158 research outputs found
TIME RESOLVED DYNAMICS OF ELECTRONIC EXCITATIONS IN
No full text S. Minemoto, J. M\""{u}ller, G. Gantef\""{o}r, H. J. M\""{u}nzer, J. Boneberg, and P. Leiderer, Phys. Rev. Lett. accepted for publicationAuthor Institution: Universit\""at KonstanzExperiments have been performed an the ultrafast electron dynamics of mass selected cluster anions. The setup consists of a pulsed arc cluster ion source (PACIS), a time-of-flight mass spectrometer, a magnetic-bottle-type time of flight electron spectrometer, and a femtosecond laser. Time resolved pump/probe photoelectron spectra are recorded. We present first data on . Photoelectron spectra were obtained for a set of increasing delays between pump pulse (excitation of the anion) and probe pulse (detachment of the ad-electron). Interpretation of the series of spectra yields an assignment of the involved electron states and, moreover, the lifetime of the excited state. The method is suitable to study all kinds of electronic excitation and relaxation processes in mass selected nanoparticles. [FIGURE
The extremely truncated circumstellar disc of V410 X-ray 1: A precursor to TRAPPIST-1?
No full textProtoplanetary discs around brown dwarfs and very low mass (VLM) stars offer some of the best prospects for forming Earth-sized planets in their habitable zones. To this end, we study the nature of the disc around the VLM star V410 X-ray 1, whose spectral energy distribution (SED) is indicative of an optically thick and very truncated dust disc, with our modelling suggesting an outer radius of only 0.6 au. We investigate two scenarios that could lead to such a truncation, and find that the observed SED is compatible with both. The first scenario involves the truncation of both the dust and gas in the disc, perhaps due to a previous dynamical interaction or the presence of an undetected companion. The second scenario involves the fact that a radial location of 0.6 au is close to the expected location of the H2O snowline in the disc. As such, a combination of efficient dust growth, radial migration, and subsequent fragmentation within the snowline leads to an optically thick inner dust disc and larger, optically thin outer dust disc. We find that a firm measurement of the CO J = 2-1 line flux would enable us to distinguish between these two scenarios, by enabling a measurement of the radial extent of gas in the disc.Many models we consider contain at least several Earth-masses of dust interior to 0.6 au, suggesting that V410 X-ray 1 could be a precursor to a system with tightly packed inner planets, such as TRAPPIST-1
Superhard, conductive coatings for atomic force microscopy cantilevers
No full textBoron carbide thin films were grown by mass selected ion beam deposition using low energy 11B+ and 12C+ ions at room temperature. The amorphous films exhibit any desired stoichiometry controlled by the ion charge ratio B+/C+. Films with a stoichiometry of B4C showed the optimal combination of a high mechanical strength and a low electrical resistivity for the coating of atomic force microscopy (AFM) silicon cantilevers. The properties of such AFM tips were evaluated and simultaneous topography and Kelvin mode AFM measurements with high lateral resolution were performed on the systems (i) Au nanoparticles on a p-WS2 surface and (ii) conducting/ superconducting YBa2Cu3O72x.publishe
Localized Crystallization of Calcium Phosphates by Light-Induced Processes
No full textMedical treatment options for bones and teeth can be significantly enhanced by taking control over the crystallization of biomaterials like hydroxyapatite in the healing process. Light-induced techniques are particularly interesting for this approach as they offer tremendous accuracy in spatial resolution. However, in the field of calcium phosphates, light-induced crystallization has not been investigated so far. Here, proof of principle is established to successfully induce carbonate-hydroxyapatite precipitation by light irradiation. Phosphoric acid is released by a photolabile molecule exclusively after irradiation, combining with calcium ions to form a calcium phosphate in the crystallization medium. 4-Nitrophenylphosphate (4NPP) is established as the photolabile molecule and the system is optimized and fully characterized. A calcium phosphate is crystallized exclusively by irradiation in aqueous solution and identified as carbonate apatite. Control over the localization and stabilization of the carbonate apatite is achieved by a pulsed laser, triggering precipitation in calcium and 4NPP-containing gel matrices. The results of this communication open up a wide range of new opportunities, both in the field of chemistry for more sophisticated reaction control in localized crystallization processes and in the field of medicine for enhanced treatment of calcium phosphate containing biomaterials
Flotillins are involved in the polarization of primitive and mature hematopoietic cells
No full textBACKGROUND: Migration of mature and immature leukocytes in response to chemokines is not only essential during inflammation and host defense, but also during development of the hematopoietic system. Many molecules implicated in migratory polarity show uniform cellular distribution under non-activated conditions, but acquire a polarized localization upon exposure to migratory cues. METHODOLOGY/PRINCIPAL FINDINGS: Here, we present evidence that raft-associated endocytic proteins (flotillins) are pre-assembled in lymphoid, myeloid and primitive hematopoietic cells and accumulate in the uropod during migration. Furthermore, flotillins display a polarized distribution during immunological synapse formation. Employing the membrane lipid-order sensitive probe Laurdan, we show that flotillin accumulation in the immunological synapse is concomittant with membrane ordering in these regions. CONCLUSIONS: Together with the observation that flotillin polarization does not occur in other polarized cell types such as polarized epithelial cells, our results suggest a specific role for flotillins in hematopoietic cell polarization. Based on our results, we propose that in hematopoietic cells, flotillins provide intrinsic cues that govern segregation of certain microdomain-associated molecules during immune cell polarization
Intraoperative Komplikationen bei der ureterorenoskopischen Steintherapie in Abhängigkeit eines Pre-Stenting
No full textHintergrund, Ziele und Methode: Das Harnsteinleiden stellt ein Krankheitsbild mit steigender Inzidenz dar, das bei einer Harnleiterpassage des Steins durch kolikartige Schmerzen zu häufiger Hospitalisierung mit Bedarf einer interventionellen Maßnahme führt. Hierbei steht unter anderem die Ureterorenoskopie zur Verfügung, die trotz hoher klinischer Sicherheit mit intraoperativen Komplikationen vergesellschaftet sein kann. Dazu zählen sowohl kleinere intraoperative Komplikationen wie Perforationen des Ureters, Verletzung der Ureterschleimhaut gefolgt von einer Blutung, als auch schwerwiegende Komplikationen wie beispielsweise ein Abriss des Ureters. Bereits in der Vergangenheit wurde untersucht, wie sich die präoperative Einlage einer Ureterschiene auf verschiedene Kriterien, unter anderem auch auf intraoperative Komplikationen, auswirkt. Hierbei zeigt die Studienlage ein heterogenes Bild. In diesem Zusammenhang stellt sich die Frage, ob ein präoperatives Stenting einen Benefit für das Outcome der Ureterorensokopie bringt. In der vorliegenden Arbeit wird diese Frage mit Hilfe von Patientendaten retrospektiv genauer analysiert. Für die Arbeit wurden Patienten selektiert, die sich im Zeitraum zwischen 01.01.2014 – 31.12.2014 mit einem Harnsteinleiden in der Klinik für Urologie des Universitätsklinikums Gießen und Marburg (Standort Marburg) vorstellten. Der Therapieerfolg sowie die Komplikationsraten wurden hierbei zwischen zwei Gruppen verglichen. Die Patienten der einen Gruppe erhielten vor dem endoskopischen Eingriff ein Pre-Stenting (90 Fälle), wohingegen bei den Patienten der anderen Gruppe keine Harnleiterschiene vor der Ureterorensokopie eingelegt wurde (57 Fälle).
Ergebnisse: Die Ergebnisse dieser Studie zeigen sowohl positive als auch negative Effekte durch das Pre-Stenting vor einer geplanten Ureterorenoskopie. Zu den positiven Effekten gehören beispielsweise eine signifikante Abnahme der Patienten mit einer Hämaturie und Nierenbeckenektasie bei stationärer Aufnahme mit Pre-Stenting. Auch der Anteil an Patienten mit kolikartigen Beschwerden wird durch ein Pre-Stenting gesenkt. Weiterhin führt die Anlage der Schiene zu einer signifikanten Verminderung der Einnahme von Spasmoanalgetika (z.B. Metamizol) und Alpha-Rezeptorblockern (Tamsulosin) während des stationären Aufenthaltes. Auch für den intraoperativen Verlauf können positive Effekte, wie die signifikante Abnahme an Bougierungen der Harnwege bei Patienten mit Pre-Stenting beobachtet werden. Auf der anderen Seite treten intraoperative Kompli-kationen signifikant häufiger in der Gruppe mit Pre-Stenting auf. Besonders für Harnleiterläsionen und intraoperative Blutungen ist ein signifikanter, bei letzterem ein hochsignifikanter Unterschied zu erkennen. Zudem zeigt sich bei Patienten mit liegender Harnleiterschiene signifikant häufiger eine bewachsene Urinkultur.
Diskussion und Schlussfolgerung: Das Hauptthema dieser Arbeit zielt auf die Frage ab, inwiefern sich ein Pre-Stenting auf die intraoperativen Komplikationen einer Stein-URS auswirkt. Dabei ist festzustellen, dass intraoperative Komplikationen in dieser Studie nur selten festgestellt werden konnten, allerdings fast ausschließlich in der Gruppe mit Pre-Stenting. Nach den Ergebnissen dieser Arbeit scheint das Legen einer Harnleiterschiene vor der geplanten Ureterorenoskopie zwar zu einer Erleichterung der OP-Bedingungen zu führen. Es zeigt sich eine Verringerung der Rate an Bougierungen der Harnwege, sowie eine Abnahme des Anteils an impaktierten Steinen. Zusätzlich kann häufiger ein flexibles Ureterorensokop bei Patienten mit Pre-Stenting verwendet werden. Dies kann auch durch eine vergleichbare Studie bestätigt werden (Navetta et al. 2019). Eine weitere Studie zeigt allerdings keine signifikante Verbesserung durch das Pre-Stenting unabhängig von der Lokalisation bzw. Steingröße bezüglich der Komplikationsrate (Dessyn et al. 2016). Zusammenfassend ist daher festzustellen, dass trotz der oben beschriebenen positiven Effekte eines Pre-Stentings aufgrund der erhöhten intraoperativen Komplikationen die Indikation zur Einlage einer Harn-leiterschiene vor geplanter Ureterorensoskopie wie bisher grundsätzlich nur nach den Vorgaben der entsprechenden Leitlinie gestellt werden sollte und Ausnahmen einer sorgfältigen Risikoabwägung im Sinne des Patienten bedürfen.Background, aims and methods: Urolithiasis and nephrolithiasis are clinical pictures with increasing incidence, which lead to frequent hospitalization requiring interventional measures due to colicky pain, associated with an obstruction of the ureter. Ureterorenoscopy is available as a standard treatment, which can however be associated with intraoperative complications despite high clinical safety. These include minor intraoperative complications such as perforation of the ureter, injury of the ureteral mucosa followed by bleeding as well as major complications such as a rupture or invagination of the ureter. Previous studies have addressed the question as to how the preoperative insertion of a ureteral stent affects various criteria including intraoperative complications. However, these studies show a heterogeneous picture. In this context the question arises as to what extent preoperative stenting provides a benefit for the outcome of the ureterorenoscopy. In the present work, this is retrospectively analyzed in more detail with the help of patient data. For the study patients presenting to the clinic for urology and pediatric urology of the University Hospital Gießen and Marburg (Marburg site) in the period between 1 January 2014 and 31 December 2014 with a urinary stone were selected. In order to improve the informative value of the data for the present study the patients were divided into two large groups. In order to be able to work on the main topic of this work more precisely the patients were divided into two large groups. The first group received pre-stenting before the endoscopic intervention (90 cases) whereas the second group did not receive a ureteral stent before the ureterorenoscopy (57 cases).
Results: The results of this study show both positive and negative effects of pre-stenting before a planned ureterorenoscopy. For example, a significant decrease in the number of patients with haematuria and renal pelvic ectasia was observed in patients with pre-stenting. Pre-stenting also reduces the fraction of patients with colicky symptoms. Furthermore, the application of a ureteral stent leads to a significant reduction in the intake of spasm analgesics such as metamizole and alpha-receptor blockers (tamsulosin) during the inpatient stay. Positive effects, such as the significant reduction in bougienage of the urinary tract in patients with pre-stenting can also be observed during the intraoperative course. On the other hand intraoperative complications are significantly more common in the pre-stented group. A significant difference can be seen concerning especially ureter lesions and intraoperative bleeding. The proportion of detection of various germs in the urine during hospital admission is also significantly higher in patients with a ureteral stent.
Discussion and conclusions: The main question addressed in this study is how pre-stenting affects intraoperative complications of ureterorenoscopy. It should be noted that intraoperative complications were only rarely observed in this study, but almost exclusively in the group with pre-stenting. According to the results of this work, the placement of a ureteral stent before the planned ureterorenoscopy can potentially lead to an improvement in the surgical conditions. There is a reduction in the rate of urinary tract bulging and a decrease in the fraction of impacted stones. In addition, a flexible ureteral scope can be used more frequently in patients with pre-stenting. This is also confirmed by a comparable study (Navetta et al. 2019). However, another study shows no significant improvement regarding the complication rate by pre-stenting regardless of the location or stone size (Dessyn et al. 2016). However, another study shows no significant improvement for pre-stenting regardless of the location or stone size with regard to the complication rate (Dessyn et al. 2016). In summary, it can therefore be stated that despite the positive effects of pre-stenting, increased intraoperative complications imply that the indication for the insertion of a ureteral stent before an ureterorenoscopy should only be made according to the specifications of the cor-responding guideline. For this reason exceptions require a careful risk assessment in the interest of the patient
Angiogenesis and lymphangiogenesis are downregulated in primary breast cancer
No full textAngiogenesis and lymphangiogenesis are considered to play key roles in tumour growth, progression and metastasis. However, targeting tumour angiogenesis in clinical trials showed only modest efficacy. We therefore scrutinised the concept of tumour angiogenesis and lymphangiogenesis by analysing the expression of crucial markers involved in these processes in primary breast cancer.
Methods: We analysed the expression of angiogenic, lymphangiogenic or antiangiogenic factors, their respective receptors and specific markers for endothelial and lymphendothelial cells by quantitative real-time RT-PCR in primary breast cancer and compared the expression profiles to non-cancerous, tumour-adjacent tissues and breast tissues from healthy women.
Results: We found decreased mRNA amounts of major angiogenic and lymphangiogenic factors in tumour compared to healthy tissues, whereas antiangiogenic factors were upregulated. Concomitantly, angiogenic and lymphangiogenic receptors were downregulated in breast tumours. This antiangiogenic, antilymphangiogenic microenvironment was even more pronounced in aggressive tumours and accompanied by reduced amounts of endothelial and lymphatic endothelial cell markers.
Conclusion: Primary breast tumours are not a site of highly active angiogenesis and lymphangiogenesis. Selection for tumour cells that survive with minimal vascular supply may account for this observation in clinical apparent tumours
Single-crystalline YIG flakes with uniaxial in-plane anisotropy and diverse crystallographic orientations
No full textWe study Y3Fe5O12 (YIG) flakes that we produce via mechanical cleaving and
exfoliation of YIG single crystals. By characterizing their structural and
magnetic properties, we find that these YIG nanoflakes have surfaces oriented
along unusual crystallographic axes and uniaxial in-plane magnetic anisotropy
due to their shape, both of which are not commonly available in YIG thin films.
These physical properties, combined with the possibility of picking up the YIG
flakes and stacking them onto flakes of other van der Waals materials or
pre-patterned electrodes or waveguides, open unexplored possibilities for
magnonics and for the realization of novel YIG-based heterostructures and
devices.Comment: 13 pages, 4 figure
Local field enhancement effects for nanostructuring of surfaces
No full textWe report on a method that allows the nanostructuring of surfaces with intense laser pulses. For this purpose isolated polystyrene spheres with diameters in the order of the laser wavelength were deposited on a silicon or glass surface. Illumination with short and ultrashort laser pulses produced holes underneath these particles. Calculations of the field near the particles make clear that geometrical optics, that is, focusing by a spherical lens, as well as near-field effects, contribute to the size and shape of these holes. This technique can be utilized for the parallel structuring of large surface areas with a single laser shot.publishe
Is conceptual vagueness an asset? Resilience research from the perspective of philosophy of science
No full textI analyze the research on social-ecological resilience from the perspective of philosophy of science in three steps. First, I explore to what degree resilience research exhibits conceptual vagueness. I find a wide spectrum of research, ranging from approaches relying on a concise conceptual framework to the perspective of “resilience thinking”, which builds on a cluster of vague concepts. Second, I set out the methodological arguments in favor and against conceptual vagueness. Merging both strands of reasoning in the third step, I conclude that a trade-off between vagueness and precision exists, which is to be solved differently depending on the context of resilience research. In some contexts, resilience research benefits from conceptual vagueness while in others it depends on precision. Specifically, I argue that in “resilience thinking” the trade-off might be enhanced by a coherent restructuring of the conceptual framework.vagueness, philosophy of science, precision, resilience thinking, socialecological systems
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