Showing papers by "University of Erlangen-Nuremberg published in 2003"

Sharper Focus for a Radially Polarized Light Beam

Abstract: We experimentally demonstrate for the first time that a radially polarized field can be focused to a spot size significantly smaller [$0.16(1){\ensuremath{\lambda}}^{2}$] than for linear polarization ($0.26{\ensuremath{\lambda}}^{2}$). The effect of the vector properties of light is shown by a comparison of the focal intensity distribution for radially and azimuthally polarized input fields. For strong focusing, a radially polarized field leads to a longitudinal electric field component at the focus which is sharp and centered at the optical axis. The relative contribution of this component is enhanced by using an annular aperture.

Self-consistent mean-field models for nuclear structure

Abstract: The authors review the present status of self-consistent mean-field (SCMF) models for describing nuclear structure and low-energy dynamics. These models are presented as effective energy-density functionals. The three most widely used variants of SCMF's based on a Skyrme energy functional, a Gogny force, and a relativistic mean-field Lagrangian are considered side by side. The crucial role of the treatment of pairing correlations is pointed out in each case. The authors discuss other related nuclear structure models and present several extensions beyond the mean-field model which are currently used. Phenomenological adjustment of the model parameters is discussed in detail. The performance quality of the SCMF model is demonstrated for a broad range of typical applications.

Somatic mutations in PTPN11 in juvenile myelomonocytic leukemia, myelodysplastic syndromes and acute myeloid leukemia

Abstract: We report here that individuals with Noonan syndrome and juvenile myelomonocytic leukemia (JMML) have germline mutations in PTPN11 and that somatic mutations in PTPN11 account for 34% of non-syndromic JMML. Furthermore, we found mutations in PTPN11 in a small percentage of individuals with myelodysplastic syndrome (MDS) and de novo acute myeloid leukemia (AML). Functional analyses documented that the two most common mutations in PTPN11 associated with JMML caused a gain of function.

Detection of Coronary Artery Stenoses With Thin-Slice Multi-Detector Row Spiral Computed Tomography and Multiplanar Reconstruction

Abstract: Background— We analyzed the accuracy of multi-detector row spiral computed tomography (MDCT) using a 16-slice CT scanner with improved spatial and temporal resolution, as well as routine premedication with β-blockers for detection of coronary stenoses. Methods and Results— Seventy-seven patients with suspected coronary disease were studied by MDCT (12×0.75-mm cross-sections, 420 ms rotation, 100 mL contrast agent IV at 5 mL/s). Patients with a heart rate above 60/min received 50 mg atenolol before the scan. In axial MDCT images and multiplanar reconstructions, all coronary arteries and side branches with a diameter of 1.5 mm or more were assessed for the presence of stenoses exceeding 50% diameter reduction. In comparison to invasive coronary angiography, MDCT correctly classified 35 of 41 patients (85%) as having at least 1 coronary stenosis and correctly detected 57 of 78 coronary lesions (73%). After excluding 38 of 308 coronary arteries (left main, left anterior descending, left circumflex, and right ...

Proteinase-Activated Receptor-2 Mediates Itch: A Novel Pathway for Pruritus in Human Skin

Abstract: We examined whether neuronal proteinase-activated receptor-2 (PAR-2) may be involved in pruritus of human skin. The endogenous PAR-2 agonist tryptase was increased up to fourfold in atopic dermatitis (AD) patients. PAR-2 was markedly enhanced on primary afferent nerve fibers in skin biopsies of AD patients. Intracutaneous injection of endogenous PAR-2 agonists provoked enhanced and prolonged itch when applied intralesionally. Moreover, itch upon mast cell degranulation was abolished by local antihistamines in controls but prevailed in AD patients. Thus, we identified enhanced PAR-2 signaling as a new link between inflammatory and sensory phenomena in AD patients. PAR-2 therefore represents a promising therapeutic target for the treatment of cutaneous neurogenic inflammation and pruritus.

Patterns of cortical reorganization in complex regional pain syndrome

Abstract: Objective To use magnetoencephalography to assess possible cortical reorganization in the primary somatosensory cortex (S1) of patients with complex regional pain syndrome (CRPS). Background Patterns of pain and sensory symptoms in CRPS may indicate plastic changes of the CNS. Methods Magnetic source imaging was used to explore changes in the cortical representation of digits (D) 1 and 5 in relation to the lower lip on the unaffected and affected CRPS side in 12 patients. Results The authors found a significant shrinkage of the extension of the cortical hand representation for the CRPS affected side. The center of the hand was shifted toward the cortical representation of the lip. The cortical reorganization correlated with the amount of CRPS pain (r = 0.792), as measured by the McGill questionnaire, and the extent of mechanical hyperalgesia (r = 0.860). Using multiple regression analysis, the best predictor for the plastic changes was found to be mechanical hyperalgesia. Additionally, S1 sources following tactile stimulation were significantly increased on the CRPS side compared to the unaffected limb. Conclusions This study showed reorganization of the S1 cortex contralateral to the CRPS affected side. The reorganization appeared to be linked to complaints of neuropathic pain.

Functionalization of single-walled carbon nanotubes with (R-)oxycarbonyl nitrenes.

Abstract: Sidewall functionalization of single-walled carbon nanotubes (SWCNTs) via the addition of (R-)oxycarbonyl nitrenes allows for the covalent binding of a variety of different groups such as alkyl chains, aromatic groups, dendrimers, crown ethers, and oligoethylene glycol units. Such additions lead to a considerable increase in the solubility in organic solvents such as 1,1,2,2-tetrachloroethane (TCE), dimethyl sulfoxide (DMSO), and 1,2-dichlorobenzene (ODCB). The highest solubilities of 1.2 mg/mL were found for SWCNT adducts with nitrenes containing crown ether of oligoethylene glycol moieties in DMSO and TCE, respectively. The presence of chelating donor groups within the addends allowed for the complexation of Cu2+ and Cd2+. Atomic force microscopy (AFM) and transmission electron microscopy (TEM) revealed that the functionalized tubes form thin bundles with typical diameters of 10 nm. The presence of thin bundles in solution is supported by 1H NMR spectroscopy. The elemental composition of the functionali...

Self-Organized Porous Titanium Oxide Prepared in H 2 SO 4 / HF Electrolytes

Abstract: The formation of porous on titanium was investigated in electrolytes containing low concentrations of HF (0.05-0.4 wt %). Under optimized electrolyte conditions and extended polarization, highly ordered porous is obtained that consists of pore arrays with single pore diameter of 140 nm and a pore spacing of 150 nm. During the formation process, significant current oscillations are observed with an amplitude which depends strongly on the HF content of the electrolyte. Electrochemical, scanning electron microscope and X-ray photoelectron spectroscopy investigations show that the porous layer forms under a competition of formation and oxide dissolution up to a limiting thickness of and that the time scale for complete self-ordering for the investigated systems is in the order of several hours. © 2003 The Electrochemical Society. All rights reserved.

Functionally graded materials for biomedical applications

Abstract: Functional gradation is one characteristic feature of living tissue. Bio-inspired materials open new approaches for manufacturing implants for bone replacement. Different routes for new implant materials are presented using the principle of functional gradation. An artificial biomaterial for knee joint replacement has been developed by building a graded structure consisting of ultra-high molecular weight polyethylene (UHMWPE) fibre reinforced high-density polyethylene combined with a surface of UHMWPE. The ingrowth behaviour of titanium implants into hard tissue can be improved by depositing a graded biopolymer coating of fibronectin, collagen types I and III with a gradation, derived from the mechanisms occurring during healing in vivo. Functionally graded porous hydroxyapatite (HAP) ceramics can be produced using alternative routes, e.g. sintering of laminated structures of HAP tapes filled with polymer spheres or combining biodegradable polyesters such as polylactide, polylactide-co-glycolide and polyglycolide, with carbonated nanocrystalline hydroxyapatite. HAP–collagen I scaffolds are an appropriate material for in vitro growth of bone. The scaffold has to be functionally graded in order to create an optimised mechanical behaviour as well as the intended improvement of the cell ingrowth.

The dynamics of masculine-agentic and feminine-communal traits: findings from a prospective study.

Abstract: A reciprocal impact hypothesis posits an influence of gender-related traits (agency and communion) on role enactment and a reciprocal impact of role enactment on gender-related traits, for both men and women Specifically, in this study it was predicted that agency influences career success and career success influences agency In addition, the reciprocal influence of communion and family roles was examined A prospective study with almost 2,000 university graduates, who were tested after graduation and 15 years later, clearly supported the reciprocal impact hypothesis for agency and career success Communion influenced family roles, but there was no reciprocal influence Implications for theories of career success and of sex and gender are discussed

Number Theoretic Background

Abstract: This paper is an expanded version of some of the lectures given at the summer school in Bologna. In these lectures we gave an introduction to very basic number theory, assuming practically no background. The lectures were intended for graduate students in Math and Physics and while the material is completely standard, we tried to make the presentation as elementary as possible.

Short-term infusion of the μ-opioid agonist remifentanil in humans causes hyperalgesia during withdrawal

Abstract: Numerous animal studies suggest that acute and chronic exposure to opioids can be associated with the development of hyperalgesia, i.e. an increased sensitivity to noxious stimuli. Hyperalgesia has been documented during withdrawal and on occasion while animals were still exposed to opioids. A pivotal role in the genesis of opioid-associated hyperalgesia has been attributed to a pain facilitating system involving the N-methyl-D-aspartate (NMDA)-receptor. In humans little direct evidence documents opioid-associated hyperalgesia, albeit observational data suggest that such hyperalgesia may be relevant in a clinical context. This study used a double blind, randomized, crossover and placebo-controlled design to test in opioid-naive, healthy human volunteers whether hyperalgesia would develop within 30 min of stopping a 90-min infusion with the mu-opioid agonist remifentanil, and whether co-administration of the NMDA-receptor antagonist S-ketamine would prevent such hyperalgesia. We found that a skin area with pre-existing mechanical hyperalgesia was significantly enlarged after stopping the remifentanil infusion. However, the pain response to heat assessed in regular skin was not different before and after the infusion of remifentanil. Co-administration of the NMDA-receptor antagonist S-ketamine abolished observed enlargement of the hyperalgesic skin area. This study provides direct evidence in humans that short-term administration of an opioid can enhance hyperalgesia as observed during withdrawal and points to a potential role of the NMDA-receptor system in mediating such a hyperalgesic response. This study also points to a differential susceptibility of different pain modalities for the expression of hyperalgesia associated with opioid administration.

Strain-Rate Imaging During Dobutamine Stress Echocardiography Provides Objective Evidence of Inducible Ischemia

Abstract: Background— Interpretation of dobutamine stress echocardiography (DSE) is subjective and strongly dependent on the skills of the reader. Strain-rate imaging (SRI) by tissue Doppler may objectively ...

Chemical response pattern of different classes of C-nociceptors to pruritogens and algogens.

Abstract: Vasoneuroactive substances were applied through intradermal microdialysis membranes and characterized as itch- or pain-inducing in psychophysical experiments. Histamine always provoked itching and rarely pain, capsaicin always pain but never itching. Prostaglandin E2 (PGE2) led preferentially to moderate itching. Serotonin, acetylcholine, and bradykinin induced pain more often than itching. Subsequently the same substances were used in microneurography experiments to characterize the sensitivity profile of human cutaneous C-nociceptors. The responses of 89 mechanoresponsive (CMH, polymodal nociceptors), 52 mechanoinsensitive, histamine-negative (CMiHis−), and 24 mechanoinsensitive, histamine-positive (CMiHis+) units were compared. CMiHis+ units were most responsive to histamine and to PGE2 and less to serotonin, ACh, bradykinin, and capsaicin. CMH units (polymodal nociceptors) and CMiHis−units showed significantly weaker responses to histamine, PGE2, and acetylcholine. Capsaicin and bradykinin responses w...

Central role for type I interferons and Tyk2 in lipopolysaccharide-induced endotoxin shock.

Abstract: Toll-like receptor-4 activation by lipopolysaccharide (LPS) induces the expression of interferon-beta (IFN-beta) in a MyD88-independent manner. Here we report that mice devoid of the JAK protein tyrosine kinase family member, Tyk2, were resistant to shock induced by high doses of LPS. Basal and LPS-induced expression of IFN-beta and IFN-alpha4 mRNA in Tyk2-null macrophages were diminished. However, Tyk2-null mice showed normal systemic production of nitric oxide and proinflammatory cytokines and the in vivo response to tumor necrosis factor (TNF) was unperturbed. IFN-beta-null but not STAT1-null mice were also resistant to high dose LPS treatment. Together, these data suggest that Tyk2 and IFN-beta are essential effectors in LPS induced lethality.

Quantitative assessment of gustatory function in a clinical context using impregnated "taste strips".

Abstract: Assessment of gustatory sensitivity in a clinical setting is the prerequisite for correct diagnosis and adequate treatment of taste dysfunction. Despite of this, no taste test has been established for the routine clinical testing. The aim of the present study was to create a protocol which is easy to administer. The presently used technique is based on strips made from filter paper which were impregnated with different taste solutions (four concentrations each for sweet, sour, salty and bitter). These strips are placed on the tongue and subjects are asked to identify the taste quality. After establishing the concentration range of the taste solutions, the test was tried in 69 subjects. Each subject received eighteen taste strips (four concentrations of each taste quality plus two blanks) in a pseudo-randomized sequence. Results from this new procedure correlated significantly with the results of the well established extensive three-drop-technique (r69 = 0.67). Repeated measures indicated good reproducibility of the results for the taste strips (r69 = 0.68). These data suggest the usefulness of this new technique in routine clinical practice. Major advantages are long shelf-life, convenience of administration, short time needed for testing (approximately 8 min), and the possibility to test each side of the tongue separately.

Detecting genuine multipartite continuous-variable entanglement

Abstract: We derive necessary conditions in terms of the variances of position and momentum linear combinations for all kinds of separability of a multiparty multimode continuous-variable state. Their violations can be sufficient for genuine multipartite entanglement, provided the combinations contain both conjugate variables of all modes. Hence, a complete state determination, for example, by detecting the entire correlation matrix of a Gaussian state, is not needed.

A Role for Triggering Receptor Expressed on Myeloid Cells-1 in Host Defense During the Early-Induced and Adaptive Phases of the Immune Response

Abstract: Triggering receptor expressed on myeloid cells (TREM)-1 is a cell surface molecule expressed on neutrophils and monocytes implicated in the propagation of the inflammatory response. To further characterize the function of this molecule in different phases of the immune response, we examined TREM-1 in the context of host defense against microbial pathogens. In primary human monocytes TREM-1 activation did not trigger innate antimicrobial pathways directed against intracellular Mycobacterium tuberculosis , and only minimally improved phagocytosis. However, activation of TREM-1 on monocytes did drive robust production of proinflammatory chemokines such as macrophage inflammatory protein-1α and IL-8. Engagement of TREM-1 in combination with microbial ligands that activate Toll-like receptors also synergistically increased production of the proinflammatory cytokines TNF-α and GM-CSF, while inhibiting production of IL-10, an anti-inflammatory cytokine. Expression of TREM-1 was up-regulated in response to TLR activation, an effect further enhanced by GM-CSF and TNF-α but inhibited by IL-10. Functionally, primary monocytes differentiated into immature dendritic cells following activation through TREM-1, evidenced by higher expression of CD1a, CD86, and MHC class II molecules. These cells had an improved ability to elicit T cell proliferation and production of IFN-γ. Our data suggest that activation of TREM-1 on monocytes participates during the early-induced and adaptive immune responses involved in host defense against microbial challenges.

PENNON: A code for convex nonlinear and semidefinite programming

Abstract: We introduce a computer program PENNON for the solution of problems of convex Nonlinear and Semidefinite Programming (NLP-SDP). The algorithm used in PENNON is a generalized version of the Augmented Lagrangian method, originally introduced by Ben-Tal and Zibulevsky for convex NLP problems. We present generalization of this algorithm to convex NLP-SDP problems, as implemented in PENNON and details of its implementation. The code can also solve second-order conic programming (SOCP) problems, as well as problems with a mixture of SDP, SOCP and NLP constraints. Results of extensive numerical tests and comparison with other optimization codes are presented. The test examples show that PENNON is particularly suitable for large sparse problems.