Optical approaches to determine near-surface compositions during epitaxy

To evaluate the demonstration of the pearl necklace sign at magnetic resonance (MR) cholangiopancreatography (MRCP) in patients with proven adenomyomatosis and carcinoma of the gallbladder. MRCP findings and those of a combination of unenhanced and arterial phase computed tomography (CT) and arterial phase MR imaging were retrospectively compared in 29 patients who were pathologically proven to have adenomyomatosis of the gallbladder and in 18 patients with pathologically proven gallbladder carcinoma. Receiver operating characteristic (ROC) analysis was used with a five-point confidence scale. The relative sensitivity, specificity, and accuracy of each imaging modality were also calculated. The pearl necklace sign was defined on MRCP images as small round foci, with the same markedly high signal intensity as bile, within the thickened wall of the gallbladder. The mean area under the ROC curve of MRCP alone and that of the combination of MRCP and arterial phase MR imaging was significantly higher than that of combined CT (unenhanced and arterial phase) and arterial phase MR imaging alone (P <.01). The relative sensitivities in the diagnosis of adenomyomatosis of the gallbladder were 24% for the combined CT, 29% for arterial phase MR imaging, 62% for MRCP, and 57% for the combination of MRCP and arterial phase MR imaging. The mean relative sensitivity, specificity, and accuracy of the pearl necklace sign on MRCP images were 62%, 92%, and 74%, respectively. In eight (28%) of 29 patients with adenomyomatosis of the gallbladder, the pearl necklace sign was not identified by all three readers on the MRCP images. The pearl necklace sign, which indicates the presence of Rokitansky-Aschoff sinuses within the thickened gallbladder wall, was specifically detected at MRCP for adenomyomatosis of the gallbladder.

Appropriate termination of the phototransduction cascade is critical for photoreceptors to achieve high temporal resolution and to prevent excessive Ca(2+)-induced cell toxicity. Using a genetic screen to identify defective photoresponse mutants in Drosophila, we isolated and identified a novel Gα(q) mutant allele, which has defects in both activation and deactivation. We revealed that G(q) modulates the termination of the light response and that metarhodopsin/G(q) interaction affects subsequent arrestin-rhodopsin (Arr2-Rh1) binding, which mediates the deactivation of metarhodopsin. We further showed that the Gα(q) mutant undergoes light-dependent retinal degeneration, which is due to the slow accumulation of stable Arr2-Rh1 complexes. Our study revealed the roles of G(q) in mediating photoresponse termination and in preventing retinal degeneration. This pathway may represent a general rapid feedback regulation of G protein-coupled receptor signaling.

Voltage source inverters (VSIs) with output LCL filters are the key interfaces for today's distributed energy resource. There are mainly two groups of current control methods of a VSI: direct error tracking control with PWM, and closed-loop feedback control. Direct current error control, such as predictive control and hysteresis control, has some drawbacks like system parameter sensitivity, variable switching frequency, etc. On the other hand, the closed-loop feedback control could eliminate many drawbacks of direct error tracking PWM method while with the limited of control bandwidth. Closed-loop current control of a VSI can be of two types namely single-loop and multiple-loop VSI control. According to the feedback currents or number of current sensors used, the closed-loop current control can also be classified into single current sensor and two current sensors feedback system. The stability and dynamic performance of these control schemes differs from each other. However, a thorough understanding of the differences and the reasons behind is not available. This paper presents a comparative analysis of different closed-loop current control method for a VSI with output LCL filters. Effect of LCL filter parameter variation on their stability is investigated. Recently proposed generalized closed-loop control (GCC) platform is used to explain the comparison results. Simulation and experimental results of different VSI control systems are presented.

BackgroundAccurately indentifying heart failure (HF) patients from administrative claims data is useful for both research and quality of care efforts. Yet, there are few comparisons of the various claims data criteria (also known as claims signatures) for identifying HF patients. We compared various HF claim signatures to assess their relative accuracy.MethodsIn this retrospective study, we identified 4174 patients who received care from a large health system in southeast Michigan and who had ≥1 HF encounter between January 1, 2004 and December 31, 2005. Four hundred patients were chosen at random and a detailed chart review was performed to assess which met the Framingham HF criteria. The sample was divided into 300 subjects for derivation and 100 subjects for validation. Sensitivity, specificity,, and area under the curve (AUC) were determined for the various claim signatures. The criteria with the highest AUC were retested in the validation set.ResultsOf the 400 patients sampled, 65% met Framingham HF criteria, and 56% had at least one B-type Natriuretic Peptide (BNP) measurement. There was substantial variation between claims signatures in terms of sensitivity (range 15%-77%) and specificity (range 69%-100%). The best performing criteria in the derivation set was if patients met any one of the following: ≥2 HF encounters, any hospital discharge diagnosis of HF, or a BNP ≥200 pg/ml. These criteria showed a sensitivity of 76%, specificity of 75%, and AUC of 0.754 for meeting the Framingham HF criteria. This claims signature performed similarly in the validation set.ConclusionClaim signatures for HF vary greatly in their relative sensitivity and specificity. These findings may facilitate efforts to identify HF patients for research and quality improvement efforts.

As a part of a validation study, a comparative study of a PCR method and the standard culture-based method NMKL-71, for detection of Salmonella, was performed according to the validation protocol from the Nordic validation organ for validation of alternative microbiological methods (NordVal) on 250 artificially or naturally contaminated animal feed samples. The PCR method is based on culture enrichment in buffered peptone water followed by PCR using the DNA polymerase Tth and an internal amplification control. No significant difference was found between the two methods. The relative accuracy, relative sensitivity and relative specificity were found to be 96.0, 97.3, and 98.8%, respectively. PCR inhibition was observed for rape seed samples. For the acidified feed samples, more Salmonella-positive samples were found with the PCR method compared to the NMKL method. This study focuses on the growing demand for validated diagnostic PCR methods for routine analysis of animal feed and food samples to assure safety in the food production chain.

A comparative study of enzyme-linked fluorescent assay (ELFA)-based methods and real-time polymerase chain reaction (PCR)-based methods using three and two different sample preparation protocols, respectively, and the standard culture-based method EN ISO 6579:2002/Amd1:2007, for the detection of Salmonella spp. in chicken feces, was performed on 20 artificially and 68 naturally contaminated chicken feces. Selectivity, relative specificity, relative accuracy, relative sensitivity, and relative detection level were determined. According to criteria established in the methods comparison study included in EN ISO 16140:2003 for validation of alternative microbiological methods, the ELFA-based methods (V1 and V2) as well as a real-time PCR method (PCR2) were comparable to the reference method for the detection of Salmonella in chicken feces. They provided results in 48 h and presented a high sensitivity (97% for all of them). The three methods showed a relative specificity of 94%, V1 being the method which presented the highest relative accuracy (96%). While detection level for V2 and reference method was between 3 and 13 CFU/25 g, PCR2 method was able to detect down to 3 CFU/25 g. In conclusion, both the real-time PCR and the ELFA-based assays can be used as rapid and user-friendly screening methods for detection of Salmonella spp. in chicken feces.

Florida Hospital, Orlando, Florida, and JLR Medical Group, Maitland, Florida. tdlooke@hotmail.comTo the Editor: As a practicing anesthesiologist with a Ph.D. in control systems engineering, I feel compelled to comment on both the merits and hazards of closed-loop control (CLC) in the operating room, as discussed in the February 2012 article by Liu et al. 1and the accompanying editorial.2CLC is a mature field of engineering with well established standards of analysis, design, and reporting – points missing from Liu et al. 's article and the accompanying editorial. This absence suggests unfamiliarity with the hazards of CLC, which include the risk of introducing instability where none existed before.My main criticism of Liu et al. 's work is that there is no evidence that the appropriate groundwork was done to ensure that the control algorithm was safe (stable) before entering the operating room. Minimizing the hazards of CLC requires a thorough stability analysis before implementation. By way of comparison, it is as important to precede CLC operational testing with computer modeling and simulation studies as it is to precede human drug trials with animal modeling and testing. Testing under extremes of “physiologically challenging conditions such as hypertension, hypotension, morbid obesity, in pediatric patients, or during major surgery such as cardiac surgery or lung transplantation,” as the authors propose for their next clinical trial (see Discussion1), should have been done by simulation before the first clinical trial.Controller design is the key to ultimate success and acceptance of any closed-loop strategy. There are dozens of ways to design closed-loop algorithms. Of all of the available approaches, it is noteworthy that the authors decided to use the PID, or proportional, integral, derivative, approach. The details of how PID controllers work are not important for this point of discussion. The important issue is that the PID approach is the most basic and unsophisticated of algorithms–the first one learned by every CLC engineer in their first undergraduate control course–and is suitable for some simple mechanical, electrical, or hydraulic systems (e.g. , automobile cruise control), but not for complicated, time-variant, nonlinear systems with time delays (e.g. , the surgical patient).Lastly, Liu et al. 's article lacks the necessary engineering detail to evaluate the work. By piecing together comments from the present paper and previous work,3,4it is possible, however, to determine that the controller is in fact not a PID controller. Instead, the authors used empirical methods to develop look-up tables and logic trees to mimic the proportional (P) and derivative (D) terms of a classic PID while ignoring the integral (I) term altogether. The result is that the control algorithm looks more like a crude expert system than a PID controller. An expert system of this type is what would result from a survey of anesthesiologists asked what they would do with propofol and remifentanil infusion rates given particular entropy values.In conclusion, what the authors have done is replace the human anesthesiologist with an ideal, empirically derived, computer anesthesiologist dedicated to the one task of maintaining a set entropy value. For this menial task, the computer wins. For the advancement of closed-loop control design in the operating room, no one wins.Studies using CLC have the potential to significantly impact our specialty and, more importantly, our patients. When considering the publication of CLC articles, the editors of ANESTHESIOLOGY must consider using a control systems engineer in the peer review process. There is precedent for recent and good systems engineering work in the anesthesia literature. I refer to the work of De Smet et al. ,5,6where the authors follow a sound engineering development strategy.Finally, perhaps Crosby and Culley think the future bright if “a dozen operating rooms filled with patients having surgery” are managed by a “lone anesthesiologist … from a distant location.”2In my view, this is an unholy grail. Almost every paper about “closed-loop” anesthesia discusses the similarities of our environment and the cockpit. Without doubt there is one way they are exactly alike: Patients and passengers would recoil if they were to learn that their anesthesiologist or pilot would be in abstentia. The ideal goal of control systems engineering in the operating room is not the elimination of anesthesia staff, but the ability to prescribe an effect rather than a dose. Imagine a future where we say “set end-tidal carbon dioxide to 36, set mean arterial pressure to 80, set heart rate to 70, set pain response to 0, set awareness to 45,” and then watch as safe, stable, robust, and reliable control algorithms adjust all fluids and anesthetics at once to achieve these results. This is a bright future, indeed.

Galvanizing is the process of applying a protective zinc or zinc alloy coating to steel or iron which acts as a sacrificial anode to protect the underlying steel or iron. These coatings are mainly used in the automotive and construction industry where corrosive environments will be encountered. There has been a drive to improve the performance of galvanised coatings through alloy additions, initially Al (5 – 55 wt%) and more recently through the development of Zn - Al - Mg coatings. Here, Al and Mg are added as minority additions (typically 1 - 3 wt %) to improve corrosion resistance allowing thinner coatings to be used thus saving material, weight and cost. The assessment of the corrosion performance of such coatings is often evaluated through standardised tests. An industry standard test known as Prohesion or ASTM G85 Annex A5 is carried out on metallic coatings as it is thought to better represent long-term natural exposure than a regular salt spray test. The Prohesion test is a cyclic accelerated corrosion test using an electrolyte of 0.4% Ammonia sulphate and 0.05% sodium chloride (NaCl).This investigation aims to determine the effects on the corrosion performance of zinc-aluminium alloys and zinc-aluminium-magnesium alloys of varying compositions immersed in Prohesion solution. Previous work on this topic suggests that magnesium containing alloys were particularly susceptible to accelerated corrosion in Prohesion solution. Here, several zinc based alloys were immersed in Prohesion solution as well as a control 0.45% sodium chloride solution and subjected to electrochemical testing. The electrochemical techniques used to test said substrates are linear polarisation resistance (LPR), scanning vibrating electrode technique (SVET) and time-lapse optical microscopy (TLM) all for 24 hours. The alloys that underwent testing are shown in Table 1. Table 1: Table showing the composition of substrates used.Sample number Composition 1 Zn-<0.2wt%Al 2 Zn-5wt%Al 3 Zn-55wt%Al 4 Zn-1.2wt%Al-Zn1.2wt%Mg 5 Zn-3.5wt%Al-3wt%Mg 6 Zn-6wt%Al-3wt%Mg The results from the TLM showed differences in the corrosion mechanism that is dependent on the alloy composition and electrolyte. Generally, all substrates immersed in the control 0.45% NaCl showed localised corrosion with distinct anodes developing surrounded by a ring of corrosion product and white rust is observed on the surface of the substrate. The initial site of anodic attack in the microstructure was dependent on the alloy composition. However, when immersed in the Prohesion solution significant differences were observed dependent on the alloy composition. For Zn-Al-Mg coatings rapid attack of zinc-magnesium phases was observed especially in the eutectic regions followed by aggressive attack of the entire exposed surface of the alloy within 6 hours. Additionally, no corrosion product rings formed. For Zn-Al alloy coatings, the zinc phases were preferentially attacked with the aluminium containing phases appearing to be resistant to corrosion during the duration of the tests. No white rust was seen on the surface of the substrates and instead a dark surface/corrosion product film was observed. The corrosion rate from the LPR data measured at hourly intervals over 24 hours increases when substrates are immersed in Prohesion solution compared to NaCl, with the most noticeable increase seen when there are zinc-magnesium phases present within the alloy. The largest increase in corrosion rate mm per year (mmpy) was seen in sample 5 with it increasing from 0.15 mmpy after 24 hours in the control solution to 0.55 mmpy in the Prohesion solution after 24 hours. The same is observed with the SVET results showing that the ammonium ions are having a significant damaging effect on the Zn-Al-Mg metallic coatings. The proposed corrosion mechanism for Zn-Al-Mg alloy coatings in Prohesion solution is preferential dissolution of MgZn2 in eutectic phases due to reactivity of Mg producing Mg(OH)2 which is a highly basic hydroxide. Due to the basic nature of Mg(OH)2, Ammonium (NH4 +) cations react with Mg(OH)2 producing Mg2+ and Ammonia (NH3).Mg(OH)2+2NH4 +=Mg2++2NH3+2H2OZn(OH)2 does not undergo this reaction to the same extent as it hydrolyses in water (producing H+) therefore is not basic enough to support much NH3 production. Neutral NH3 reacts with metallic Zn or Zn2+ compounds to produce highly soluble zinc (II) tetra-ammine complex cations. Therefore, the protective Zn and Mg compounds forming at the metal surface will dissolve and the surface will become activated. This is demonstrated by the lack of white rust shown from samples immersed in the Prohesion solution. Al phases are resistant to NH3 hence the better performance of Zn-Al coatings and the preferential attack of the Zn in the Zn-Al timelapse microscopy.

In order to improve the efficiency of underground mining and tunneling operations and to realize automatic drilling, it is necessary to develop the automation system for large drill jumbos. This work focuses on one such mining drill jumbo which is actually a redundant robotic manipulator with eight degrees of freedom, because it has six revolute joints and two prismatic joints. To realize the autonomous drilling operation, algorithms are proposed to calculate the desired pose of the end-effector and to solve the inverse kinematics of the drill jumbo, which is one of the key issues for developing the automation system. After that, a control strategy is proposed to independently control the eight joint variables using PID feedback control approaches. The simulation model is developed in Simulink. As the closed-loop controllers corresponding to all joints are local and independent of each other, the whole system is not a closed-loop feedback control. In order to estimate the possible maximal pose error, the analysis of the pose error caused by the errors of the joint variables is conducted. The results are satisfactory for mining applications and the developed automation system is being applied in the drill jumbos built by Mining Technologies International Inc.

A high-precision variable-thrust control method based on real-time measurement of pintle displacement and closed-loop feedback control is proposed to solve the technical problems of deep throttling variable-thrust regulation and control of pintle liquid rocket engines (LRE). By optimizing the system structure and control parameters, the closed-loop control of displacement with high precision and a fast response under a wide range of variable thrust can be realized, and thus the large-range, fast-response, and high-precision control of the chamber pressure, equivalent to thrust, can be indirectly realized. The chamber pressure response time is not more than 0.3 s, the overshoot is not more than ±3%, and the pulsation amplitude is not more than ±5%, which can meet the technical requirements of the large-range thrust adjustment and control of variable-thrust LRE of reusable launch rockets. The proposed variable-thrust LRE thrust control system is simple, reliable, and easy to use and maintain, which solves the problem of the large range, high precision, and fast response of thrust adjustment and control. The proposed system can provide important technical support for carrier rocket recycling and launch cost reduction. This is the first time a closed-loop control method of displacement of an integrated gas generator/flow regulator to achieve a 5:1 large-range continuous-variable-thrust control for the LRE of a reusable launch rocket has been proposed.

Stochastic dynamic programming has been. extensively used in the optimization of long term hydrothermal scheduling problems due to its ability to cope with the nonlinear and stochastic characteristics of such problems, and the fact that it provides a closed-loop feedback control policy. Its computational requirements, however, tend to be heavy even for systems with a small number of hydroplants, requiring some sort of modeling manipulation in order to be able to handle real systems. An alternative to closed-loop optimization is an approach that combines a deterministic optimization model with an inflow forecasting model in a partial open-loop feedback control framework. At each stage in this control policy, a forecast of the inflows during the period of planning is made, and an operational decision for the following stage is obtained by a deterministic optimization model. The present paper compares such closed-loop and partial open-loop feedback control policies in long term hydrothermal scheduling, using a single hydroplant system as a case study to focus the comparison on the feedback control performance. The comparison is made by simulation using data from historical and synthetical inflow sequences in the consideration of three different Brazilian hydroplants located in different river basins. Results have demonstrated that the performance of the partial open-loop feedback control policy is similar to that of the closed-loop control policy, and is even superior in dry streamflow periods.

Combination of Recombinase Polymerase Amplification with SYBR Green I for naked-eye, same-day detection of Escherichia coli O157:H7 in ground meat

Particle-induced X-ray emission (PIXE) has been applied to the analysis of inorganic materials to determine some elements with Z<27: Na, Mg, Al, Si, K, Ca, Ti, Mn and Fe, in thick-target analysis. A PIXE method has been developed for the analysis of geological materials, ceramics and pottery. Work has been carried out with an ion beam analytical system, using a low particle beam energy. Relative sensitivity, detection limits, reproducibility and accuracy of the method were calculated based on the analysis of geological standard materials (river sediments, argillaceous limestone, basalt, diorite and granite). Analysis using PIXE offers a number of advantages, such as short analysis time, multi-elemental and non-destructive determinations, and the results are similar to those obtained with other instrumental techniques of analysis.

Using the helix-coil transitions of alanine pentapeptide as an illustrative example, we demonstrate the use of diffusion maps in the analysis of molecular dynamics simulation trajectories. Diffusion maps and other nonlinear data-mining techniques provide powerful tools to visualize the distribution of structures in conformation space. The resulting low-dimensional representations help in partitioning conformation space, and in constructing Markov state models that capture the conformational dynamics. In an initial step, we use diffusion maps to reduce the dimensionality of the conformational dynamics of Ala5. The resulting pretreated data are then used in a clustering step. The identified clusters show excellent overlap with clusters obtained previously by using the backbone dihedral angles as input, with small--but nontrivial--differences reflecting torsional degrees of freedom ignored in the earlier approach. We then construct a Markov state model describing the conformational dynamics in terms of a discrete-time random walk between the clusters. We show that by combining fuzzy C-means clustering with a transition-based assignment of states, we can construct robust Markov state models. This state-assignment procedure suppresses short-time memory effects that result from the non-Markovianity of the dynamics projected onto the space of clusters. In a comparison with previous work, we demonstrate how manifold learning techniques may complement and enhance informed intuition commonly used to construct reduced descriptions of the dynamics in molecular conformation space.

Previous results on proving confluence for Constraint Handling Rules are extended in two ways in order to allow a larger and more realistic class of CHR programs to be considered confluent. Firstly, we introduce the relaxed notion of confluence modulo equivalence into the context of CHR: while confluence for a terminating program means that all alternative derivations for a query lead to the exact same final state, confluence modulo equivalence only requires the final states to be equivalent with respect to an equivalence relation tailored for the given program. Secondly, we allow non-logical built-in predicates such as var/1 and incomplete ones such as is/2, that are ignored in previous work on confluence. To this end, a new operational semantics for CHR is developed which includes such predicates. In addition, this semantics differs from earlier approaches by its simplicity without loss of generality, and it may also be recommended for future studies of CHR. For the purely logical subset of CHR, proofs can be expressed in first-order logic, that we show is not sufficient in the present case. We have introduced a formal meta-language that allows reasoning about abstract states and derivations with meta-level restrictions that reflect the non-logical and incomplete predicates. This language represents subproofs as diagrams, which facilitates a systematic enumeration of proof cases, pointing forward to a mechanical support for such proofs. The Project is supported by The DanishCouncil for IndependentResearch, Natural Sciences, Grant No. DFF4181-00442. The second author’s contribution received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under Grant Agreement No. 318337, ENTRA—Whole-Systems Energy Transparency.