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To determine whether probiotic prophylaxes reduce the odds of Clostridium difficile infection (CDI) in adults and children.
Individual participant data (IPD) meta-analysis of randomized controlled trials (RCTs), adjusting for risk factors.
We searched 6 databases and 11 grey literature sources from inception to April 2016. We identified 32 RCTs (n=8,713); among them, 18 RCTs provided IPD (n=6,851 participants) comparing probiotic prophylaxis to placebo or no treatment (standard care). One reviewer prepared the IPD, and 2 reviewers extracted data, rated study quality, and graded evidence quality.
Probiotics reduced CDI odds in the unadjusted model (n=6,645; odds ratio [OR] 0.37; 95% confidence interval [CI], 0.25–0.55) and the adjusted model (n=5,074; OR, 0.35; 95% CI, 0.23–0.55). Using 2 or more antibiotics increased the odds of CDI (OR, 2.20; 95% CI, 1.11–4.37), whereas age, sex, hospitalization status, and high-risk antibiotic exposure did not. Adjusted subgroup analyses suggested that, compared to no probiotics, multispecies probiotics were more beneficial than single-species probiotics, as was using probiotics in clinical settings where the CDI risk is ≥5%. Of 18 studies, 14 reported adverse events. In 11 of these 14 studies, the adverse events were retained in the adjusted model. Odds for serious adverse events were similar for both groups in the unadjusted analyses (n=4,990; OR, 1.06; 95% CI, 0.89–1.26) and adjusted analyses (n=4,718; OR, 1.06; 95% CI, 0.89–1.28). Missing outcome data for CDI ranged from 0% to 25.8%. Our analyses were robust to a sensitivity analysis for missingness.
Moderate quality (ie, certainty) evidence suggests that probiotic prophylaxis may be a useful and safe CDI prevention strategy, particularly among participants taking 2 or more antibiotics and in hospital settings where the risk of CDI is ≥5%.
We present an overview of the survey for radio emission from active stars that has been in progress for the last six years using the observatories at Fleurs, Molonglo, Parkes and Tidbinbilla. The role of complementary optical observations at the Anglo-Australian Observatory, Mount Burnett, Mount Stromlo and Siding Spring Observatories and Mount Tamborine are also outlined. We describe the different types of star that have been included in our survey and discuss some of the problems in making the radio observations.
In the United States alone, ∼14,000 children are hospitalised annually with acute heart failure. The science and art of caring for these patients continues to evolve. The International Pediatric Heart Failure Summit of Johns Hopkins All Children’s Heart Institute was held on February 4 and 5, 2015. The 2015 International Pediatric Heart Failure Summit of Johns Hopkins All Children’s Heart Institute was funded through the Andrews/Daicoff Cardiovascular Program Endowment, a philanthropic collaboration between All Children’s Hospital and the Morsani College of Medicine at the University of South Florida (USF). Sponsored by All Children’s Hospital Andrews/Daicoff Cardiovascular Program, the International Pediatric Heart Failure Summit assembled leaders in clinical and scientific disciplines related to paediatric heart failure and created a multi-disciplinary “think-tank”. The purpose of this manuscript is to summarise the lessons from the 2015 International Pediatric Heart Failure Summit of Johns Hopkins All Children’s Heart Institute, to describe the “state of the art” of the treatment of paediatric cardiac failure, and to discuss future directions for research in the domain of paediatric cardiac failure.
Extracellular matrix (ECM)-based materials used for neural interfaces allow for prolonged effective interaction between foreign devices and the neural cells in vivo because they mimic the natural environment. This review will highlight studies that have demonstrated how ECM-based materials can benefit neural interfacing applications as neural electrode coatings, scaffolds, and nanoparticle (NP) coatings. The performance of neural electrodes can degrade from inflammatory response as indicated by the signal obstruction between neurons and electrodes from glial scar formation during prolonged implantation. ECM materials can mitigate an inflammatory response because they are naturally biocompatible and biodegradable. Scaffolds composed from ECM-based materials have the characteristic length scale and biochemical cues that promote directional neural cell growth. ECM-based scaffolds can also be utilized as drug delivery vessels to infuse the neural tissue with neural growth factors and anti-inflammatory cytokines. The NPs currently employed for drug delivery and imaging use various ECM-based coating materials that shield them from the neural cells because many types of NPs are cytotoxic. As demonstrated by these three neural interfacing applications, ECM-based materials are very promising candidates for the development of next-generation neural regeneration and therapeutic devices.
In MCM-D applications, interlayer dielectrics separate and insulate metal conductors to form a three-dimensional interconnection structure. Due to the three-dimensional nature of these structures, the thermal, electrical and mechanical properties of the dielectricmaterials must be known for all orientations in order to correctly design and simulate devices. The most commonly used polymer in microelectronics, polyimide, exists in formulations which have been shown to have a high degree of orientation and exhibit anisotropicproperties.
Micromechanical structures designed for material characterization through analysis of their nonlinear dynamic response are presented. The structures consist of a rigid movable mass supported by beams which are attached to the wafer substrate. The structures are designed so that they are geometrically constrained, which is the source of their nonlinearity. The nonlinearity is shown to be well modeled by Duffing's equation for a stiffening spring and it is this model which is used to fit the test data to the desired mechanical properties, namely Young's modulus, intrinsic stress and damping.
Smart electroceramics, in the form of ferroelectric thin films show great potential for applications in the field of microelectromechanical systems. Ferroelectric thin films will become a key player due to their optical, mechanical, electrical and thermal sensing with actuating capabilities. Recent results on electromechanical transduction in piezoelectric (e.g. PZT), electrostrictive (e.g. PLZT), and antiferroelectricferroelectric phase switching (e.g. PLZSnT) thin films and their potential applications in smart micromechanical systems are discussed. The possibility of three dimensional structures exists in the emerging technology of ferroelectric fibers. Some exciting applications for these films and fibers include microvalves, ultrasonic micromotors, microrobotic actuators and micropumps.
A potentiometric method for the measurement of ultimate strain of thin films is presented. In this method, an electric potential is applied between two electrodes located one on each side of the thin film under investigation. The electrodes are immersed in an electrolytic solution. The thin film acts as an electrical current barrier. To determine the ultimate strain, a controlled load is applied to the film. Cracking of the film causes a sharp rise in the current from an initial small leakage value. The applied load at the onset of cracking is used to calculate the ultimate strain.
we have previously demonstrated the feasibility of the method for thin silicon nitride films deposited on aluminum strips. The method is very sensitive and can detect cracks too small to be observed with a microscope. We discuss extension of the method to the measurement of the ultimate strain of micromachined membranes. The load is applied by pressurizing one side of the membrane. Micromachined structures are used to determine residual stresses.
Measurements of the residual stress in polysilicon films made by Low Pressure Chemical Vapor Deposition (LPCVD) at different deposition pressures and temperatures are reported. The stress behavior of phosphorus (P)-ion implanted/annealed polysilicon films is also reported. Within the temperature range of deposition, 580 °C to 650 °C, the stress vs deposition temperature plot exhibits a transition region in which the stress of the film changes from highly compressive to highly tensile and back to highly compressive as the deposition temperature increases. This behavior was observed in films that were made by the LPCVD process at reduced pressures of 210 and 320 mTORR. At deposition temperatures below 590 °C the deposit is predominantly amorphous, and the film is highly compressive; at temperatures above 610 °C (110) oriented polycrystalline silicon is formed exhibiting high compressive residual stress.
The new technique of scanned force microscopy which enables imaging surface features with sub nanometre resolution has been made possible by the development of highly sensitive, hysteresis free force sensing cantilevers and the availability extremely sharp probing tips. Such cantilevers with integral tips can be micromachined using IC compatible technology, and several processes have been described in literature for their fabrication. These are based on different etching schemes, and require two or more masking stages. A novel process using a single mask is described here for the fabrication of single crystal silicon cantilevers with integral sensing tips. The cantilever thickness can be tailored to provide a range of force constants and resonant frequencies, and the tip profile can be varied from pyramidal to highly cusped. As only a single mask is used in the fabrication, there are no mask alignment errors and precise location of the tip is thereby achieved. This eliminates any twist in the cantilever during scanning which could give rise to distorted imaging. The complete fabrication process and the mask design is described together with SEM photographs of the first batch of devices, which have been evaluated by retrofitting to a commercial atomic force microscope.
The research presented here is an investigation of the effects of phosphorus doping on residual stresses and microstructure in polycrystalline silicon. Undoped polycrystalline silicon films were deposited on phosphosilicate glass layers and annealed at 1050 °C for 5 to 60 minutes. The stress gradient through the film thickness was measured from wafer curvature, and microstructure was examined with cross-sectional TEM. A 20 minute anneal is sufficient for stress relief in initially tensile films and produces a uniform microstructure consisting of 0.1-0.2 µm equi-axed grains.
The piezoresistive effect of materials is used as the basis for many types of microsensors. Polyimide, a material widely used in microelectronic fabrication, may be made to exhibit this effect by addition of small graphite particles to form a composite material. Polyimide / graphite based piezoresistive films have the advantage of being spin-castable, plasma-processable, highly chemically resistant, and thermally stable up to 400 °C in nitrogen atmospheres. In this work, piezoresistive polyimide films are formed by addition of various amounts (loadings) of graphite particles one micron in diameter or less to DuPont PI-2555 polyimide. Thin films of these materials are spin-cast on silicon wafers, and an in-situ load-deflection measurement technique is used to evaluate the following film properties: piezoresistive coefficient as a function of both strain and graphite loading; Young's modulus as a function of graphite loading; and residual film stress as a function of graphite loading. The observed piezoresistive coefficient is a strong function of graphite loading, with good piezoresistive properties exhibited in the loading range of 15–25 wt% graphite.
The selective and alienable deposition of patterned thin film epitaxial GaAs/GaAlAs and InP/InGaAsP devices onto host substrates such as silicon for low cost hybrid integrated micro-opto-electronic systems is reported. Using a combination of semiconductor etch layers and selective etches, the epilayers can be separated from the growth substrate. We use a thin polyimide diaphragm as the transparent transfer medium for these epitaxial materials and devices. Each of these thin film devices or a group of these devices on the polyimide is optically aligned and selectively deposited onto the host substrate. Using this technique, GaAs and InP-based light emitting diodes and optical detectors which are microns thick were grown on lattice matched GaAs and InP substrates, lifted off, aligned and selectively deposited onto a silicon host substrate. The devices were then electrically contacted and tested using standard microelectronic fabrication and testing techniques. This method also enables the manufacturable, sparse distribution of costly photonic devices or the deposition of aligned arrays of devices to fabricate larger arrays. The integration of these light weight devices with microsensors and microactuators will foster micro-opto-electro-mechanical integration.
Experiments have been conducted to study the nonlinear constitutive properties of ferroelectric ceramics for large strain operation applications, where the mechanical behavior of the material dictates the overall electromechanical response of the devices. For this purpose, polarization and strain are measured continuously on a compression cuboid. Severe non-linear and hysteretic behavior is observed in these materials. An empirical formulation has been proposed to model the constitutive laws applicable to this non-linear deformation. Physical mechanism is provided, that is attributed to this constitutive law.
This paper gives an overview of the recent developments in impact, friction, and wear testing of polycrystalline silicon (polysilicon) based micro electromechanical structures. Impact-friction actuated micromechanisms form a new type of actuators. In this type of actuators, lateral resonant structures are retracted by electrostatic comb drives and are propelled forward toward the actuated micromechanism by elastic forces generated by folded beam flexures at frequencies ranging from 10 kHz to 20 kHz. This sequence generates normal impact and tangential friction contact between the two microstructures, raising wear concerns. Two sorts of impact test structures are introduced in this paper, One with a resonant micro impact bumper (MIB) striking a stationary impact wall anchored ofn the substrate. Another is a testing of two MIBs driven to impact each other. Two types of impact actuators are also described, an impact actuated micro angular oscillator (MAO) and a polysilicon micro vibromotor. The vibromotor is a rotor driven by oblique impact on the rim by a converter pointer tip attached to a lateral resonator. Some initial results of impact wear testing as well as static and dynamic friction done by researchers in the field are also described in the paper. Finally, many areas where material scientists can contribute to this field are suggested.