Showing papers by "University of Duisburg-Essen published in 2005"

Inverse magnetocaloric effect in ferromagnetic Ni-Mn-Sn alloys.

Abstract: The magnetocaloric effect (MCE) in paramagnetic materials has been widely used for attaining very low temperatures by applying a magnetic field isothermally and removing it adiabatically. The effect can also be exploited for room-temperature refrigeration by using giant MCE materials. Here we report on an inverse situation in Ni-Mn-Sn alloys, whereby applying a magnetic field adiabatically, rather than removing it, causes the sample to cool. This has been known to occur in some intermetallic compounds, for which a moderate entropy increase can be induced when a field is applied, thus giving rise to an inverse magnetocaloric effect. However, the entropy change found for some ferromagnetic Ni-Mn-Sn alloys is just as large as that reported for giant MCE materials, but with opposite sign. The giant inverse MCE has its origin in a martensitic phase transformation that modifies the magnetic exchange interactions through the change in the lattice parameters.

Handbook of elliptic and hyperelliptic curve cryptography

Abstract: Preface Introduction to Public-Key Cryptography Mathematical Background Algebraic Background Background on p-adic Numbers Background on Curves and Jacobians Varieties Over Special Fields Background on Pairings Background on Weil Descent Cohomological Background on Point Counting Elementary Arithmetic Exponentiation Integer Arithmetic Finite Field Arithmetic Arithmetic of p-adic Numbers Arithmetic of Curves Arithmetic of Elliptic Curves Arithmetic of Hyperelliptic Curves Arithmetic of Special Curves Implementation of Pairings Point Counting Point Counting on Elliptic and Hyperelliptic Curves Complex Multiplication Computation of Discrete Logarithms Generic Algorithms for Computing Discrete Logarithms Index Calculus Index Calculus for Hyperelliptic Curves Transfer of Discrete Logarithms Applications Algebraic Realizations of DL Systems Pairing-Based Cryptography Compositeness and Primality Testing-Factoring Realizations of DL Systems Fast Arithmetic Hardware Smart Cards Practical Attacks on Smart Cards Mathematical Countermeasures Against Side-Channel Attacks Random Numbers-Generation and Testing References

Mechanisms of B-cell lymphoma pathogenesis

Abstract: Chromosomal translocations involving the immunoglobulin loci are a hallmark of many types of B-cell lymphoma. Other factors, however, also have important roles in the pathogenesis of B-cell malignancies. Most B-cell lymphomas depend on the expression of a B-cell receptor (BCR) for survival, and in several B-cell malignancies antigen activation of lymphoma cells through BCR signalling seems to be an important factor for lymphoma pathogenesis. Recent insights into the lymphomagenic role of factors supplied by the microenvironment also offer new therapeutic strategies.

Martensitic transitions and the nature of ferromagnetism in the austenitic and martensitic states of Ni-Mn-Sn alloys

Abstract: Structural and magnetic transformations in the Heusler-based system ${\mathrm{Ni}}_{0.50}{\mathrm{Mn}}_{0.50\ensuremath{-}x}{\mathrm{Sn}}_{x}$ are studied by x-ray diffraction, optical microscopy, differential scanning calorimetry, and magnetization. The structural transformations are of austenitic-martensitic character. The austenite state has an $L{2}_{1}$ structure, whereas the structures of the martensite can be $10M$, $14M$, or $L{1}_{0}$ depending on the Sn composition. For samples that undergo martensitic transformations below and around room temperature, it is observed that the magnetic exchange in both parent and product phases is ferromagnetic, but the ferromagnetic exchange, characteristic of each phase, is found to be of different strength. This gives rise to different Curie temperatures for the austenitic and martensitic states.

Density-functional theory-symmetry-adapted intermolecular perturbation theory with density fitting: A new efficient method to study intermolecular interaction energies

Abstract: The previously developed DFT-SAPT approach, which combines symmetry-adapted intermolecular perturbation theory (SAPT) with a density-functional theory (DFT) representation of the monomers, has been implemented by using density fitting of two-electron objects. This approach, termed DF-DFT-SAPT, scales with the fifth power of the molecular size and with the third power upon increase of the basis set size for a given dimer, thus drastically reducing the cost of the conventional DFT-SAPT method. The accuracy of the density fitting approximation has been tested for the ethyne dimer. It has been found that the errors in the interaction energies due to density fitting are below 10(-3) kcal/mol with suitable auxiliary basis sets and thus one or two orders of magnitude smaller than the errors due to the use of a limited atomic orbital basis set. An investigation of three prominent structures of the benzene dimer, namely, the T shaped, parallel displaced, and sandwich geometries, employing basis sets of up to augmented quadruple-zeta quality shows that DF-DFT-SAPT outperforms second-order Moller-Plesset theory (MP2) and gives total interaction energies which are close to the best estimates inferred from combining the results of MP2 and coupled-cluster theory with single, double, and perturbative triple excitations.

Magnetoelectric switching of exchange bias.

Abstract: The perpendicular exchange bias field, H(EB), of the magnetoelectric heterostructure Cr2O3(111)/(Co/Pt)(3) changes sign after field cooling to below the Neel temperature of Cr2O3 in either parallel or antiparallel axial magnetic and electric freezing fields. The switching of H(EB) is explained by magnetoelectrically induced antiferromagnetic single domains which extend to the interface, where the direction of their end spins controls the sign of H(EB). Novel applications in magnetoelectronic devices seem possible.

How to unlock regional economies from path dependency? From learning region to learning cluster

Abstract: Since the Industrial Revolution the cyclical processes of rise and fall of regional economies have been accelerating. Many of the specific problems of the falling part of clustering, that is old industrial areas, are related to path dependency and lock-ins. Particularly political lock-ins hinder the necessary restructuring processes in old industrial areas. They can be considered as thick institutional tissues aiming at preserving existing industrial structures and therefore unnecessarily slowing down industrial restructuring and indirectly hampering the development of indigenous potential and creativity. Of the recently born offspring of the family of territorial innovation models, the learning region concept seems to be most focused on overcoming and avoiding political lock-ins in old industrial areas. Most scholars consider learning regions as regional development concepts in which the main actors are strongly, but flexibly, connected with each other and are open both to intraregional and inte...

Clinical and psychological correlates of quality-of-life in polycystic ovary syndrome

Abstract: Objective: Polycystic ovary syndrome (PCOS) has been shown to cause a reduction in quality of life. This study examines the extent of different PCOS symptoms on quality-of-life, psychosocial wellbeing and sexual satisfaction. Methods: Complete metabolic, hormonal, clinical and psychosocial data were obtained from a total of 120 women with PCOS. Patients were compared with 50 healthy women to establish reductions in quality-of-life and emotional well-being. In addition, the correlation between psychosocial variables and the major clinical PCOS features obesity (body mass index (BMI)), excessive body hair (hirsutism score), acne, hyperandrogenism (serum testosterone levels), disturbed insulin regulation (area under the insulin response curve and homeostasis model assessment of insulin resistance), menstrual cycle disturbances and infertility were analyzed. Results: PCOS patients showed significant reductions in quality-of-life, increased psychological disturbances, and decreased sexual satisfaction when compared with healthy controls. BMI and hirsutism scores, but not the presence of acne, were associated with physical aspects of quality-of-life and sexual satisfaction. No clear effect of androgens or insulin resistance on psychosocial variables was detected. Similarly, the type of menstrual cycle disturbances or infertility had no impact on psychological well-being. Conclusion: In PCOS, changes in appearance, particularly obesity and hirsutism, reduce physical dimensions of quality-of-life and decrease sexual satisfaction. The role of biochemical, endocrine and metabolic parameters as well as menstrual irregularities and infertility appeared to be less important. Clinicians should pay attention to the psychosocial dimensions of PCOS on an individual basis, regardless of symptom severity or treatment response.

Pseudomonas aeruginosa lectin LecB is located in the outer membrane and is involved in biofilm formation.

Abstract: Pseudomonas aeruginosa is an opportunistic pathogen which causes a variety of diseases, including respiratory tract infections in patients suffering from cystic fibrosis. Therapeutic treatment of P. aeruginosa infections is still very difficult because the bacteria exhibit high intrinsic resistance against a variety of different antibiotics and, in addition, form stable biofilms, e.g. in the human lung. Several virulence factors are produced by P. aeruginosa, among them the two lectins LecA and LecB, which exert different cytotoxic effects on respiratory epithelial cells and presumably facilitate bacterial adhesion to the airway mucosa. Here, the physiology has been studied of the lectin LecB, which binds specifically to l-fucose. A LecB-deficient P. aeruginosa mutant was shown to be impaired in biofilm formation when compared with the wild-type strain, suggesting an important role for LecB in this process. This result prompted an investigation of the subcellular localization of LecB by cell fractionation and subsequent immunoblotting. The results show that LecB is abundantly present in the bacterial outer-membrane fraction. It is further demonstrated that LecB could be released specifically by treatment of the outer-membrane fraction with p-nitrophenyl α-l-fucose, whereas treatment with d-galactose had no effect. In contrast, a LecB protein carrying the mutation D104A, which results in a defective sugar-binding site, was no longer detectable in the membrane fraction, suggesting that LecB binds to specific carbohydrate ligands located at the bacterial cell surface. Staining of biofilm cells using fluorescently labelled LecB confirmed the presence of these ligands.

Rapid stress reduction and anxiolysis among distressed women as a consequence of a three-month intensive yoga program.

Abstract: Summary Background: Emotional distress is an increasing public health problem and Hatha yoga has been claimed to induce stress reduction and empowerment in practicing subjects. We aimed to evaluate potential effects of Iyengar Hatha yoga on perceived stress and associated psychological outcomes in mentally distressed women. Material/Methods: A controlled prospective non-randomized study was conducted in 24 self-referred female subjects (mean age 37.9±7.3 years) who perceived themselves as emotionally distressed. Subjects were offered participation in one of two subsequential 3-months yoga programs. Group 1 (n=16) participated in the fi rst class, group 2 (n=8) served as a waiting list control. During the yoga course, subjects attended two-weekly 90-min Iyengar yoga classes. Outcome was assessed on entry and after 3 months by Cohen Perceived Stress Scale, State-Trait Anxiety Inventory, Profi le of Mood States, CESD-Depression Scale, Bf-S/Bf-S’ Well-Being Scales, Freiburg Complaint List and ratings of physical well-being. Salivary cortisol levels were measured before and after an evening yoga class in a second sample. Results: Compared to waiting-list, women who participated in the yoga-training demonstrated pronounced and signifi cant improvements in perceived stress (P<0.02), State and Trait Anxiety (P<0.02 and P<0.01, respectively), well-being (P<0.01), vigor (P<0.02), fatigue (P<0.02) and depression (P<0.05). Physical well-being also increased (P<0.01), and those subjects suffering from headache or back pain reported marked pain relief. Salivary cortisol decreased signifi cantly after participation in a yoga class (P<0.05). Conclusions: Women suffering from mental distress participating in a 3-month Iyengar yoga class show significant improvements on measures of stress and psychological outcomes. Further investigation of yoga with respect to prevention and treatment of stress-related disease and of underlying mechanism is warranted.

Predictors and prevalence of paraganglioma syndrome associated with mutations of the SDHC gene.

Abstract: ContextParaganglioma syndrome includes inherited head and neck paragangliomas (HNPs) and adrenal or extra-adrenal pheochromocytomas and are classified according to the susceptibility genes SDHB, SDHC, and SDHD. In contrast with those with germline mutations of the SDHB and SDHD genes, clinical and genetic data on patients with mutations of SDHC are scarce.ObjectiveTo determine the prevalence and clinical characteristics of SDHC mutation carriers compared with patients with SDHB and SDHD mutations and with sporadic cases.Design, Setting, and PatientsGenetic screening for SDHC mutations in an international HNP registry of 121 unrelated index cases and in 371 sporadic cases from a pheochromocytoma registry, conducted January 1, 2001, until December 31, 2004. Identified index cases and affected relatives were clinically evaluated.Main Outcome MeasuresPrevalence of and clinical findings for SDHC mutation–associated HNPs vs those with SDHB and SDHD mutations.ResultsThe prevalence of SDHC carriers was 4% in HNP but 0% in pheochromocytoma index cases. None of the SDHC mutation carriers had signs of pheochromocytoma. We compared HNPs in 22 SDHC mutation carriers with the HNPs of SDHB (n = 15) and SDHD (n = 42) mutation carriers and with 90 patients with sporadic HNPs. Location, number of tumors, malignancy, and age were different: more carotid body tumors were found in SDHC (13/22 [59%]) than in sporadic HNPs (29/90 [32%], P = .03), as well as fewer instances of multiple tumors in SDHC (2/22) than in SDHD (24/42; P<.001), 0 malignant tumors in SDHC vs 6/15 in SDHB (P = .002), and younger age at diagnosis in SDHC than in sporadic HNPs (45 vs 52 years; P = .03).ConclusionsPatients with HNP, but not those with pheochromocytoma, harbor SDHC mutations in addition to those in SDHB and SDHD. In total, more than one quarter of HNP patients carry a mutation in 1 of these 3 genes. Head and neck paragangliomas associated with SDHC mutations are virtually exclusively benign and seldom multifocal. Analysis for germline mutations of SDHC is recommended in apparently sporadic HNP to identify risk of inheritance.

Space-time processing for MIMO communications

Abstract: List of Contributors. Preface. Acknowledgements. 1 MIMO Wireless Channel Modeling and Experimental Characterization (Michael A. Jensen and Jon W. Wallace). 1.1 Introduction. 1.2 MIMO Channel Measurement. 1.3 MIMO Channel Models. 1.4 The Impact of Antennas on MIMO Performance. References. 2 Multidimensional Harmonic Retrieval with Applications in MIMO Wireless Channel Sounding (Xiangqian Liu, Nikos D. Sidiropoulos, and Tao Jiang). 2.1 Introduction. 2.2 Harmonic Retrieval Data Model. 2.3 Identifiability of Multidimensional Harmonic Retrieval. 2.4 Multidimensional Harmonic Retrieval Algorithms. 2.5 Numerical Examples. 2.6 Multidimensional Harmonic Retrieval for MIMO Channel Estimation. 2.7 Concluding Remarks. References. 3 Certain Computations Involving Complex Gaussian Matrices with Applications to the Performance Analysis of MIMO Systems (Ming Kang, Lin Yang, and Mohamed-Slim Alouini). 3.1 Introduction. 3.2 Performance Measures of Multiple Antenna Systems. 3.3 SomeMathematical Preliminaries. 3.4 General Calculations with MIMO Applications. 3.5 Summary. References. 4 Recent Advances in Orthogonal Space-Time Block Coding (Mohammad Gharavi-Alkhansari, Alex B. Gershman, and Shahram Shahbazpanahi). 4.1 Introduction. 4.2 Notations and Acronyms. 4.3 Mathematical Preliminaries. 4.4 MIMO System Model and OSTBC Background.8 4.5 Constellation Space Invariance and Equivalent Array-Processing-Type MIMO Model. 4.6 Coherent ML Decoding. 4.7 Exact Symbol Error Probability Analysis of Coherent ML Decoder. 4.8 Optimality Properties of OSTBCs. 4.9 Blind Decoding of OSTBCs. 4.10 Multiaccess MIMO Receivers for OSTBCs. 4.11 Conclusions. References. 5 Trace-Orthogonal Full Diversity Cyclotomic Space-Time Codes (Jian-Kang Zhang, Jing Liu, and Kon Max Wong). 5.1 Introduction. 5.2 Channel Model with Linear Dispersion Codes. 5.3 Good Structures for LD Codes: Trace Orthogonality. 5.4 Trace-orthogonal LD Codes. 5.5 Construction of Trace Orthogonal LD Codes. 5.6 Design of Full Diversity LD Codes. 5.7 Design of Full Diversity Linear Space-time Block Codes for N

Absolute atomic oxygen density measurements by two-photon absorption laser-induced fluorescence spectroscopy in an RF-excited atmospheric pressure plasma jet

Abstract: The atmospheric pressure plasma jet is a capacitively coupled radio frequency discharge (13.56 MHz) running with a high helium flux (2 m3 h−1) between concentric electrodes. Small amounts (0.5%) of admixed molecular oxygen do not disturb the homogeneous plasma discharge. The jet effluent leaving the discharge through the ring-shaped nozzle contains high concentrations of radicals at a low gas temperature—the key property for a variety of applications aiming at treatment of thermally sensitive surfaces. We report on absolute atomic oxygen density measurements by two-photon absorption laser-induced fluorescence (TALIF) spectroscopy in the jet effluent. Calibration is performed with the aid of a comparative TALIF measurement with xenon. An excitation scheme (different from the one earlier published) providing spectral matching of both the two-photon resonances and the fluorescence transitions is applied.

Simultaneous coordinated tuning of PSS and FACTS damping controllers in large power systems

Abstract: This work deals with the simultaneous coordinated tuning of the flexible AC transmission systems (FACTS) power oscillation damping controller and the conventional power system stabilizer (PSS) controllers in multi-machine power systems. Using the linearized system model and the parameter-constrained nonlinear optimization algorithm, interactions among FACTS controller and PSS controllers are considered. Furthermore, the parameters of the damping controllers are optimized simultaneously. Simulation results of multi-machine power system validate the efficiency of this approach. The proposed method is effective for the tuning of multi-controllers in large power systems.

Fate of triclosan and triclosan-methyl in sewage treatment plants and surface waters.

Abstract: The fate of triclosan in diverse stages of two sewage treatment processes has been determined. The elimination process differed considerably depending on the technology applied in the respective sewage treatment plant (STP). The plant operating with a two-stage biologic (activated sludge) process removed triclosan more efficiently than the STP with a combination of physical and activated sludge process. The treatment in the aeration basin was the dominant elimination mechanism, whereas the final biologic filter was not very effective. The elimination rates for triclosan were 87% and 95%, respectively. These data were compared with emissions of a multitude of STPs in the river Ruhr catchment area as well as triclosan and its known transformation product, triclosan-methyl, in the river. The concentrations of both compounds were between <3 and 10 ng/L in true surface-water samples for triclosan and between 0.3 and 10 ng/L for triclosan-methyl. The STP effluents held higher concentrations (10 to 600 ng/L triclosan). The ratio of triclosan to triclosan-methyl did not change significantly within the longitudinal profile of the river, but diverse STPs discharging to the river exhibited individual triclosan-to-triclosan-methyl ratios. From the riverine concentration data, in-river elimination rates and half-life were estimated.

Assisted reproduction: the epigenetic perspective

Abstract: Developmental pathways in humans and other organisms are buffered against changes in genotype and environment. Therefore, it should not come as a surprise that most of the children conceived by assisted reproduction technology (ART) are healthy, although ART bypasses a lot of biological filters and subjects the gametes and the early embryo to environmental stress. If, however, the buffer breaks down, the development of certain tissues or organs may follow abnormal trajectories. We argue that both normal and abnormal development in children conceived by ART can be explained by epigenetic mechanisms, which control the establishment and maintenance of gene expression patterns in the placenta and fetus. Imprinted genes are of special importance in this respect. There is increasing evidence that genetic factors in infertile couples as well as environmental factors (hormones and culture media) can have adverse effects on epigenetic processes controlling implantation, placentation, organ formation and fetal growth. In addition, loss of epigenetic control may expose hidden genetic variation.

Combined analysis of ZAP-70 and CD38 expression as a predictor of disease progression in B-cell chronic lymphocytic leukemia.

Abstract: Prognostic predictions in B-cell chronic lymphocytic leukemia (B-CLL) at early clinical stage are based on biological disease parameters, such as ZAP-70 and CD38 protein levels, genomic aberrations as well as immunoglobulin variable heavy chain gene (IgV(H)) mutation status. In the current study, ZAP-70 and CD38 expressions were examined by flow cytometry in 252 patients with B-CLL. Cytoplasmic ZAP-70 expression in more than 20% (ZAP-70(+)) and surface CD38 expression on more than 30% (CD38(+)) of B-CLL cells were associated with an unfavorable clinical course. The levels of ZAP-70 and CD38 did not change over time in the majority of patients where sequential samples were available for analysis. Combined analysis of ZAP-70 and CD38 yielded discordant results in 73 patients (29.0%), whereas 120 patients (47.6%) were concordantly negative and 59 patients (23.4%) were concordantly positive for ZAP-70 and CD38 expression. Median treatment-free survival times in patients whose leukemic cells were ZAP-70(+)CD38(+) was 30 months as compared to 130 months in patients with a ZAP-70(-)CD38(-) status. In patients with discordant ZAP-70/CD38 results, the median treatment-free survival time was 43 months. Thus, ZAP-70 and CD38 expression analyses provided complementary prognostic information identifying three patient subgroups with good, intermediate and poor prognosis. Over-representation of high-risk genomic aberrations such as 17p deletion or 11q deletion and distribution of the IgV(H) mutation status in B-CLL discordant for ZAP-70/CD38 pointed toward a distinct biologic background of the observed disease subgroups. This finding was also supported by microarray-based gene expression profiling in a subset of 35 patients. The expression of 37 genes differed significantly between the three groups defined by their expression of ZAP-70 and CD38, including genes that are involved in regulation of cell survival and chemotherapy resistance.

CNGB3 mutations account for 50% of all cases with autosomal recessive achromatopsia

Abstract: Achromatopsia is a congenital, autosomal recessively inherited disorder characterized by a lack of color discrimination, low visual acuity (<0.2), photophobia, and nystagmus. Mutations in the genes for CNGA3, CNGB3, and GNAT2 have been associated with this disorder. Here, we analyzed the spectrum and prevalence of CNGB3 gene mutations in a cohort of 341 independent patients with achromatopsia. In 163 patients, CNGB3 mutations could be identified. A total of 105 achromats carried apparent homozygous mutations, 44 were compound (double) heterozygotes, and 14 patients had only a single mutant allele. The derived CNGB3 mutation spectrum comprises 28 different mutations including 12 nonsense mutations, eight insertions and/or deletions, five putative splice site mutations, and three missense mutations. Thus, the majority of mutations in the CNGB3 gene result in significantly altered and/or truncated polypeptides. Several mutations were found recurrently, in particular a 1 bp deletion, c.1148delC, which accounts for over 70% of all CNGB3 mutant alleles. In conclusion, mutations in the CNGB3 gene are responsible for approximately 50% of all patients with achromatopsia. This indicates that the CNGB3/ACHM3 locus on chromosome 8q21 is the major locus for achromatopsia in patients of European origin or descent.

Impact of distributed generation on the stability of electrical power system

Abstract: This paper aims at analysing the potential impacts that distributed generation might have on the stability of electrical power networks. In particular, the performance of a power system with significant penetration of distributed resources is described to assess different types of stability of the bulk network. For this purpose, a hypothetical network is simulated, assuming a large number of fuel cells and micro-turbines as dispersed units in the low-voltage area. The investigation is carried out at constant load demands but with different contributions from fuel cells and micro-turbines. Thus, the rated and supplied powers of the conventional synchronous generators are adjusted to achieve the power balance in the network. With each penetration level of the distributed generation, the performance of the network is studied and different stability classes are analysed. The results are compared with the performance of the network without any distributed generation, as a reference case, to highlight the influence of penetration levels of such units on the stability of the entire network.

Distributive Lattices, Bipartite Graphs and Alexander Duality

Abstract: A certain squarefree monomial ideal HP arising from a finite partially ordered set P will be studied from viewpoints of both commutative algbera and combinatorics. First, it is proved that the defining ideal of the Rees algebra of HP possesses a quadratic Grobner basis. Thus in particular all powers of HP have linear resolutions. Second, the minimal free graded resolution of HP will be constructed explicitly and a combinatorial formula to compute the Betti numbers of HP will be presented. Third, by using the fact that the Alexander dual of the simplicial complex ? whose Stanley---Reisner ideal coincides with HP is Cohen---Macaulay, all the Cohen---Macaulay bipartite graphs will be classified.

Complex H2AX phosphorylation patterns by multiple kinases including ATM and DNA-PK in human cells exposed to ionizing radiation and treated with kinase inhibitors

Abstract: In eukaryotic cells, DNA double strand breaks (DSBs) cause the prompt phosphorylation of serine 139 at the carboxy terminus of histone H2AX to generate gamma-H2AX, detectable by Western blotting or immunofluorescence. The consensus sequence at the phosphorylation site implicates the phosphatidylinositol 3-like family of protein kinases in H2AX phosphorylation. It remains open whether ATM (ataxia telangiectasia mutated) is the major H2AX kinase, or whether other members of the family, such as DNA-PK (DNA dependent protein kinase) or ATR (ATM and Rad3 related), contribute in a functionally complementary manner. To address this question, we measured global H2AX phosphorylation in cell lysates and foci formation in individual cells of either wild type or mutant (ATM or DNA-PK) genetic background. Normal global phosphorylation kinetics is observed after irradiation in cells defective either in ATM or DNA-PK alone, suggesting a complementary contribution to H2AX phosphorylation. This is further supported by the observation that initial H2AX phosphorylation is delayed when both kinases are inhibited by wortmannin, as well as when ATM is inhibited by caffeine in DNA-PK deficient cells. However, robust residual global phosphorylation is detectable under all conditions of genetic or chemical inhibition suggesting the function of additional kinases, such as ATR. Treatment with wortmannin, caffeine, or UCN-01 produces a strong DNA-PK dependent late global hyperphosphorylation of H2AX, uncoupled from DNA DSB rejoining and compatible with an inhibition of late steps in DNA DSB processing. Evaluation of gamma-H2AX foci formation confirms the major conclusions made on the basis of global H2AX phosphorylation, but also points to differences particularly several hours after exposure to IR. The results in aggregate implicate DNA-PK, ATM and possibly other kinases in H2AX phosphorylation. The functional significance and the mechanisms of coordination in space and time of these multiple inputs require further investigation.

Porous Polypropylene Membranes with Different Carboxyl Polymer Brush Layers for Reversible Protein Binding via Surface-Initiated Graft Copolymerization

Abstract: Photoinitiated surface-selective graft copolymerization onto polypropylene (PP) microfiltration membranes was performed using two different methods for coating the photoinitiator, benzophenone (BP), on the membrane surface. An already established adsorption method and a novel method based on preswelling of the PP in heptane, subsequent solvent exchange, and thus entrapping of the BP in the surface layer of the PP had been evaluated. With acrylic acid (AA) as the monomer, functional polymer brush structures on the entire membrane pore surface were obtained. Further variations of the grafted layer had been achieved by copolymerization of AA with acryl amide (AAm) and methylene bisacrylamide (MBAA). Characterization had been done mainly by detailed measurements of membrane permeability including pH dependency as well as the reversible binding of a protein (lysozyme, Lys) under membrane chromatography conditions. Compared with BP adsorption, the BP entrapping method yielded a less dense grafted layer with lon...

A generalized ESPRIT approach to direction-of-arrival estimation

Abstract: A new spectral search-based direction-of-arrival (DOA) estimation method is proposed that extends the idea of the conventional ESPRIT DOA estimator to a much more general class of array geometries than assumed by the conventional ESPRIT technique. A computationally efficient polynomial rooting-based search-free implementation of the proposed algorithm is also developed.