomized setting. Nevertheless, the results of the recently published ARTIST trial and the Chinese data by Zhu and coworkers, indicate a superiority of adjuvant radiochemotherapy as compared to adjuvant chemotherapy in terms of disease free survival in Asian patients with advanced gastric carcinoma. The ongoing CRITICS trial is supposed to provide reliable conclusions about which therapy should be preferred in Western patients with gastric carcinoma. If radiotherapy is performed, modern approaches such as intensity-modulated radiotherapy and image guidance should be applied, as these methods reduce dose to organs at risk and provide a more homogenous coverage of planning target volumes