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Domain wall pinning is the coercivity mechanism of permanent magnets used in high temperature applications. In SmCo based magnets domain walls get trapped at the cellular precipitation structure causing a high coercive field. The motion of domain walls and their propagation velocity are important in soft magnets as used in sensor applications. A finite element micromagnetic algorithm was developed to study the motion of domain walls in complex microstructures. The cellular microstructure of SmCo magnets or the cylindrical soft wires can be easily built using tetrahedral finite elements. The pinning of the domain walls has been studied for different material compositions. Attractive and repulsive domain wall pinning are observed and their behaviour for increasing thickness of the precipitation structure is explained. The motion of domains in magnetic nanowires was calculated using adaptive mesh refinement. The wall velocity strongly depends on the domain wall structure. Transverse and vortex walls have been observed and their velocity in wires of different thickness has been studied.

Minimum energy paths and energy barriers are calculated for complex micromagnetic systems. The method is based on the nudged elastic band method and uses finite-element techniques to represent granular structures. The method was found to be robust and fast for both simple test problems as well as for large systems such as patterned granular media. The method is used to estimate the energy barriers in CoCr-based perpendicular recording media.

Aromatic phosphate esters such as triphenyl phosphate, tricresyl phosphate (TCP), and tri(tert-butylphenyl) phosphate, have been degraded in the presence of pure iron or metal alloys such as M-50 or 52100 steel. Among these volatile degradation products are those generated from the addition of an aromatic ring to the phosphate ester. Other products, which have been identified, include substituted biphenyls and diphenyl ethers derived from the decomposition of the above-mentioned addition product. Still other products are fused ring aromatic compounds such as anthracene, which arise from secondary reactions of the initial decomposition reactions. The decomposition reactions leave a nonvolatile phosphate film on the surface of the metal. Characterization of the film with Auger spectroscopy suggests iron phosphate as the product. X-ray photoelectron spectroscopy shows the presence of a bound organic layer at the surface. A mechanism that explains many of the decomposition products and the formation of a boun...

The magnetization reversal process of magnetic nano-wires was investigated using a moving mesh finite element method. The nucleation and expansion of reversed domains is calculated by solving the Gilbert equation of motion. For a wire diameter of d=20 nm either a transverse wall or a vortex wall is formed, depending on the strength of the initial applied field. Once a reversed domain is nucleated, the wall configuration remains the same during the complete reversal process. The vortex wall moves faster than the transverse wall. The domain wall velocities are in the order of 300–800 m/s for an external field in the range from 300 to 600 kA/m for a Gilbert damping constant α=1. The domain wall velocity increases with increasing wire diameter and decreasing damping constant, reaching 2000 m/s for d=40 nm, α=0.05, and an applied field of 250 kA/m.

A detailed description for the solution of the Landau–Lifshitz–Gilbert equation with the finite element method is given. The use of implicit time integration schemes with proper preconditioning is reported. Simulations of a single-phase magnetic nanoelement without surface roughness and a magnetic nanoelement with a granular structure are performed to investigate the influence of the microstructure on the numerical behavior. Nanoelements with a granular structure cause an inhomogeneous computational grid. In granular systems preconditioning for time integration speeds up the simulations by three orders of magnitude as compared to conventional time integration schemes like the Adams method. r 2002 Elsevier Science B.V. All rights reserved.

An integrated, stacked microlaboratory for performing automated electric-field-driven immunoassays and DNA hybridization assays was developed. The stacked microlaboratory was fabricated by orderly laminating several different functional layers (all 76 x 76 mm(2)) including a patterned polyimide layer with a flip-chip bonded CMOS chip, a pressure sensitive acrylic adhesive (PSA) layer with a fluidic cutout, an optically transparent polymethyl methacrylate (PMMA) film, a PSA layer with a via, a patterned polyimide layer with a flip-chip bonded silicon chip, a PSA layer with a fluidic cutout, and a glass cover plate layer. Versatility of the stacked microlaboratory was demonstrated by various automated assays. Escherichia coli bacteria and Alexa-labeled protein toxin staphylococcal enterotoxin B (SEB) were detected by electric-field-driven immunoassays on a single chip with a specific-to-nonspecific signal ratios of 4.2:1 and 3.0:1, respectively. Furthermore, by integrating the microlaboratory with a module for strand displacement amplification (SDA), the identification of the Shiga-like toxin gene (SLT1) from E. coli was accomplished within 2.5 h starting from a dielectrophoretic concentration of intact E. coli bacteria and finishing with an electric-field-driven DNA hybridization assay, detected by fluorescently labeled DNA reporter probes. The integrated microlaboratory can be potentially used in a wide range of applications including detection of bacteria and biowarfare agents, and genetic identification.

Although there is consensus in the international literature on the benefits of using perioperative antibiotic prophylaxis (PAP), there is still considerable scope for improving its use in many hospitals.In this study, data on the practice of PAP were recorded in eight German hospitals within the framework of a prospective controlled interventional study for the surveillance and prevention of nosocomial infections.A total of 627 surgical procedures (appendectomies, other colorectal procedures, total prosthetic hip replacement) were assessed; 397 with PAP and 224 without PAP; six procedures could not be evaluated. Of the 397 PAP recorded, only 180 (45.3%) were performed correctly in accordance with international standards as a preoperative single dose (19/59 PAP in appendectomies, 72/188 PAP in other colorectal procedures, 89/150 PAP in total prosthetic hip replacement).There is still great uncertainty regarding the point in time at which PAP should be administered and its duration. Additional efforts are necessary to improve PAP in accordance with published evidence-based guidelines.

This paper highlights the development of carbon matrix-carbon fiber (C-C) composite bearing cages for high temperature gas turbine applications. Benefits of C-C cages under high-speed, high-temperature conditions are documented with experimental results. The experimental results show that C-C cages offer substantial reduction in heat generation compared to metal cages at the same operating conditions, and C-C cages enable much higher DN operation in the absence of liquid lubrication. The improved performance of C-C cages over conventional metal cages is largely attributed to the inherent properties of C-C composites: 1. Low density to reduce centrifugal speed effects; 2. Excellent thermal conductivity for a non-metal; 3. Low friction under marginal lubrication conditions; 4. Low wear rates compared to other self-lubricating cage materials; and 5. Low coefficient of thermal expansion to avoid seizure in high thermal gradient conditions. Presented at the 56th Annual Meeting in Orlando, Florida May 20–24, 2001

Previous results obtained in this laboratory have shown that tricresyl phosphate vapors preferentially react with iron and its oxides in the order of the oxidation state (reaction rate of Fe3+≫Fe2+>Fe+>Fe). The reaction kinetics is attributed to a Lewis acid, FenOm, reacting with the basic phosphate ester, (ArO)3PO. The current research further investigates the role of the oxide in the reaction of the aryl phosphate lubricants, tricresyl phosphate and tertiary-butyl phenyl phosphate, with 1010 steel coupons. To measure the relative effect of iron oxides, some coupons were exposed to 400 °C air for 1 h and then sealed under vacuum in glass tubes with 25 mg of lubricant. Other samples were sealed under vacuum without the oxidation step. All of the sealed test tubes with lubricant and foil were heated to a temperature of 475 °C and held for different lengths of time. Afterwards, the coupons were analyzed with Fourier infrared microscopy, Auger electron spectroscopy, Raman spectroscopy, and scanning electron microscopy. In the case of the pre-oxidized sample, a nodular film was formed that contained organic species and iron polyphosphate. For samples that were not pre-oxidized, simple ionic iron phosphate was formed. In another work it was found that nodular structure formation is important to obtain good lubrication. This type of film forms on iron surfaces and not on surfaces passivated by inert oxide films, i.e., aluminum, nickel, and high chrome content alloys. The reaction of tricresyl phosphate with other metals and their oxides were also examined and found to correlate well with iron.

Aims To assess the willingness to utilise follow-up eye care services among participants of community vision screenings in rural villages surrounding Chennai. Methods Vision screening participants aged ≥40 years were selected by systematic sampling and were invited to respond to a pretested verbal survey with close-ended questions before undergoing screening. Results Two hundred and ninety-two people responded. Among the respondents, 50.3% reported experiencing an eye problem, and 53% of these individuals had never had an eye examination. Acceptance rate for eye surgery, medications, and eyeglasses among the respondents was 59.2%, 52.7% and 90.8%, respectively. These acceptances were not associated with sex, age, or employment; medication acceptance was inversely associated with literacy. Surgery acceptance and medication acceptance were associated with area of residence. Presence of another chronic disease was a predictor for surgery acceptance among respondents experiencing eye problems. Conclusions Maintaining consistent quality of services delivered is crucial for increasing uptake of existing eye care services. Educational interventions may increase eye care service usage by targeting all demographic subgroups of rural populations equally. Additional interventions should be offered to patients without previous exposure to the healthcare system.

Compliance with European working time regulations in surgical practice has resulted in an increase in the number of clinicians caring for individual patients and subsequently an increase in the frequency of handovers. In 2007, the Royal College of Surgeons of England produced guidelines on the minimum data-set for 'safe handover'. This audit examined compliance with these guidelines before and after adopting a more detailed electronic handover 'template' with the intention of improving handover quality and patient safety.Pre-existing surgical 'take' electronic handover sheets were reviewed daily for two weeks to assess compliance with published guidance. A new proforma was introduced, training delivered and compliance re-audited. χ2 analysis was performed to determine statistical significance.The handovers of 118 patients were audited before, and 114 after, the implementation of the new proforma. Name and responsible consultant were recorded in all cases. Age (52% vs. 85%, p=0.01), location (77% vs. 95%, p=0.01), admission date (0% vs. 39%, p=0.01), medical history (82% vs. 94%, p=0.01), diagnosis (55% vs. 93%, p=0.01) and management plan (81% vs. 97%, p=0.01) showed a statistically significant improvement with the new proforma. Presenting complaint (93% vs. 98%) and investigation (90% vs. 90%) data remained good. Review frequency (5%vs.11%) and outstanding tasks (21% vs. 27%) were poorly documented.Significant improvement was seen in the completeness of information handed-over following the introduction of the new proforma with likely positive implications for patient safety and standard of care. Opportunity for improvement still remains however, and more specific focussed tuition for trainees is required.

Alkaline phosphatase (AP) isozymes are present in a wide range of species from bacteria to man and are capable of dephosphorylation and transphosphorylation of a wide spectrum of substrates in vitro. In humans, four AP isozymes have been identified—one tissue-nonspecific (TNAP) and three tissue-specific—named according to the tissue of their predominant expression: intestinal (IAP), placental (PLAP) and germ cell (GCAP) APs. Modulation of activity of the different AP isozymes may have therapeutic implications in distinct diseases and cellular processes. For instance, changes in the level of IAP activity can affect gut mucosa tolerance to microbial invasion due to the ability of IAP to detoxify bacterial endotoxins, alter the absorption of fatty acids and affect ectopurinergic regulation of duodenal bicarbonate secretion. To identify isozyme selective modulators of the human and mouse IAPs, we developed a series of murine duodenal IAP (Akp3-encoded dIAP isozyme), human IAP (hIAP), PLAP, and TNAP assays. High throughput screening and subsequent SAR efforts generated a potent inhibitor of dIAP, ML260, with specificity for the Akp3-, compared to the Akp5- and Akp6-encoded mouse isozymes.

We have developed the first prototypes of a three-dimensional, electrophoretically driven microlaboratory for the analysis of proteins and DNA. By selecting the appropriate spacing and geometrical configuration, oligonucleotides were transported, in a controlled, rapid fashion, by electrophoresis in free-space. Transport efficiencies over 2 mm distances exceeded 70%. Electrodes of similar design were combined with an electronically addressed DNA hybridization chip to form a fully electrophoretic microlaboratory. In this instance, gold-plated copper electrodes were patterned on a 2 mil thick polyimide substrate. This polyimide layer was stiffened with 20 mil of polyimide to provide support for flip-chip bonding of our standard 100-site Nanochip. This composite structure illustrated three-dimensional transport of target oligonucleotides, through a via in the polyimide, along a series of electrodes and onto the diagnostic chip. Upon reaching the diagnostic chip, electronic hybridization was performed for a competitive reverse dot blot assay. The electronic assay showed a specific to nonspecific ratio in excess of 20:1. These results suggested that this type of structure might be of practical consequence with the development of a microlaboratory for biowarfare applications.

OBJECTIVES Pharmacokinetics and tolerability of acetyl starch (ACS) in comparison to hydroxyethyl starch (HES) were investigated after repeated intravenous infusions. METHODS AND COHORTS: A 500 ml solution of ACS (n = 8) or HES (n = 9) was infused to male volunteers (Age 25-42 Years) over four hours on five consecutive days. RESULTS Comparing the pharmacokinetic parameters, marked differences were found between ACS and HES. A continuos increase of Cmax, AUC0-24 and t1/2 over the five days caused by administration of HES was due to an accumulation of HES in serum. However, after administration of ACS all these parameters remained unaltered. The repeated infusion of 50 g ACS did not cause any changes of the acid-base-status. The influence of ACS on the coagulation parameters was comparable to that of HES and due to dilution effects. The acetic acid concentration increased up to 2.96 +/- 0.67 mg/dl following ACS infusion. The blood glucose concentration was not influenced by the infusion of HES or of ACS. The repeated ACS infusions were well tolerated. In contrast to HES, ACS did not accumulate in serum. CONCLUSION According to these data ACS is an alternative to HES for volume replacement. Well-known side effects due to long storage of HES in tissues may not occur following application of ACS. However, the wide usage of ACS is restricted by the limited stability of ACS solutions at room temperature. ACS solutions are thus only stable during storage at lower temperatures.

Ziel der perioperativen Antibioticaprophylaxe (PAP) ist es, postoperative Komplikationen zu reduzieren. 1994 wurde von US-amerikanischen Fachgesellschaften ein Qualitatsstandard fur die PAP entwickelt, wobei die einzelnen Empfehlungen nach ihrem Evidenzgrad in verschiedene Kategorien eingeteilt wurden. Erganzt durch die Ergebnisse neuerer randomisierter, kontrollierter Studien sollen die Empfehlungen in tabellarischer Ubersicht dargestellt werden.

Microelectronic DNA chip devices that contain planar arrays of microelectrodes have been developed for multiplex DNA hybridization and a variety of genomic research and DNA diagnostic applications. These devices are able to produce almost any desired electric field configuration on their surface. This ability to produce well-defined electric fields allows charged molecules (DNA, RNA, proteins, enzymes, antibodies, nanobeads, and even micron scale semiconductor devices) to be electrophoretically transported to or from any microlocation on the planar surface of the device. Of key importance to the device function is the permeation layer which overcoats the microelectrodes. The permeation layer is generally a porous hydrogel material that allows water molecules and small ions (Na+, CI-, etc.) to freely contact the microelectrode surface, but impedes the transport of the larger analytes (oligonucleotides, DNA, RNA, proteins, etc.). The permeation layer prevents the destruction of DNA at the active microelectrode surface, ameliorates the adverse effects of electrolysis products on the sensitive hybridization reactions, and serves as a porous support structure for attaching DNA probes and other molecules to the array. In order to maintain rapid transport of DNA molecules, facilitate hybridization, and work within constrained current and voltage ranges, low conductance buffers and various electronic pulsing scenarios have also been developed. These active microelectronic array devices allow electrophoretic fields to be used to carry out accelerated DNA hybridization reactions and to improve selectivity for single nucleotide polymorphism (SNP), short tandem repeat (STR), and point mutation analysis.

The high temperature rolling contact endurance, friction, and wear of 16 cesium-based compounds with solid lubricating properties were investigated on silicon nitride (Si3N4). Some were also investigated on bearing tool steels and several state-of-the-art high temperature solid lubricants were investigated for comparison. Experiments were conducted in air at temperatures up to 650°C, contact stresses up to 4.34 GPa, and a pure rolling surface speed of 1.8 m/s. Although all of the cesium-based compounds exhibited self-lubricating properties, the best overall performance was achieved with a cesium silicate reaction film formed in-situ (Cs2O·xSiO2) and a hydrated cesium silicate bonded coating (Cs2O·3SiO2·nH2O). Bonded coatings of cesium oxythiotungstate + tungsten disulfide mixture (Cs2WOS3 + WS2) and cesium hydroxide (CsOH) also performed well. It is hypothesized that high temperature chemical reactions between the cesium-containing compounds and the silicon nitride surface form a lubricious cesium silicat...

Energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and Auger electron spectroscopy (AES) were used to characterize the wear surfaces of selected samples from Part 1 of the authors study. Results are presented for films generated on silicon nitride (Si3N4) originally coated with cesium oxytrithiotungstate (Cs2WOS3), cesium sulfate (Cs2SO4), and a hydrated cesium silicate (Cs2O·3SiO2·nH2O), all applied in a sodium silicate binder (Na2SiO3). Results show the presence of mostly Si, O, and Cs within the wear tracks of post-tested specimens. In some cases, W and S were not detected on samples that originally contained these elements, suggesting that decomposition had taken place. To simulate the reactions that might occur in a tribo-contact, mixtures of Si3N4 and Cs2WOS3 powders were heated in air to 700°C and analyzed using XPS and Bremsstrahlung-excited AES. It was found that Cs2WOS3 accelerates the formation ofSiO2 on Si3N4 under static conditions. These results support our h...

Auger depth profile data, obtained from vapor-lubricated T15 bearing steel, were modeled using the solution for diffusion in a semi-infinite pair. A tertiary-butyl phenyl phosphate was used as the vapor lubricant. The primary species undergoing diffusion are iron and carbon. The objective of the experiment was to determine the order of magnitude of the diffusion coefficient and to qualitatively assess what types of diffusion mechanisms are involved. The experimental results indicate that the diffusion profile travels at a velocity equal to the bearing wear rate under dynamic conditions. This is possible if iron diffusions at a faster rate than carbon, i.e., the Kirkendall effect. Analyses of the data were performed using Darken's equations. The results indicate that the diffusion coefficient of iron is of the order of 1 × 10−14 cm2/s at test temperatures of 370° and 430°C. Diffusion is thought to occur via the migration of iron cations through an anionic lattice of polyphosphate and phosphite, i.e., catio...

Infrared microscopy (μ-FTIR), Raman spectroscopy, Auger electron spectroscopy (AES), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to characterize bearing surfaces lubricated from the vapor phase. Results are presented for surface films generated with a tertiary-butyl phenyl phosphate (TBPP) and a polyphenylether (5P4E). Infrared bands consistent with inorganic poly-phosphates and phosphites were detected in deposition films generated with the TBPP lubricant. Raman shifts consistent with graphite of short range order were detected in films deposited by both lubricants. However, specimens lubricated by the 5P4E had several Raman shifts consistent with Fe2O3 and Fe3O4. Iron oxides were not detected in deposition films generated with the TBPP lubricant. AES depth profiles indicate a predominant mixture of iron and carbon in the TBPP deposition film; whereas, the 5P4E film predominately consists of iron and oxygen. Localized corrosion pitting generated with the TBPP lub...

In summary,Acinetobacter colonization or infection may originate from the patients' own flora under the pressure of antimicrobial selection, the hands of staff members, or contaminated equipment. Transmission ofAcinetobacter strains between patients occurs primarily via the hands of health care workers. In outbreak situations, colonized or infected patients and the inanimate environment, which can be secondarily contaminated, are the main reservoirs in the hospital setting for crosstransmission. However, colonized or infected patients seem to be the most important source of cross-contamination, as epidemic strains spread easily throughout different wards. Especially in prolonged outbreaks in which control efforts such as proper hand washing, glove changing, and restriction of antimicrobial agents are ineffective and specific sources such as contaminated equipment are not identified, the source of the epidemic strain is likely the patients' inanimate dry environment [45, 48]. In outbreak situations it is necessary that isolatedAcinetobacter strains are identified to the genomic species level and then typed before epidemiological conclusions can be drawn, becauseAcinetobacter spp. are ubiquitous organisms [3, 31].

The liquid oil lubrication system of current aircraft jet engines accounts for approximately 10–15% of the total weight of the engine. It has long been a goal of the aircraft gas turbine industry to reduce this weight. Vapor-Phase Lubrication (VPL) is a promising technology to eliminate liquid oil lubrication. The current investigation resulted in the first gas turbine to operate in the absence of conventional liquid lubrication. A phosphate ester, commercially known as DURAD 620B, was chosen for the test. Extensive research at Wright Laboratory demonstrated that this lubricant could reliably lubricate railing element bearings in the gas turbine engine environment. The Allison T63 engine was selected as the test vehicle because of its small size and bearing configuration. Specifically, VPL was evaluated in the number eight bearing because it is located in a relatively hot environment, in line with the combustor discharge, and it can be isolated from the other bearings and the liquid lubrication system. The bearing was fully instrumented and its performance with standard oil lubrication was documented. Results of this baseline study were used to develop a thermodynamic model to predict the bearing temperature with VPL. The engine was then operated at a ground idle condition with VPL with the lubricant misted into the #8 bearing at 13 ml/hr. The bearing temperature stabilized at 283°C within 10 minutes. Engine operation was continued successfully for a total of one hour. No abnormal wear of the rolling contact surfaces was found when the bearing was later examined. Bearing temperatures after engine shutdown indicated the bearing had reached thermodynamic equilibrium with its surroundings during the test. After shutdown bearing temperatures steadily decreased without the soakback effect seen after shutdown in standard lubricated bearings. In contrast, the oil lubricated bearing ran at a considerably lower operating temperature (83°C) and was significantly heated by its surroundings after engine shutdown. In the baseline tests, the final bearing temperatures never reached that of the operating VPL system.Copyright © 1997 by ASME

The relative effects of several vapor lubrication parameters on bearing performance were examined using a ball-on-rod tester. Lubricants included in the evaluation were a tertiary-butylphenyl phosphate (TBPP), a 2 cSt polyalphaolefin blended with 15 percent TBPP (PAO+), the TBPP blended with 33 percent tributyl phosphate (TBPP+), a cyclophosphazine (X-1P), a polyphenylether (5P4E), and a perfluoroalkylether (Z). Parameters included in the study were bearing temperature, vapor concentration, and vapor temperature. Additionally, a solid lubricant coating was included to improve the bearing performance under cold-start conditions. The lubricants containing phosphorus demonstrated the best high temperature performance. The TBPP lubricant failed shortly after test at 650°C., while the X-1P lubricant performed satisfactorily over an eight-hour period at 650°C. The TBPP+ lubricant demonstrated the widest temperature range capability, with 600°C operation and a projected pump-ability point of–-45°C. Lubricant con...

Material screening tests have been performed with four candidate vapor phase lubricants under rolling contact conditions at bearing test temperatures of 370°C. The lubricants evaluated were t-butyl phenyl phosphate (TBPP), polyalphaolefin (PAO), cyclophosphazene (X-1P), and PAO blended with 15 percent TBPP (PAO+). Factorial analyses were used to separate the effects of lubricant; bearing steel, T15 vs. thin dense chrome-coated T15; cage material, AISI 4340 vs. Monel 400; and ball material, T15 vs. NBD 200 Si3N4. Response variables included in the analyses were the bearing friction coefficient, wear rate, and life under accelerated conditions. The type of lubricant was significant at the 90 percent confidence level for all three response variables, with the PAO+ and TBPP showing the best results. In general, bearing materials containing Fe showed improved performance over materials which do not contain Fe at the bearing surface. Presented at the 51st Annual Meeting in Cincinnati, Ohio May 19–23, 1996

The influence of hydronephrosis (6-10 wk) on the renal vascular response to arginine vasopressin (AVP) was assessed, using isolated perfused normal and hydronephrotic rat kidneys. In normal kidneys, AVP (0.3 nM) reduced renal perfusate flow (RPF) by 55 +/- 7% (P < 0.01). AVP-induced decrements in RPF were reversed partially by diltiazem (10 microM) and completely by 10 nM of an AVP (V1)-receptor antagonist (AVPX). In hydronephrotic kidneys, AVP reduced RPF by 81 +/- 2% (P < 0.01) and constricted afferent (AA) and efferent arterioles (EA) by 33 +/- 3 (P < 0.01) and 33 +/- 5% (P < 0.01), respectively. The addition of diltiazem altered neither RPF nor vessel diameters. Administration of AVPX recovered RPF, AA, and EA diameters. When hydronephrotic kidneys were pretreated with thromboxane (Tx) inhibitors, AVP reduced RPF by 62 +/- 5% (P < 0.01) and constricted AAs and EAs by 26 +/- 2 (P < 0.01) and 17 +/- 3% (P < 0.05), respectively. Under Tx blockade, diltiazem partially reversed the AVP-induced reduction in RPF and restored the decrements in AA diameter. Subsequent addition of AVPX returned RPF and EA diameter. Our data indicate that AVP elicits substantial renal microvascular constriction and suggest that AVP stimulates Tx production in hydronephrotic kidneys, thereby altering renal vascular responsiveness to this peptide.

To investigate ocular manifestations of human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) in a population in central south China during a time of highly active antiretroviral therapy (HAART).A cross-sectional study in central south China was performed between June 2009 and April 2010. Ocular examinations were performed on recruited patients with HIV/AIDS. Systemic information (including CD4+ T cell count) was also collected where possible.Among 1041 patients (2082 eyes) with HIV/AIDS enrolled in our study, we found a broad spectrum of ocular manifestations related to HIV/AIDS. The prevalence of HIV-associated ocular disease was 23.73% (247 patients). Of those with ocular complications, 87.85% had CD4 counts200 cells/µL. HIV retinopathy (12.68%) was the most common HIV-associated ocular finding, followed by cytomegalovirus retinitis (6.72%). Prevalences of visual impairment and blindness were 7.59% and 0.77%, respectively.This epidemiologic study shows the spectrum of ocular lesions associated with HIV/AIDS in central south China. Our findings highlight the need for routine ophthalmic examinations in this population, even in patients who are asymptomatic, especially those at high risk, in the era of HAART.

In this paper, we test the performance and validity of a semi-implicit time-integration scheme, originally applied in quantum dynamics, for use in micromagnetics. The attempt frequency and energy barriers are calculated for Co nanoparticles. Moreover, a fit of the relaxation time to the Arrhenius-Neel law is presented. The semi-implicit time-integration method is very robust and allows time steps up to 3 ps at a temperature of 50 K.

The switching speed of a granular perpendicular recording medium is investigated using finite-element micromagnetic calculations. The switching behavior sensitively depends on the intergrain exchange coupling, the grain-size distribution, and the degree of alignment of easy axes. These effects are investigated using subgrain discretization. In irregular microstructures the switching time decreases considerably with decreasing intergrain exchange.

Langevin micromagnetics treats finite temperature effects by adding a thermal fluctuation field, H th , to the effective field. If combined with the finite element method a large system of stochastic differential equations (SDEs) has to be solved. In this paper, a new semi-implicit method is used to treat the system of SDEs on magnetic sensor elements. Fluctuations are of immense importance in recording industry because they lead to instabilities and also increase the noise. The results show that according to the model conclusions the fluctuations of the magnetization increase slightly with the temperature.

Fast boundary integration methods are implemented to increase the efficiency of the calculation of the magnetostatic interaction of magnetic particles. We test the treecode algorithm and a hierarchical matrices method to improve the original used matrix-vector multiplication with a fully populated matrix. We compare the CPU-time used for the setup phase and for the matrix-vector multiplication, as well as the required storage.

Exchange bias in polycrystalline IrMn/NiFe was found at perfectly compensated interfaces. The energy associated with unidirectional anisotropy is stored in lateral domain walls in the antiferromagnet. In addition to exchange bias, this mechanism leads to a training effect. The bias field shows a maximum of μ0Hb=4 mT at an antiferromagnetic layer thickness of 22 nm. The coercivities are on the order of μ0Hc=10 mT. The coercive field increases with decreasing intergrain exchange interactions within the ferromagnet.

The calculation of energy barriers between stable equilibrium states in strongly interacting systems requires the calculation of saddle points in high dimensional energy landscapes. We combine the nudged elastic band method with finite element micromagnetics to calculate optimal paths, giving a global view of thermal switching in antiferromagnetically coupled media. Energy barriers and transition rates can be estimated from the saddle points and the energy minima along this path. We investigate the dependence of the energy barrier on the strength of the antiferromagnetic coupling and study the reversal in the data bit transition region. Below 1.1 mJ/m2 a two step reversal occurs passing a metastable state. Above 1.1 mJ/m2 this metastable state disappears and the energy barrier is constant for a coupling strength greater than 1.5 mJ/m2.

The hysteresis properties of epitaxial SmCo/Co and SmCo/Fe bilayers are calculated by the solution of the Landau–Lifshitz Gilbert equation. The thin film grain structure is taken into account using appropriate finite element techniques. The J(H) curve shows the typical exchange spring behavior for the bilayer if the soft magnetic layer thickness exceeds 10 nm. However, the reversible rotations of the magnetization for low external field deteriorate the maximum energy density product. Straight B(H) curves are obtained only for a Fe layer thickness of 5 nm. Magnetization reversal starts with the reversible rotation of the soft layer magnetization. Initially, the magnetization rotates in opposite directions in different regions of the film. The reversible rotations penetrate substantially into the hard layer.

The switching process of granular Co nanowires is investigated using the finite element method. The wires have a diameter of 55 nm and a length of 1000 nm. Transmission electron microscopy (TEM) investigations show two different types of hcp-structured grains. For one, the c axis is randomly oriented in a plane perpendicular to the long axis of the wire, and the other has the c axis parallel to the long axis. The numerical results show that finite element micromagnetics can explain the influence of the microstructure in magnetic nanosystems.

The film thickness characteristics and traction behavior, two of the more important elastohydrodynamic lubrication (EHL) properties, of two important classes of synthetic lubricants have been studied. The effect of viscosity index (VI) improvers on these properties has been determined for both hydrogenated polyalphaolefin (PAO) base fluids and chlorotrifluoroethylene oligomer (CTFE) base fluids. A polyalkylmethacrylate (PMM) VI improver was studied in PAO and a copolymer of vinylidine fluoride and chlorotrifluoroethylene was studied in CTFE. The VI improvers demonstrated insignificant improvement in the EHL film thickness of both the PAO and CTFE base fluids as determined by comparing the measured film thickness of the VI-improved fluids to the predicted film thickness based on measured pressure-viscosity characteristics and kinematic viscosities determined at low shear rates. Similarly, the traction behavior of VI-improved PAO and CTFE fluids was nearly equivalent to that of the respective base fluids, d...

According to an estimated mesh shrinkage following hernia repair of up to 40% a current dogma in hernia surgery requires a mesh overlap of 5 cm around the hernia. However, no valid data addressing this problem of mesh shrinkage are available at present.Within the framework of a prospective randomized double-blinded clinical trial, 50 patients were operated on for a ventral abdominal hernia with the open sublay technique using specially prepared radio-opaque polypropylene (PP) meshes. Of the patients 27 received a conventional heavyweight mesh (P group) and 23 a new lightweight mesh construction (NK group). Follow-up for at least 2 years after mesh repair included conventional abdominal x-rays after 7 days, 3 weeks and 4, 12 and 24 months, as well as computed tomography after 7 days and 4 and 12 months. Main criteria were mesh shrinkage, recurrence and complication rates and quality of life comparing groups P and NK.In 46 cases (92%) no mesh shrinkage could be detected and only 4 meshes (8%) showed a moderate shrinkage (1 of 22.2%, 2 of 8% and 1 of 3%) all from the P group. While no hernia recurrences were found, 2 surgical complications occurred with 1 seroma in the P group and 1 hematoma in the NK group. Quality of life showed a linear improvement over time up to the 2 year time point following mesh repair with advantages for the NK group. Pain and mobility scores reached standard values 12 months postoperatively without significant differences between the two groups.In principle PP meshes following an uncomplicated ventral hernia repair do not shrink at all. A moderate shrinkage in isolated cases might occur following heavyweight mesh implantation. Under controlled conditions recurrence as well as complication rates are equal for heavyweight and lightweight PP meshes. Quality of life improves up to 2 years following mesh repair with a trend to a better outcome for lightweight meshes. Pain and mobility scores reached standard values 12 months postoperatively without significant differences between the lightweight and heavyweight meshes.

Analytical formulations for the computation of lubricant film thickness and traction in a high-speed rolling-sliding contact are presented with the objective of investigating the viscoelastic response of the MIL-L-7808-type lubricant Two types of relations are used to model the viscous shear strain rate. In the Type I model, a hyperbolic sine relation is used to model the viscous effect which becomes significant when the shear stress reaches a critical value. The Type II model employs a limiting shear stress, which the lubricant can withstand, and an inverse hyperbolic tangent function is considered to model the viscous behavior. Both models are based on three fundamental properties: lubricant viscosity, shear modulus and a critical shear stress. While the viscosity relations may be obtained by direct measurements, estimates of shear modulus and critical shear stress may be derived by curve-fitting the model predictions to experimental traction data. Presented at the 45th Annual Meeting in Denver, Colorad...

Viscoelastic behavior of the MIL-L-7808-type lubricant is modeled by correlating experimental traction data to rheological models based on lubricant viscosity, shear modulus and a critical or limiting shear stress. The two types of traction models used respectively employ a hyperbolic sine and inverse hyperbolic tangent function between the viscous shear strain rate and shear stress in the lubricant. While the viscosity-pressure-temperature relation is determined from viscosity measurements on a high-pressure viscometer, estimates of shear modulus and critical or limiting shear stress are derived by curve-fitting the model predictions to actual traction data obtained from a rolling-disk traction machine. Presented at the 45th Annual Meeting in Denver, Colorado May 7–10, 1990

The Archaeological Journal, 65, 121-124

The Archaeological Journal, 72, 187-189

Fluorescence cystoscopy of the urinary bladder allows to better identify tumors and altered bladder mucosa (e.g. Carcinoma in situ). Instillation of 5-aminolevulinic acid or hexyl aminolevulinate approx. two hours before transurethral resection leads to metabolism of these compounds in the Häm-biosynthesis and to accumulation of protoporphyrin IX (PPIX). PPIX is an excellent fluorochrom, which lights up red when illuminated by blue light. During transurethral resection all tumors and all suspicious mucosal areas can be completely resected. As a consequence recurrence rate drops and patients need less re-operations and hospitalizations.

Magnetic switching of small particles, thin film elements and magnetic nanowires becomes increasingly important in magnetic storage and magneto electronic devices. Micromagnetic switching events are studied using a hybrid finite element / boundary element method. The space discretization of the Gilbert equation leads to a system of ordinary differential equations. Its numerical integration provides the time evolution of the magnetization under the influence of an external field. Thermal fluctuations may be treated by a random field. The reversal mode drastically depends on the Gilbert damping constant. Decreasing the damping constant from α = 1 to α ≤ 0.1 changes the reversal mode from uniform rotation to inhomogeneous switching. The decrease of the damping leads to the formation of vortices in circular nanodots and to a nucleation process in columnar grains. Elongated Co particles reverse by rotation if the length of the particle is smaller than 25nm. Irreversible switching of longer particles occurs due to the formation of a nucleus of reversed magnetization and successive domain wall motion.

To evaluate a screening protocol for detection of individuals with a higher risk of chronic open angle glaucoma for which a complete glaucoma evaluation is indicated.African Americans over 40 years of age in New Haven, CT. In the screening phase, volunteers filled out a questionnaire and underwent measurements of visual acuity, intraocular pressure (IOP) with a Tono-Pen and visual field with Frequency Doubling Technology. Participants were categorized into "glaucoma likely" or "unlikely," but all were encouraged to follow up with a free complete glaucoma exam, which included applanation tonometry, pachymetry, visual fields with a Humphrey Visual Field Analyzer, gonioscopy, and fundoscopy. Based on the latter exam, patients were categorized into "glaucoma likely" (suspects and confirmed glaucoma) or "unlikely" groups.One hundred eighty-four subjects completed both phases of the study and 76 of 93 patients (82%) who were classified as "glaucoma likely" in the final exam, were also classified as "glaucoma likely" in the screening. Adjusted analysis revealed family history of glaucoma in first degree relatives and screening IOP21 mm Hg to have statistically significant associations with the final impression of "glaucoma likely." A combination of these findings gave an overall sensitivity of 81.7% with a specificity of 55%.In the study population, the combination of an IOP21 mm Hg and history of glaucoma in a first degree relative allowed the identification of a significant percentage of individuals with a higher risk of chronic open angle glaucoma, for which a complete glaucoma examination is indicated.

The aim of this study was to investigate the influence of the manufacturing process on the physicochemical properties of three poorly water soluble compounds (carbamazepine, dipyridamole, and indomethacin) when processed with a polymer (polyvinylpyrrolidone K30 (PVP)) at a 1:2 drug to polymer ratio. Melt extrusion, spray drying, and ball milling techniques were used to prepare glass solutions. Product homogeneity, dissolution, physical stability, and drug/polymer interactions were investigated. Particular attention was paid to solid phase analysis using XRPD, modulated temperature DSC, optical microscopy, and Raman microscopy and the importance of using a combination of techniques was demonstrated. The latter technique when applied to freshly ball milled samples exhibited the presence of drug and polymer rich areas, indicating that complete glass solution formation had not occurred. The three compounds produced products with differing physical stability with indomethacin proving the most physically stable. These differences in physical stability were attributed to hydrogen bonding of drug and polymer. The manufacturing technique did not influence physical stability, but it did affect dissolution. The dissolution of the spray-dried material was generally poor, compared to melt extruded and ball milled products. This was probably due to rapid dissolution of PVP from the small particles of the spray-dried products.

The development of advanced magneto-electronic materials requires a precise understanding of their magnetic behavior. These structures are so small that quantum mechanical effects, like exchange, have to be taken into account. However, they are too large for a pure quantum mechanical description, which would exceed the capabilities of today's ab initio computational models. On this intermediate level, between the macroscopic world and a description with atomic resolution, micromagnetic models provide a useful tool for detailed predictions of the magnetic properties and magnetization processes. The theory of micromagnetism combines Maxwell's equations for the magnetic field with an equation of motion describing the time evolution of the magnetization. The local arrangement of the magnetic moments follows from the complex interaction among intrinsic magnetic properties. The finite-element method is a highly flexible tool to describe magnetization processes, since it is possible to incorporate the physical grain structure and intergranular phases. This chapter discusses recent developments of advanced numerical methods that allow for the first time the modeling and dynamic simulation of an entire media-head system, including sub-grain discretization of the media and a full three-dimensional finite-element mesh of the entire ring head. Moreover, the development of high-performance parallel finite-element micromagnetics packages makes full use of the computational power of novel multiprocessor machines and allows the use of large-scaled complex models.

The potential for high frequency applications of MESFETs made from the wide band gap semiconductors cubic GaN, hexagonal GaN, and 3C-SiC has been investigated by means of device modeling. For comparison, also Si and GaAs MESFETs have been modeled. The influence of nonstationary carrier transport on FET behavior has been estimated using the relaxation time approximation, and taken into account. The three wide band gap semiconductors show considerable potential for application in high frequency MESFETs. Cut-off frequencies exceeding 100 GHz have been predicted for sub-quarter micron gate cubic GaN MESFETs.

We have characterised the stable polymorphic forms of two drug molecules, indomethacin (1) and nifedipine (2) by 13C CPMAS NMR and the resonances have been assigned. The signal for the C-Cl carbon of indomethacin has been studied as a function of applied magnetic field, and the observed bandshapes have been simulated. Variable-temperature 1H relaxation measurements of static samples have revealed a T1rho minimum for indomethacin at 17.8 degrees C. The associated activation energy is 38 kJ mol(-1). The relevant motion is probably an internal rotation and it is suggested that this involves the C-OCH3 group. Since the two drug compounds are potential candidates for formulation in the amorphous state, we have examined quench-cooled melts in detail by variable-temperature 13C and 1H NMR. There is a change in slope for T1H and T1rhoH at the glass transition temperature (Tg) for indomethacin, but this occurs a few degrees below Tg for nifedipine, which is perhaps relevant to the lower real-time stability of the amorphous form for the latter compound. Comparison of relaxation time data for the crystalline and amorphous forms of each compound reveals a greater difference for nifedipine than for indomethacin, which again probably relates to real-time stabilities. Recrystallisation of the two drugs has been followed by proton bandshape measurements at higher temperatures. It is shown that, under the conditions of the experiments, recrystallisation of nifedipine can be detected already at 70 degrees C, whereas this does not occur until 110 degrees C for indomethacin. The effect of crushing the amorphous samples has been studied by 13C NMR; nifedipine recrystallises but indomethacin does not. The results were supported by DSC, powder XRD, FTIR and solution-state NMR measurements.