APT System Research Articles

Testing plasmid stability of Escherichia coli using the Continuously Operated Shaken BIOreactor System.

Plasmids are common vectors to genetically manipulate Escherichia coli or other microorganisms. They are easy to use and considerable experience has accumulated on their application in heterologous protein production. However, plasmids can be lost during cell growth, if no selection pressure like, e.g., antibiotics is used, hampering the production of the desired protein and endangering the economic success of a biotechnological production process. Thus, in this study the Continuously Operated Shaken BIOreactor System (COSBIOS) is applied as a tool for fast parallel testing of strain stability and operation conditions and to evaluate measures to counter such plasmid loss. In specific, by applying various ampicillin concentrations, the lowest effective ampicillin dosage is investigated to secure plasmid stability while lowering adverse ecological effects. A significant difference was found in the growth rates of plasmid-bearing and plasmid-free cells. The undesired plasmid-free cells grew 30% faster than the desired plasmid-bearing cells. During the testing of plasmid stability without antibiotics, the population fraction of plasmid-bearing cells rapidly decreased in continuous culture to zero within the first 48 h. An initial single dosage of ampicillin did not prevent plasmid loss. By contrast, a continuous application of a low dosage of 10 µg/mL ampicillin in the feed medium maintained plasmid stability in the culture. Consequently, the COSBIOS is an apt reactor system for measuring plasmid stability and evaluating methods to enhance this stability. Hence, decreased production of heterologous protein can be prevented. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1418-1425, 2016.

The complete chloroplast genome of parasitic flowering plant Monotropa hypopitys: extensive gene losses and size reduction

Plastid genomes of parasitic plants represent apt systems, in which the effects of relaxed selective pressure on photosynthetic function are studied. The complete chloroplast genome sequence of nonphotosynthetic mycoheterotrophic plant Monotropa hypopitys was determined. With only 19 protein-coding, four rRNA and 17 tRNA genes in 34 800 bp long genome, it is one of the most reduced plastid genomes characterized until now. Monotropa chloroplast genome lacks all genes encoding photosynthetic functions and RNA polymerase subunits but retains most of the ribosomal protein genes and housekeeping genes infA and matK. Monotropa represents the late stages of chloroplast genome decay following the transition to heterotrophy.

Assessing the risk: Scoring systems for outcome prediction in emergency laparotomies.

Emergency laparotomy is the commonest emergency surgical procedure in most hospitals and includes over 400 diverse surgical procedures. Despite the evolution of medicine and surgical practices, the mortality in patients needing emergency laparotomy remains abnormally high. Although surgical risk assessment first started with the ASA Physical Status score in 1941, efforts to find an ideal scoring system that accurately estimates the risk of mortality, continues till today. While many scoring systems have been developed, no single scoring system has been validated across multiple centers and geographical locations. While some scoring systems can predict the risk merely based upon preoperative findings and parameters, some rely on intra-operative assessment and histopathology reports to accurately stratify the risk of mortality. Although most scoring systems can potentially be used to compare risk-adjusted mortality across hospitals and amongst surgeons, only those which are based on preoperative findings can be used for risk prognostication and identify high-risk patients before surgery for an aggressive treatment. The recognition of the fact, that in the absence of outcome data in these patients, it would be impossible to evaluate the impact of quality improvement initiatives on risk-adjusted mortality, hospital groups and surgical societies have got together and started to pool data and analyze it. Appropriate scoring systems for emergency laparotomies would help in risk prognostication, risk-adjusted audit and assess the impact of quality improvement initiative in patient care across hospitals. Large multi-centric studies across varied geographic locations and surgical practices need to assess and validate the ideal and most apt scoring system for emergency laparotomies. While APACHE-II and P-POSSUM continue to be the most commonly used scoring system in emergency laparotomies,studies need to compare them in their ability to predict mortality and explore if either has a higher sensitivity and specificity than the other.

Gold nanoparticle–DNA aptamer composites as a universal carrier for in vivo delivery of biologically functional proteins

Although the delivery of biologically functional protein(s) into mammalian cells could be of tremendous value to biomedical research, the development of such technology has been hindered by the lack of a safe and effective delivery method. Here, we present a simple, efficient, and versatile gold nanoparticle–DNA aptamer conjugate (AuNP–Apt)-based system, with nanoblock-like properties, that allows any recombinant protein to be loaded without additional modifications and delivered into mammalian living systems. AuNP–Apt-based protein delivery system was able to deliver various proteins into variety of cell types in vitro without showing cytotoxicity. This AuNP–Apt system was also effective for the local and systemic targeted delivery of proteins in vivo. A local injection of the AuNP–Apt loaded with the apoptosis-inducing BIM protein efficiently inhibited the growth of xenograft tumors in mice. Furthermore, an intravenous injection of AuNP–Apt loaded with both epidermal growth factor (EGF) and BIM resulted in the targeted delivery of BIM into a xenograft tumor derived from EGF receptor-overexpressing cancer cells with no detectable systemic toxicity. Our findings show that this system can serve as an innovative platform for the development of protein-based biomedical applications.

Design of 2_DOF Simulation Platform for the Testing of Airborne Laser Communication APT System

Lightweight, flexible motion simulation is the demand of airborne laser communication optical transceive when apply to outside test. A new parallel 2_DOF platform that has the function of azimuth and pitching is put forword based on the analysis of airplane position-pose changes affect the performance airborne laster communication APT system, and the kinematics model is established by using closed-loop vector method. Kinematics model is right through the comparison of mathematical model and simulation results of ADAMS, which provides the reference and basis for the design of control system.

Navigating actions through the rodent parietal cortex.

The posterior parietal cortex (PPC) participates in a manifold of cognitive functions, including visual attention, working memory, spatial processing, and movement planning. Given the vast interconnectivity of PPC with sensory and motor areas, it is not surprising that neuronal recordings show that PPC often encodes mixtures of spatial information as well as the movements required to reach a goal. Recent work sought to discern the relative strength of spatial vs. motor signaling in PPC by recording single unit activity in PPC of freely behaving rats during selective changes in either the spatial layout of the local environment or in the pattern of locomotor behaviors executed during navigational tasks. The results revealed unequivocally a predominant sensitivity of PPC neurons to locomotor action structure, with subsets of cells even encoding upcoming movements more than 1 s in advance. In light of these and other recent findings in the field, I propose that one of the key contributions of PPC to navigation is the synthesis of goal-directed behavioral sequences, and that the rodent PPC may serve as an apt system to investigate cellular mechanisms for spatial motor planning as traditionally studied in humans and monkeys.

General model on polarization compensation in satellite-to-ground quantum communication

A general model in satellite-to-ground quantum communication is proposed by investigating the effect of a laser acquisition, pointing, and tracking (APT) system on the polarization state of single photons. The eccentricity of the general model ranges from 0 to 1, which means that a circular orbit can be introduced reasonably. Moreover, the geocentric-equatorial coordinate system, which can utilize the two-line elements, is used in the general model. Two kinds of simulations are performed, and we found that the rotations of polarization state are obviously influenced by the APT system. Our model could be applied in a realistic satellite-to-ground quantum communication system.

Early Origins of Adult Disease: Approaches for Investigating the Programmable Epigenome in Humans, Nonhuman Primates, and Rodents

According to the developmental origins of health and disease hypothesis, in utero experiences reprogram an individual for immediate adaptation to gestational perturbations, with the sequelae of later-in-life risk of metabolic disease. An altered gestational milieu with resultant adult metabolic disease has been observed in instances of both in utero constraint (e.g., from famine or uteroplacental insufficiency) and overt caloric abundance (e.g., from a maternal high-fat, caloric-dense diet). The commonality of the adult metabolic phenotype begs the question of how diverse in utero experiences (i.e., reprogramming events) converge on common metabolic pathways and how the memory of these events is maintained across the lifespan. We and others have investigated the molecular mechanisms underlying fetal programming and observed that epigenetic modifications to the fetal and placental epigenome accompany these reprogramming events. Based on several lines of emerging data in human and nonhuman primates, it is now felt that modified epigenetic signature--and the histone code in particular--underlies alterations in postnatal gene expression and metabolic pathways central to accurate functioning and maintenance of health. Because of the tissue lineage specificity of many of these modifications, nonhuman primates serve as an apt model system for the capacity to recapitulate human gene expression and regulation during development. This review summarizes recent epigenetic advances using rodent and primate (both human and nonhuman) models during in utero development and contributing to adult diseases later in life.

The plastid genome of the mycoheterotrophicCorallorhiza striata(Orchidaceae) is in the relatively early stages of degradation

Plastid genomes of nonphotosynthetic, mycoheterotrophic plants represent apt systems in which to study effects of relaxed evolutionary constraints. The few mycoheterotrophic angiosperm plastomes sequenced to date display drastic patterns of degradation/reduction relative to those of photosynthetic relatives. The goal of this study was to focus on a mycoheterotrophic orchid hypothesized to be in the "early" stages of plastome degradation, to provide perspective on this process. Short-read sequencing was used to generate a complete plastome sequence for Corallorhiza striata var. vreelandii, a mycoheterotrophic orchid, to investigate the extent of plastome degradation. Patterns of nonsynonymous/synonymous mutations were also assessed, and comparisons were made between Corallorhiza and other heterotrophic plant lineages. Corallorhiza yielded a plastome of 137505 bp, with several photosynthesis-related genes either lost or pseudogenized. Members of all major photosynthesis complexes, except ATP-synthase genes, were affected. "Housekeeping" genes were intact, despite the loss of a single tRNA. Intact photosynthesis genes (excluding atp genes) together displayed elevated nonsynonymous changes, while housekeeping genes did not. The Corallorhiza plastome is not drastically reduced in overall size (∼6% reduction relative to that of photosynthetic Oncidium), but displays a pattern congruent with a loss of photosynthetic function. Comparing Corallorhiza with other heterotrophs allows some emergent evolutionary patterns to be inferred, but these remain as hypotheses to be tested, especially at lower taxonomic levels, and in lineages illustrating transitions from autotrophy to heterotrophy. The independent, unique processes of plastome modification among mycoheterotrophic lineages illustrate the urgency of their conservation.

Perspective: Matching, Mate Choice, and Speciation

Matching was developed in the 1960s to match such entities as residents and hospitals, colleges and students, or employers and employees. This approach is based on "preference lists," whereby each participant ranks potential partners according to his/her preferences and tries to match with the highest-ranking partner available. Here, we discuss the implications of matching for the study of mate choice and speciation. Matching differs from classic approaches in several respects, most notably because under this theoretical framework, the formation of mating pairs is context-dependant (i.e., it depends on the configuration of pairings in the entire population), because the stability of mating pairs is considered explicitly, and because mate choice is mutual. The use of matching to study mate choice and speciation is not merely a theoretical curiosity; its application can generate counter-intuitive predictions and lead to conclusions that differ fundamentally from classic theories about sexual selection and speciation. For example, it predicts that when mate choice is mutual and the stability of mating pairs is critical for successful reproduction, sympatric speciation is a robust evolutionary outcome. Yet the application of matching to the study of mate choice and speciation has been largely dominated by theoretical studies. We present the hamlets, a group of brightly colored Caribbean coral reef fishes in the genus Hypoplectrus (Serranidae), as a particularly apt system to test empirically specific predictions generated by the application of matching to mate choice and speciation.

Influence Analysis of CCD Miss-Distance and Corresponding Research of τ Compensatory Technology Based on Finite Memory

A series of time lag taches result in miss-distance lag in the coarse tracking system of APT system, which will greatly influence the tracking precision of the whole FSO communication system. In order to provide theory basis for determining the sampling frequency and components with time lag character, the influence on systems stability resulted from phase margin loss caused by miss-distance lag is analyzed in detail. To eliminate the influence caused by miss-distance lag, finite memory based τ Compensatory Technology is put forward, which has characteristics of simple program realization, low CPU overhead and high precision, experiment result shows that miss-distance lag based on τ Compensatory Technology is feasible and effective to practical APT system.

Experimental and molecular dynamics studies on corrosion inhibition of mild steel by 2-amino-5-phenyl-1,3,4-thiadiazole

The corrosion inhibition of mild steel in 0.5 M H 2SO 4 and 1.0 M HCl by 2-amino-5-phenyl-1,3,4-thiadiazole (APT) has been studied using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. The results show that the inhibition efficiency increases with the increase of APT concentration in both acids, and the higher inhibition efficiency is obtained in 0.5 M H 2SO 4. The adsorption of APT molecules on the steel surface obeys Langmuir adsorption isotherm in both acids, and occurs spontaneously. The molecular dynamics method has also been used to simulate the adsorption of ATP molecule and solvent ions on the iron surface. The results show that with the adsorption of sulfate ions the Fe + anion + APT system has the higher negative interaction energy comparing to the case of the adsorption of chloride ions.

A fresh approach to automatic navigation of AVHRR images

We describe a simple but very accurate method of navigating AVHRR images. We do not use ground control points, and our orbital calculations are performed by the SGP4 system, which reports satellite positions and heights. We also show how to modify our procedure for the APT system. Our navigation is near-real-time: within thirty minutes of first acquisition of the satellite signal we produce a geo-located HRPT image in an export format of the user's choice. This is the start of a programme of work aiming at the automatic processing of large area scenes.

Market liquidity and depth on two different electronic trading systems: A comparison of Bund futures trading on the APT and DTB

This paper investigates the liquidity of two different electronic trading systems – the APT system at LIFFE and the DTB system. First we describe the different characteristics of the trading systems and give potential reasons as to why they might differ in liquidity. Second we investigate empirically the liquidity provided by the two trading system. The comparison is especially interesting because the Bund Futures instruments traded are identical and the markets are open simultaneously. The intra-day data used in the study is from August 1997 to February 1998. The results show that the APT has smaller spread but the DTB is slightly deeper.

Cold pain prolongs gastric emptying of liquid but not solid meal: an electrical impedance tomography (EIT) study.

Stressful stimuli are reported to affect gastric emptying. However, methods for measuring gastric emptying are, in themselves, stressful. Electrical impedance tomography (EIT) is a method for measuring gastric emptying noninvasively. We used EIT to measure gastric emptying of liquid and solid meals to determine the effect of cold pain stress on gastric emptying. EIT (DAS-01P APT system; University of Sheffield, UK) was carried out in six healthy women (age, 21.6 +/- 0.4 [mean +/- SD] years) who had ingested a liquid (potage, 263 g; 139 kcal) or solid (beef patty, 205 g; 435 kcal) test meal. Cold pain stimuli consisted of repeated immersions of the subject's non-dominant hand into ice water (4 degrees C) for 1 min, with a 15-s recovery period between immersions, for a total of 20 min. For the control stimulus, water at 37 degrees C was used. The cold pain stimulus was applied immediately after the ingestion of a test meal. All studies were carried out randomly in each subject at intervals of more than 1 week. With cold pain, the half emptying time of the liquid meal was significantly greater than that with the control stimulus (47.6 +/- 26.1 min vs 28.1 +/- 10.8 min, P < 0.05). For the solid meal, the half emptying time did not differ between stimuli (101.9 +/- 44.8 min with cold pain vs 92.6 +/- 30.5 min with control stimulus). There were no significant differences in lag time between the liquid and solid meals. Cold pain stress delayed gastric emptying of liquid but not solid meals.

Water Chemistry Control for the Target/Blanket Region of the Accelerator Production of Tritium

High-energy particle interactions in the various components of the target/blanket region of the Accelerator Production of Tritium lead to heat generation and deposition. Heavy-water and light-water systems are used to cool the target/blanket system and associated equipment. Structural materials include Inconel alloy 718, aluminum-clad lead rods, aluminum tubes containing helium-3 and tritium gas, and stainless steel components. Proper coolant chemistry is required to maximize neutron production, minimize corrosion of components, and minimize activity buildup. Corrosion-related phenomena and development of coolant and moderator corrosion control for both power and defense fission reactors has been studied extensively over the past 50 years. Less is known, however, about cooling systems for accelerators where a variety of transient chemical species and spallation products may be formed. The following provides a discussion on the issues that need to be addressed for proper water chemistry control for the APT system.

Monitoring perioperative changes in distribution of pulmonary ventilation by functional electrical impedance tomography.

Electrical impedance tomography (EIT) is a noninvasive technique providing cross-sectional images of the thorax. We have tested an extended evaluation procedure, the functional EIT (f-EIT), to identify the local shifts of ventilation known to occur during the transition between spontaneous, controlled and assisted ventilation modes. Ten patients scheduled for elective laparotomy were studied in the surgical ward, operating theatre and ICU during spontaneous and different modes of mechanical ventilation. Sixteen ECG electrodes were placed on the circumference of the thorax and connected with an EIT device (APT System Mark I, IBEES, Sheffield, UK). Measurements lasting 180 s were performed and f-EIT images of regional ventilation computed. The geometrical centre of ventilation was determined to quantify the regional distribution of lung ventilation during individual modes of ventilation. F-EIT confirmed the differences in the distribution of ventilation associated with various modes of artificial ventilation. Accentuated ventilation of the dependent lung regions was observed during spontaneous breathing, whereas a shift of the centre of ventilation to the nondependent regions was found during controlled ventilation. In the course of assisted ventilation a continuous displacement of the centre of ventilation back towards the dependent lung regions, consistent with an increased proportion of spontaneous breathing, was detected. Unassisted spontaneous breathing after weaning from mechanical ventilation resulted in a similar ventilation distribution as during tidal breathing prior to surgery. F-EIT determined the redistribution of lung ventilation during different modes of mechanical ventilation. We expect that f-EIT will become a useful noninvasive bedside monitoring technique for imaging regional ventilation in pulmonary diseased patients during mechanical ventilation.

Application of antenna arrays to mobile communications. II. Beam-forming and direction-of-arrival considerations

Array processing involves manipulation of signals induced on various antenna elements. Its capabilities of steering nulls to reduce cochannel interferences and pointing independent beams toward various mobiles, as well as its ability to provide estimates of directions of radiating sources, make it attractive to a mobile communications system designer. Array processing is expected to play an important role in fulfilling the increased demands of various mobile communications services. Part I of this paper showed how an array could be utilized in different configurations to improve the performance of mobile communications systems, with references to various studies where feasibility of apt array system for mobile communications is considered. This paper provides a comprehensive and detailed treatment of different beam-forming schemes, adaptive algorithms to adjust the required weighting on antennas, direction-of-arrival estimation methods-including their performance comparison-and effects of errors on the performance of an array system, as well as schemes to alleviate them. This paper brings together almost all aspects of array signal processing.

Changes in the thoracic impedance distribution under different ventilatory conditions

The present study was performed with the aim of checking the suitability of EIT in imaging regional thoracic impedance variations during lung ventilation under predefined conditions and to compare EIT with established reference techniques. A new technique of functional EIT imaging designed to visualize physiologically relevant information from the sequentially registered series of thoracic impedance distributions was introduced. Experiments were performed on five spontaneously breathing healthy subjects and on 12 anaesthetized supine pigs. 16 electrodes were placed around the thorax and consecutive transthoracic impedance distributions were measured at a rate of 1 Hz (Sheffield APT system mark I, IBEES, Sheffield, UK). Several voluntary breathing manoeuvres were performed in human subjects and the tracings of local impedance were compared with standard spirometry. In animal experiments EIT was applied during artificial ventilation at different ventilation rates and during stepwise passive emptying and filling of either one or both lungs while the respiratory muscles were relaxed. Further, selective blockade of lung regions resulting in regionally reduced ventilation was performed and the capability of EIT to follow and differentiate local ventilatory disturbances was checked by reference techniques (X-ray and staining methods). The experiments revealed an overall agreement between the spirometric and impedance data in all breathing patterns performed. A linear relationship between changes of the air content of the lungs and the regional thoracic impedance was shown (intraindividual correlation coefficient range, 0.986-0.999; n=12 animals). The functional images of the impedance distribution across the thorax reproduced adequately the typical anatomical characteristics of the pig and the human thorax. The spatial resolution of EIT functional images was sufficient to differentiate lung areas corresponding to approximately 20 ml tissue volume. EIT with the additional evaluation procedure of functional imaging was shown to be a suitable and reliable method of imaging different ventilatory conditions with the potential to become a useful tool for monitoring respiratory function.

MACHINE LEARNING GOES TO THE BANK

This paper describes how the APT system has been applied to loan analysis to generalized and refine the knowledge previously used by an expert system, in order to increase the efficiency and the compactness of the decision rule base. The decision to lend money to industrial companies is a complex and risky activity for financial institutions. They need much expertise to deal with the large amount of information that has to be considered for this process, and the analysis must be carefully done in order to avoid misjudgments that would result in severe losses of unrecoverable credit. An expert system named SPAC had been developed to deal with this task without fulfilling the user's expectations. This paper presents the drawbacks of SPAC's approach and how APT, an integrated machine learning system, has been used to acquire and refine domain knowledge and general decision rules from basic descriptions of cases provided by SPAC. The learning methodology is detailed, and a complete example of a learning session with APT is given. The final results are then compared with those obtained with SPAC