80 research outputs found
Diluted antiferromagnets in a field seem to be in a different universality class than the random-field Ising model
We perform large-scale Monte Carlo simulations using the Machta-Newman-Chayes
algorithms to study the critical behavior of both the diluted antiferromagnet
in a field with 30% dilution and the random-field Ising model with Gaussian
random fields for different field strengths. Analytical calculations by Cardy
[Phys. Rev. B 29, 505 (1984)] predict that both models map onto each other and
share the same universality class in the limit of vanishing fields. However, a
detailed finite-size scaling analysis of both the Binder cumulant and the
two-point finite-size correlation length suggests that even in the limit of
small fields, where the mapping is expected to work, both models are not in the
same universality class. Therefore, care should be taken when interpreting
(experimental) data for diluted antiferromagnets in a field using the
random-field Ising model. Based on our numerical data, we present analytical
expressions for the phase boundaries of both models.Comment: 12 pages, 9 figures, 5 table
Ferkelverluste verringern: Auswirkungen einer verlÀngerten SÀugezeit auf die Konstitution der Aufzuchtferkel
Auf Grund der Vorgaben der EU-Ăko-Verordnung werden Ferkel in der ökologischen Ferkelerzeugung in der Regel mit 6 Wochen abgesetzt. Dies geht in vielen FĂ€llen mit einem verminderten Gesundheits- und Leistungsstatus einher, da sich zu diesem Zeitpunkt Ferkel in einer Ă€uĂerst sensiblen physiologischen Phase befinden. Im vorliegenden Versuch sollte ĂŒberprĂŒft werden, ob die durch einen spĂ€teren Absetzzeitpunkt Ă€lteren Ferkel den Belastungen rund um das Absetzen besser gewachsen sind, und sich durch bessere produktionstechnisch-biologische Leistungen (Modul 1) sowie einen besseren Immunstatus (Modul 2) auszeichnen. Dazu wurden auf dem Versuchsbetrieb Wulmenau des Instituts fĂŒr ökologischen Landbau 36 Sauen auf 2 Verfahren (Kontrolle: 42 Tage SĂ€ugezeit; Versuch: 63 Tage SĂ€ugezeit) mit je 18 Tieren aufgeteilt. Der dritte und letzte Durchgang endete im Sommer 2007. Im Modul 1 wurden insgesamt 3 Wurfnummern mit 108 WĂŒrfen von 36 Sauen mit zusammen mehr als 1400 Ferkeln ausgewertet. Es zeigte sich, dass die lĂ€nger gesĂ€ugten Ferkel signifikant bessere produktionstechnische Leistungsdaten und signifikant verringerte Behandlungsinzidenzen aufwiesen, die Abgangsraten sich aber nicht statistisch gesichert unterschieden. Auf die Kondition der Sauen und den Zustand der GesĂ€ugeleiste hatte die verlĂ€ngerte SĂ€ugezeit keinerlei negative Auswirkungen. Das Modul 2 umfasste die Wurfnum-mern 2 und 3 mit 72 WĂŒrfen von 36 Sauen mit einer Stichprobe von 576 Ferkeln (8 Ferkel/Wurf). Es wurden die Ferkel zu unterschiedlichen Zeitpunkten mit einem ihnen âbekanntenâ Antigen (durch Muttertier-Vakzinierung und passiven Transfer ĂŒber die Sauenmilch) und mit einem ihnen âunbekanntenâ Antigen vakziniert. Im Plasma wurden mittels ELISA die Konzentration von Immunglobulin G (IgG) sowie die antigenspezifischen IgG-Antikörper gemessen. Die Untersuchungen des Moduls 2 ergaben keinen besseren Immunstatus fĂŒr die spĂ€ter abgesetzten Ferkel. Trotzdem erscheint eine VerlĂ€ngerung der SĂ€ugezeit ĂŒber die Mindestvorgabe von 40 Tagen hinaus empfehlenswert
Ăber eine Nebenreaktion bei der Reduktion [alpha], [beta]-ungesĂ€ttigter Ester mit Lithiumalanat
The reaction of [alpha], [beta]-unsaturated esters gives the normal alcohols and dimeric compounds. The structures are investigated in the case of methyl crotonate and methyl y-trimethyl crotonate
Rotationplasty in the Elderly
Purpose. Rotationplasty has proven its efficacy in the treatment of malignant bone tumors of the lower extremity in predominantly young patients. To our knowledge this procedure has not been reported in patients over 60 years before. Materials and Methods. 3 patients over 60 years with an A1-rotationplasty because of a sarcoma were included in this study. Complications and functional results were recorded. In one patient an electromyography was done. Results. Despite electromyography showing good adaptation of the muscles to the altered function, the functional results of these three patients were limited. two out of three patients needed a cane for walking distances over 200 meters. No secondary amputation was necessary. Discussion. Our study demonstrates that rotationplasty is an alternative to an above-knee amputation in older patients but with poorer functional results in comparison to younger patients. However, limb-salvage surgery should be preferred whenever possible
The Influence of Elementary Silver Versus Titanium on Osteoblasts Behaviour In Vitro Using Human Osteosarcoma Cell Lines
Purpose. The antimicrobial effect of a silver-coated tumor endoprosthesis has been proven in clinical and experimental trials. However, in the literature there are no reports concerning the effect of elementary silver on osteoblast behaviour. Therefore, the prosthetic stem was not silver-coated because of concerns regarding a possible inhibition of the osseointegration. The aim of the present study was to investigate the effect of 5â25 mg of elementary silver in comparison to Ti-6Al-4V on human osteosarcoma cell lines (HOS-58, SAOS).
Methods. Cell viability was determined by measuring the MTT proliferation rate. Cell function was studied by measuring alkaline phosphatase (AP) activity and osteocalcine production. Results. In the HOS-58 cells, the AP activity was statistically significant (P < 0.05) higher at a supplement of 5â10 mg of silver than of Ti-6 Al-4V at the same doses. For both cell lines, a supplement above 10 mg of silver resulted in a reduced AP activity in comparision to the Ti-6 Al-4V group, but a statistically significant difference (P < 0.05) was observed at a dose of 25 mg for the SAOS cells only. At doses of 20â25 mg in the HOS-58 cells and 10â25 mg in the SAOS cells, the reduction of the proliferation rate by silver was statistically significant (P < 0.05) compared to the Ti-6 Al-4V supplement. Discussion. In conclusion, elementary silver exhibits no cytotoxicity at low concentrations. In contrast, it seems to be superior to Ti-6 Al-4V concerning the stimulation of osteogenic maturation at these concentrations, whereas at higher doses it causes the known cytotoxic properties
Giant Cell Tumors of the Axial Skeleton
Background. We report on 19 cases of giant cell tumor of bone (GCT) affecting the spine or sacrum and evaluate the outcome of different treatment modalities. Methods. Nineteen patients with GCT of the spine (n = 6) or sacrum (n = 13) have been included in this study. The mean followup was 51.6 months. Ten sacral GCT were treated by intralesional procedures of which 4 also received embolization, and 3 with irradiation only. All spinal GCT were surgically treated. Results. Two (15.4%) patients with sacral and 4 (66.7%) with spinal tumors had a local recurrence, two of the letter developed pulmonary metastases. One local recurrence of the spine was successfully treated by serial arterial embolization, a procedure previously described only for sacral tumors. At last followup, 9 patients had no evidence of disease, 8 had stable disease, 1 had progressive disease, 1 died due to disease. Six patients had neurological deficits. Conclusions. GCT of the axial skeleton have a high local recurrence rate. Neurological deficits are common. En-bloc spondylectomy combined with embolization is the treatment of choice. In case of inoperability, serial arterial embolization seems to be an alternative not only for sacral but also for spinal tumors
Evaluation of the biomarker candidate MFAP4 for non-invasive assessment of hepatic fibrosis in hepatitis C patients
The human microfibrillar-associated protein 4 (MFAP4) is located to extracellular matrix fibers and plays a role in disease-related tissue remodeling. Previously, we identified MFAP4 as a serum biomarker candidate for hepatic fibrosis and cirrhosis in hepatitis C patients. The aim of the present study was to elucidate the potential of MFAP4 as biomarker for hepatic fibrosis with a focus on the differentiation of no to moderate (F0âF2) and severe fibrosis stages and cirrhosis (F3 and F4, Desmet-Scheuer scoring system).
MFAP4 levels were measured using an AlphaLISA immunoassay in a retrospective study including = 542 hepatitis C patients. We applied a univariate logistic regression model based on MFAP4 serum levels and furthermore derived a multivariate model including also age and gender. Youden-optimal cutoffs for binary classification were determined for both models without restrictions and considering a lower limit of 80% sensitivity (correct classification of F3 and F4), respectively. To assess the generalization error, leave-one-out cross validation (LOOCV ) was performed.
MFAP4 levels were shown to differ between no to moderate fibrosis stages F0âF2 and severe stages (F3 and F4) with high statistical significance ( test on log scale, value ). In the LOOCV, the univariate classification resulted in 85.8% sensitivity and 54.9% specificity while the multivariate model yielded 81.3% sensitivity and 61.5% specificity (restricted approaches).
We confirmed the applicability of MFAP4 as a novel serum biomarker for assessment of hepatic fibrosis and identification of high-risk patients with severe fibrosis stages in hepatitis C. The combination of MFAP4 with existing tests might lead to a more accurate non-invasive diagnosis of hepatic fibrosis and allow a cost-effective disease management in the era of new direct acting antivirals
Evaluation of the biomarker candidate MFAP4 for non-invasive assessment of hepatic fibrosis in hepatitis C patients
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