Advanced geometries for ballistic neutron guides Schanzer, Christian; Böni, Peter; Filges, Uwe ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2004, Letnik:
529, Številka:
1
Journal Article
Recenzirano
Sophisticated neutron guide systems take advantage of supermirrors being used to increase the neutron flux. However, the finite reflectivity of supermirrors becomes a major loss mechanism when many ...reflections occur, e.g. in long neutron guides and for long wavelengths. In order to reduce the number of reflections, ballistic neutron guides have been proposed. Usually linear tapered sections are used to enlarge the cross-section and finally, focus the beam to the sample. The disadvantages of linear tapering are (i) an inhomogeneous phase space at the sample position and (ii) a decreasing flux with increasing distance from the exit of the guide. We investigate the properties of parabolic and elliptic tapering for ballistic neutron guides, using the Monte Carlo program McStas with a new guide component dedicated for such geometries. We show that the maximum flux can indeed be shifted away from the exit of the guide. In addition we explore the possibilities of parabolic and elliptic geometries to create point like sources for dedicated experimental demands.
Transglutaminases (TG) form a family of enzymes that catalyse various post-translational modifications of glutamine residues in proteins and peptides including intra- and intermolecular isopeptide ...bond formation, esterification and deamidation. We have characterized a novel member of the mammalian TG family, TG6, which is expressed in a human carcinoma cell line with neuronal characteristics and in mouse brain. Besides full-length protein, alternative splicing results in a short variant lacking the second β-barrel domain in man and a variant with truncated β-sandwich domain in mouse. Biochemical data show that TG6 is allosterically regulated by Ca
2+
and guanine nucleotides. Molecular modelling indicates that TG6 could have Ca
2+
and GDP-binding sites related to those of TG3 and TG2, respectively. Localization of mRNA and protein in the mouse identified abundant expression of TG6 in the central nervous system. Analysis of its temporal and spatial pattern of induction in mouse development indicates an association with neurogenesis. Neuronal expression of TG6 was confirmed by double-labelling of mouse forebrain cells with cell type-specific markers. Induction of differentiation in mouse Neuro 2a cells with NGF or dibutyryl cAMP is associated with an upregulation of TG6 expression. Familial ataxia has recently been linked to mutations in the TGM6 gene. Autoantibodies to TG6 were identified in immune-mediated ataxia in patients with gluten sensitivity. These findings suggest a critical role for TG6 in cortical and cerebellar neurons.
Abstract Objective Approximately 6% of breast cancer (BC) patients present with primary metastatic disease (pmBC) at first diagnosis. The clinicopathological differences between tumours from patients ...who have metastatic disease and those who do not are unclear. Methods This study was an exploratory analysis of patients with pmBC treated in 8 German breast cancer centres between 1998 and 2010. Phenotypes were defined using the following immunohistochemical markers: oestrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (Her2). The control arm included the group of patients who had neither local recurrence nor distant metastases at a follow-up of at least 30 months after initial diagnosis. Results A total of 2214 patients were included. Of these, 1642 had non metastatic BC, and 572 had pmBC. Eighty-five patients (15%) with pmBC were diagnosed at stage T1. On multivariate analysis, factors associated with pmBC were as follows: positive lymph node status, grade 3, lobular histology and Luminal B phenotype (Her 2 positive). Of the sample, 197 patients (34%) with pmBC were diagnosed as stage T2, 90 patients (16%) were diagnosed as stage T3, and 200 patients (35%) were diagnosed as stage T4. Only positive lymph node status and grade 3 were reported as risk factors for distant metastases in patients with stage T3 and T4 cancer. Conclusion There are differences in the clinicopathological features among breast cancer patients with primary metastases and those without. Receptor expression and histological type play a minor role in the risk for metastasis in patients with stage T3 and T4 disease when compared to patients with T1 pmBC tumours. On initial diagnosis, lobular histology and Luminal B positivity (Her 2 positive) in T1 pmBC were determined to be risk factors for primary metastatic disease.
Block copolymer self-assembly in solution paves the way for the construction of well-defined compartmentalized nanostructures. These are excellent templates for the incorporation and stabilisation of ...nanoparticles (NPs), giving rise to highly relevant applications in the field of catalysis or sensing. However, the regio-selective incorporation of NPs in specific compartments is still an issue, especially concerning the loading with different NP types. Using crystallisation-driven self-assembly (CDSA), functional worm-like crystalline-core micelles (wCCMs) with a tailor-made, nanometre-sized patchy corona were prepared as versatile templates for the incorporation and stabilisation of metal and metal oxide NPs. Different strategies, like ligand exchange or co-precipitation of polymer stabilised NPs with one surface patch, were developed that allow the incorporation of NPs in specific regions of the patchy wCCM corona. Independent of the NP type and the incorporation method, the NPs showed no tendency for agglomeration and were fixed within the corona patches of the wCCMs. The binary loading of patchy micelles with metal and metal oxide NPs was realised by combining different loading strategies, yielding hybrids with homogeneously dispersed NPs guided by the patchy structure of the template.
Patchy micelles are efficient templates for the regio-selective incorporation of nanoparticles, allowing the construction of tailor-made binary hybrids.
Abstract Many factors shape public perceptions of extreme weather risk; understanding these factors is important to encourage preparedness. This article describes a novel workshop designed to ...encourage individual and community decision-making about predicted storm surge flooding. Over 160 U.S. college students participated in this 4-h experience. Distinctive features included 1) two kinds of visualizations, standard weather forecasting graphics versus 3D computer graphics visualization; 2) narrative about a fictitious storm, role-play, and guided discussion of participants’ concerns; and 3) use of an “ethical matrix,” a collective decision-making tool that elicits diverse perspectives based on the lived experiences of diverse stakeholders. Participants experienced a narrative about a hurricane with potential for devastating storm surge flooding on a fictitious coastal college campus. They answered survey questions before, at key points during, and after the narrative, interspersed with forecasts leading to predicted storm landfall. During facilitated breakout groups, participants role-played characters and filled out an ethical matrix. Discussing the matrix encouraged consideration of circumstances impacting evacuation decisions. Participants’ comments suggest several components may have influenced perceptions of personal risk, risks to others, the importance of monitoring weather, and preparing for emergencies. Surprisingly, no differences between the standard forecast graphics versus the immersive, hyperlocal visualizations were detected. Overall, participants’ comments indicate the workshop increased appreciation of others’ evacuation and preparation challenges.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract Background Surgery is the mainstay of treatment for early ovarian cancer both as therapeutic and comprehensive staging. Only the latter allows appropriate tailoring of systemic treatment. ...However, the compliance with guidelines for comprehensive staging has been reported to be only moderate and, therefore, re-staging procedures are commonly indicated to avoid undertreatment. The purpose of our study was to evaluate re-operation in a tertiary gynecologic oncology unit after primary operation for presumably ovarian cancer FIGO I-IIIA in general gynecology departments. Material and methods Forty consecutive patients after primary surgery in the outside institutions for presumed early ovarian cancer with assumed tumor spread limited to the pelvis (FIGO I-IIIA) admitted to our department between 1999 and 2007 were included. In 35 cases re-staging surgery in our unit was indicated. The intra- and post-operative results were compared with initial diagnosis and sites of undetected disease were evaluated. Reasons for re-staging and referral pattern were studied. Results 40 patients were enrolled of whom 53% came by self-referral. Only 18% were referred by the primary surgeon and the remaining patients were referred by their home gynecologist. Only 5 patients (13%) were classified as having had a comprehensive staging by surgical records and pathology reports and 35 patients underwent comprehensive re-staging laparotomy after which 20 patients (50%) experienced an upstaging including 13 patients with final diagnosis of FIGO stage IIIC. Most frequent sites of primarily undetected tumor were peritoneum (pelvic 34%, diaphragm 13%, paracolic 8%), lymph nodes (para aortic 32%, pelvic 11%), intestines 24%, and residual omental tissue 18%. The indication for post-operative chemotherapy was modified in 53% of patients. Conclusion Comprehensive staging of presumed early ovarian cancer has been described as major problem especially outside gynecologic oncology units. Re-staging results in our department confirmed this deficiency by showing a considerable proportion of upstaging associated with alterations of recommendations for systemic treatment. However, series like this may even underestimate the problem, because incomplete staging is unfortunately accompanied by non-systematic referral practices not reflecting staging quality.
Cloning and sequencing of a 7.1 kb DNA fragment from Agrobacterium sp IP I-671 revealed seven open reading frames (ORFs) encoding D-hydantoinase, D-carbamoylase and putative hydantoin racemase, ...D-amino acid oxidase and NAD(P)H-flavin oxidoreductase. Two incomplete ORFs flanking the hydantoin utilization genes showed similarities to genes involved in transposition. Expression of the D-hydantoinase and D-carbamoylase gene in Escherichia coli gave mainly inactive protein concentrated in inclusion bodies, whereas homologous expression on an RSF1010 derivative increased hydantoinase and D-carbamoylase activity 2.5-fold and 10-fold, respectively, in this strain. Inactivation of the D-carbamoylase gene in Agrobacterium sp IP I-671 led to a complete loss of detectable carbamoylase activity whereas the low hydantoinase activity remaining after inactivation of the D-hydantoinase gene indicated the presence of a second hydantoinase-encoding gene. Two plasmids of 80 kb and 190 kb in size were identified by pulsed-field gel electrophoresis and the cloned hydantoin utilization genes were found to be localized on the 190 kb plasmid.
Clinicians demand for methods to monitor effects of direct anticoagulants in the emergency setting. We recently described a coagulation assay based on surface acoustic waves (SAW) technology, which ...quantifies anticoagulant effects by image processing. Here we describe the first step in miniaturizing this laboratory method and provide a portable prototype that contains the optical illumination and automatic on-board image processing.
A device about the size of a shoebox was realized that contains the SAW-chip, the signal generator, the LED illumination, as well as the necessary lenses, aperture, and CCD sensor. The microspheres in the blood were mixed by SAW, and the movement of the microspheres was quantified by on-board image processing. Upon contact with activation induced coagulation, this movement ceases, and coagulation times were measured and compared to the manual methods obtained by standard fluorescent microscopy. A major advantage of our method is the low amount of blood (~ 6 μL) necessary for testing.
Results from the prototype correlated accurately with manual methods (Pearson correlation coefficient r = 0.9644). SAW-induced clotting time under anticoagulant treatment with dabigatran or rivaroxaban was well correlated with physicochemically determined plasma concentrations of these DOACs in anticoagulated patients. Compared to manual alignment of the chip under the fluorescence microscope, the prototype had a lower coefficient of variation.
The last evolution step towards a point-of-care (POC)-device would be the development of a cartridge (containing calcium chloride and fluorescent label) such that a drop of blood can be introduced into the reaction vessel by a fluid actuator system.
Experimental and theoretical results for the rapid expansion of supercritical solutions (RESS-process) are presented. Experiments were carried out with the solvents carbon dioxide (CO
2) and ...trifluoromethane (CHF
3) and the organic solutes cholesterol, benzoic acid and griseofulvin. It is shown that for each of these solutes it is possible to produce particles in the size range of
200
nm
which leads to improved dissolution. Furthermore, to demonstrate the higher bioavailability of the micronized pharmaceutical griseofulvin as of the original material, results of a dissolution experiment are shown. Besides the experiments the flow and particle formation and growth in the expansion unit (inlet–capillary nozzle–supersonic free jet) of the RESS-process is modelled numerically. The model to calculate the flow field consists of mass, momentum and energy balances as well as the extended generalized Bender equation of state (egB-EoS). The flow is assumed to be steady, one-dimensional, viscid and non-adiabatic. The general dynamic equation (GDE) is included to model the particulate phase. The results of the modelling show that particle formation occurs in most of the cases mainly in the supersonic free jet and that the main mechanism for particle growth is coagulation. Furthermore, it can be inferred from the high particle number concentration at the Mach disk that particle growth by coagulation continues in the subsonic part of the free jet (expansion chamber). Experimental results with variation of additional air supply to the expansion chamber are presented to confirm the theoretical results.
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