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31.
32.
The present communication broadens the data base for determinations of the non-reference condition correction factor kNR needed in high-energy photon dosimetry to accomplish the use of various detectors under non-reference conditions. Following our previous strategy of calculating semiempirical values of kNR and correlating them with the mean photon energy Em at the point of measurement in a large water phantom, the values of Em are now stated for 6 and 15 MV photon radiations of accelerators with and without flattening filters, square field sizes from 1 to 30 cm side length and depths from 0 to 28 cm. The unambiguity of the kNR-Em correlation is again confirmed and is quantified by fitting formulae for air-filled ionization chambers, TLD detectors and Si diodes. This survey provides a practicable access to the kNR values, particularly for the non-water equivalent detectors to be used in small-field dosimetry 相似文献
33.
Michael C. Seidenbusch Dietrich Harder Dieter F. Regulla Karl Schneider 《Zeitschrift für medizinische Physik》2014,24(2):123-137
Estimations of organ doses DT received during computed tomographic examinations are usually performed by applying conversion factors to basic dose indicators like the computed tomography dose index (CTDI) or the dose-length-product (DLP). In addition to the existing conversion factors for beam apertures of 5 mm or 10 mm, we present new DLP-DT conversion factors adapted to high-resolution CT (HRCT) examinations of infants and young children with beam apertures of the order of 1 mm and under consideration of bow tie filtration. Calculations are performed on mathematical MIRD phantoms for an age range from 0, 1, 5, 10, 15 up to (for comparison) 30 years by adapting PCXMC, a Monte Carlo algorithm originally developed by STUK (Helsinki, Finland) for dose reconstructions in projection radiography. For this purpose, each single slice CT examination is approximated by a series of corresponding virtual planar radiographies comprising all focus positions. The transformation of CT exposure parameters into exposure parameters of the series of corresponding planar radiographies is performed by a specially developed algorithm called XCT. The DLP values are evaluated using the EGSRay code. The new method is verified at a beam aperture of 10 mm by comparison with formerly published conversion factors. We show that the higher spatial resolution leads to an enhanced DLP-DT conversion factor if a small organ (e. g. thyroid gland, mammae, uterus, ovaries, testes) is exactly met by the chosen CT slice, while the conversion factor is drastically reduced if the chosen CT slice is positioned above or below the organ. This effect is utilized for dose-saving examinations with only a few single slices instead a full scan, which technique is applied in about 10% of all paediatric chest CT examinations. 相似文献
34.
35.
Sidsel Kirstine Harder 《Substance use & misuse》2015,50(6):759-767
With a starting point in women's studies, this article moves on to approach the nightclub as a place of embodiment for both genders by introducing neo-Lacanian insights combined with Baudrillardian concepts. We look at three young drug-experienced men interviewed for a Danish club study (2008–09). The article examines how the risks of losing masculinity, losing sexual opportunities, and losing friends are managed in nightlife. Since masculinity becomes invested in the fantasy of the drug and the utopian party, these young men can be perceived as risking their male position when the party does not work out as planned. 相似文献
36.
Timm Harder Sebastian Maurer-Stroh Anne Pohlmann Elke Starick Detlef H?reth-B?ntgen Karin Albrecht Gunter Pannwitz Jens Teifke Vithiagaran Gunalan Raphael T.C. Lee Carola Sauter-Louis Timo Homeier Christoph Staubach Carola Wolf Günter Strebelow Dirk H?per Christian Grund Franz J. Conraths Thomas C. Mettenleiter Martin Beer 《Emerging infectious diseases》2015,21(5):860-863
Highly pathogenic avian influenza (H5N8) virus, like the recently described H5N8 strain from Korea, was detected in November 2014 in farmed turkeys and in a healthy common teal (Anas crecca) in northeastern Germany. Infected wild birds possibly introduced this virus. 相似文献
37.
Although the administration of recombinant coagulation factor VIIa (rFVIIa) is a well established treatment in haemophilia with inhibitory antibodies, monitoring the therapeutic efficacy is still a problem. This is because the complete haemostatic effect in vivo depends on negatively charged surfaces provided by exposed lipids from activated platelets which are not present in standard clinical assays using plasma. The thrombin generation assay, however, measures the endogenous thrombin potential (ETP) in platelet-rich plasma (PRP) and this assay might be useful for monitoring the haemostatic response to rFVIIa. We characterized the in vitro concentration-response relationship of rFVIIa and the thrombin generation parameters ETP, PEAK and TIME TO PEAK using platelet-rich plasma (PRP) and rFVIIa at concentrations between one and five times the therapeutic dose. We also studied the effect of inhibiting tissue-factor and the intrinsic coagulation pathway using excess TF-neutralizing antibodies and corn trypsin inhibitor (CTI), respectively. There was a sigmoid relationship between ETP and PEAK and the dose of rFVIIa. Increasing rFVIIa concentrations between 100 and 500 U/ml resulted in a progressive increase in ETP, whereas supratherapeutical concentrations led to a plateau phase. The plateau phase differed between patients, suggesting a biological variation in the maximum ETP. Neutralization of plasma TF with TF-Ab partially decreased FVIIa efficacy. The inhibitory effect of CTI on rFVIIa-induced thrombin generation via the intrinsic pathway was negligible. The thrombin generation assay using PRP is a useful test for determining the sufficient efficacy of rFVIIa in blood. Once a plateau level is reached, higher doses of rFVIIa have no additional effect on haemostatic efficacy. The variation in plateau levels between subjects indicates that there are inter-individual differences in the level of thrombin activity that can be generated. High doses of rFVIIa are effective even in the absence of TF. 相似文献
38.
Epoxyeicosatrienoic acids (EETs) are lipid metabolites that are synthesized in vascular endothelial cells. They are released by stimulation of their muscarinic receptors, and induce vaso-relaxation of cerebral blood vessels. In addition, cytochrome P450 epoxygenase enzymes, which catalyze the formation of epoxyeicosatrienoic acids, especially after stimulation by the excitatory neurotransmitter glutamate, are present in astrocytes, an abundant cell type in the brain that extends foot processes onto the cerebral microvessels. Using a modification of an efficient, recently developed, fluorescent assay, we have detected the presence of EETs in endothelial cells cultured from the cortex of rat brains as well as in neonatal astrocytes. We propose that both these cell types provide a dual supply of EETs to increase cerebral blood flow in order to meet systemic as well as localized nutrient demands of cells in the brain. 相似文献
39.
Hernando-Harder AC von Bünau R Nadarajah M Singer MV Harder H 《Digestive diseases and sciences》2008,53(2):443-450
E. coli strain Nissle 1917 (EcN) is a probiotic clinically used with various indications. However, especially at the beginning of
treatment, some patients report abdominal bloating. In a prospective, randomized, double-blind study in 30 healthy individuals
we assessed the influences of EcN on intestinal gas dynamics and abdominal sensation. After one week without medication volunteers
orally received 2.5–25 × 109 colony-forming units of EcN or placebo per day for 21 days. EcN was well tolerated and did not significantly affect abdominal
symptoms, stool frequency or stool consistency. During gas challenge at different days no difference in the perception scores
(range from 0 = no perception to 6 = pain) was observed between the two groups: the mean perception score was 1.2 (SD 0.2)
in the EcN group and 1.4 (SD 0.2) in the placebo group. EcN had no relevant influence on intestinal gas dynamics. 相似文献
40.
B. Speck A. Tichelli E. Widmer F. Harder M. Kissling A. Würsch Ch Stebler Gysi E. Signer M. Bargetzi B. Orth A. Gratwohl C. Nissen 《British journal of haematology》1996,92(4):818-824
The role of splenectomy in aplastic anaemia (AA) is controversial. The hazards of operating on a severely pancytopenic patient, the fear of compromising the patient’s immune function, and the improvement of non-surgical treatment have made splenectomy unpopular in this disease. We have evaluated positive and adverse effects of splenectomy in 80 patients with severe aplastic anaemia (SAA) treated with antilymphocyte globulin (ALG) (group A), using 52 nonsplenectomized ALG patients as controls (group B). All patients survived the operation. Nonfatal complications of surgery occurred in 10 (12.5%). Splenectomy induced a significant increase of peripheral blood neutrophils, reticulocytes and platelets within 2 weeks, followed by a continuous increase of all values over the following weeks. 28/132 patients (21%) developed a late clonal disorder of haemopoiesis, paroxysmal nocturnal haemoglobinuria (PNH) or myelodysplastic syndrome (MDS), or both. Their incidence was identical in groups A and B. 13/28 (59%) died, 10/17 (59%) in group A and 3/11 (27%) in group B (not significant (n.s.)). Overall probability of survival at 18 years after ALG was 51 ± 6% for group A and 61 ± 7% for group B (n.s.). We conclude that splenectomy in AA is safe. It induces an immediate increase of peripheral blood counts and, thereafter, a continuous improvement of haemopoiesis. It does not increase the incidence of late clonal complications but has a borderline effect on mortality from these disorders. Splenectomy should be reconsidered in selective nontransplanted patients who have prolonged transfusion requirements despite otherwise optimal treatment. 相似文献