Synthetic View Research Articles

Ongoing Pursuit of Diterpenoid Alkaloids: A Synthetic View

AbstractThe incorporation of nitrogen atoms into policyclic diterpenes has led to one of the most fascinating group of natural products with cage‐like structures: diterpenoid alkaloids. Their singular architectural features and significant bioactivities made them highly pursued targets amongst the synthetic community over decades. A total of seven types of diterpenoid alkaloid molecules have been synthesized thus far, and the research in this area experienced a new climax in the past five years. With a brief overview and summary of the historic achievements, this Focus Review particularly covers the recent, post‐2010 advances in the field of diterpenoid alkaloid synthesis, highlighting the utilization of innovative synthetic methods and strategies. Despite numerous achievements, there are still a number of such alkaloids with different and unique structural types waiting to be accomplished, implying that the pursuit is far from ending.

Supercritical fractionation of Agathosma (buchu) essential oil. Part I: Measurement of binary phase equilibria

The value of essential oils can be improved by removing the potentially unstable compounds, such as monoterpene hydrocarbons (MT), in a process known as deterpenation. In order to determine the feasibility of deterpenation using supercritical CO2, the phase behaviour of the pure components in CO2 must be known. Phase equilibria data of most components found in buchu essential oil in supercritical CO2 are not available in the literature. In this study, the phase equilibria of binary systems pulegone+CO2, diosphenol+CO2, terpinen-4-ol+CO2 and limonene+CO2 were measured between 308K and 358K, and at solute mass fractions between 0.0147 and 0.638, using a static synthetic view cell. The data were modelled using Chrastil's equation and separation factors determined. Oxygenated terpenes (OT) are significantly less soluble than MT, especially at the higher temperatures, indicating the possibility of separation.

Organellar non-coding RNAs: emerging regulation mechanisms.

Originally focused on the nuclear and cytosolic compartments, the concept of regulation driven by non-coding RNAs (ncRNAs) is extending to mitochondria and chloroplasts. These organelles have distinct genetic systems that need coordination with cellular demands. In mammals, nuclear-encoded microRNAs were found associated with the mitochondria. Some of these contribute to the regulation of mitochondrial transcription and translation. Others were proposed to be stored in the organelles and to be released for regulation of nuclear transcripts. Further ncRNAs of various sizes derive from the mitochondrial genome and it was speculated that organelles host antisense or RNA interference pathways. Long ncRNAs mapping to the mitochondrial DNA seem to operate in the nucleus. Altogether, the origin and trafficking of ncRNAs categorized as mitochondrial in mammals raise questions far beyond the current knowledge. In protozoa, hundreds of guide RNAs specify editing events needed to generate functional messenger RNAs. Only few ncRNAs have been reported in plant mitochondria, but editing sites were revealed in non-coding regions of the organellar genome, suggesting that the corresponding transcripts have a function. Conversely, numerous ncRNA candidates were identified in chloroplasts, essentially mapping to the plastid genome. A synthetic view of the data with their functional implications is given here.

SOLAR PROMINENCES: “DOUBLE, DOUBLE… BOIL AND BUBBLE”

Observations revealed rich dynamics within prominences, the cool 10,000 K, macroscopic (sizes of order 100 Mm) "clouds" in the million degree solar corona. Even quiescent prominences are continuously perturbed by hot, rising bubbles. Since prominence matter is hundredfold denser than coronal plasma, this bubbling is related to Rayleigh-Taylor instabilities. Here we report on true macroscopic simulations well into this bubbling phase, adopting a magnetohydrodynamic description from chromospheric layers up to 30 Mm height. Our virtual prominences rapidly establish fully non-linear (magneto)convective motions where hot bubbles interplay with falling pillars, with dynamical details including upwelling pillars forming within bubbles. Our simulations show impacting Rayleigh-Taylor fingers reflecting on transition region plasma, ensuring that cool, dense chromospheric material gets mixed with prominence matter up to very large heights. This offers an explanation for the return mass cycle mystery for prominence material. Synthetic views at extreme ultraviolet wavelengths show remarkable agreement with observations, with clear indications of shear-flow induced fragmentations.

Results of the pilot assistance system “Assisted Low-Level Flight and Landing on Unprepared Landing Sites” obtained with the ACT/FHS research rotorcraft

The DLR project ALLFlight (Assisted Low-Level Flight and Landing on Unprepared Landing Sites) deals with the development of a helicopter pilot assistance system, to provide pilot assistance during all phases of flight. The research is particularly focused on the landing on unprepared sites in the presence of obstacles and in a degraded visual environment. The goal is to compute a safe flight path in real time that is displayed to the pilot. Several technical components such as a sensor suite to scan the environment, path planning algorithms, head-down and helmet-mounted displays, active inceptors, and the model-based flight control system are set up to form the overall assistance system. Throughout the development, pilot surveys generate requirements to design individual components such as path planning algorithms, or the synthetic view of the helmet-mounted display. Prior surveys accelerate the design and adjustment of the respective components, meaning that the flight tests benefit from well-designed components, minimizing the requirement for further “re-designs”. During ALLFlight, the successfully flight-tested manual landing with path planning and obstacle avoidance in real time for an unknown terrain has been demonstrated. This paper describes each assistance component, the pilot surveys, and the results obtained in almost six years of research.

Favouring reflexivity in technology-enhanced learning systems: towards smart uses of traces

During learning activities, reflexive processes allow learners to realise what they have done, understand why, decide on new actions and gain motivation. They help learners to regulate their actions by themselves, that is, to develop metacognitive regulation skills. Computer environments can support reflexive processes to support human learning, for example by analysing traces of learner activity and providing synthetic views by the way of indicators. Nevertheless, traces are underused in technology-enhanced learning (TEL) systems. In this article, we draw up the potential and limits of TEL systems based on traces for reflexive purposes. We then highlight the characteristics which TEL systems should have to use traces to foster reflexivity. We finally discuss how systems could enrich the self-confrontation process with traces.

Modeling 3D synthetic view dissimilarity

We model the dissimilarity among 3D synthetic views and measure the novelty of a view by its dissimilarity to other view(s). Two views are dissimilar if they have different viewing content or viewing orientations. The model evaluates the perceptual cost of mentally reconstructing one view from other view(s). Higher perceptual cost means more dissimilarity. Perceptual cost is related to reaction time of rotation and completion of human mental images. Visual comparisons among dissimilarity measures suggest that our model can better determine how dissimilar one view is to other view(s).

The gravity apple tree

The gravity apple tree is a genealogical tree of the gravitation theories developed during the past century. The graphic representation is full of information such as guides in heuristic principles, names of main proponents, dates and references for original articles (See under Supplementary Data for the graphic representation). This visual presentation and its particular classification allows a quick synthetic view for a plurality of theories, many of them well validated in the Solar System domain. Its diachronic structure organizes information in a shape of a tree following similarities through a formal concept analysis. It can be used for educational purposes or as a tool for philosophical discussion.

Third Body Concept and Wear Particle Behavior in Dry Friction Sliding Conditions

The third body concept is a pragmatic tool for analyzing and understanding the friction and wear of sliding materials. This approach is based on the dominating role played by the wear particles under dry sliding conditions. These particles constitute the major part of what is called the third body. The third body concept was introduced by Maurice Godet in the middle of the 70’s and developed by Yves Berthier since the end of the 80’s who added complementary conceptual tools as the tribological triplet, the accommodation mechanisms and the tribological circuit. The aim of this paper is to give a synthetic view of these concepts, which involves mechanical, material and physicochemical subjects. Concrete examples and case studies from various practical applications are given to illustrate the validity and the efficiency of such a phenomenological approach.

Augmented Command and Control Table to Support Network-Centric Operations

The success in network-centric warfare requires information superiority to obtain dominant battlespace awareness. The time required to take a decision has been reduced by orders of magnitude, while the volume of accessible data has been increased exponentially. When this volume is displayed to an operator, the risk of reaching a state of information overload is real and great care shall be taken to make sure that what is provided is actually information and not noise. In this paper we propose a novel interaction environment that leverages the augmented reality technology to provide a digitally enhanced view of a real command and control table. The operator equipped with an optical see-through head-mounted display controls the virtual context, a synthetic view of the common operational picture, remaining connected to the real world. Technical details of the system are described together with the evaluation method. The results showed effectiveness of the proposed system in terms of understanding perception, depth impression, and level of immersion. A relevant reduction of the reaction time and of the number of errors made during the execution of complex tasks, have been obtained.Defence Science Journal, Vol. 65, No. 1, January 2015, pp.39-45, DOI:http://dx.doi.org/10.14429/dsj.65.6713

Statistical inferences under the Null hypothesis: common mistakes and pitfalls in neuroimaging studies.

Published studies using functional and structural MRI include many errors in the way data are analyzed and conclusions reported. This was observed when working on a comprehensive review of the neural bases of synesthesia, but these errors are probably endemic to neuroimaging studies. All studies reviewed had based their conclusions using Null Hypothesis Significance Tests (NHST). NHST have yet been criticized since their inception because they are more appropriate for taking decisions related to a Null hypothesis (like in manufacturing) than for making inferences about behavioral and neuronal processes. Here I focus on a few key problems of NHST related to brain imaging techniques, and explain why or when we should not rely on “significance” tests. I also observed that, often, the ill-posed logic of NHST was even not correctly applied, and describe what I identified as common mistakes or at least problematic practices in published papers, in light of what could be considered as the very basics of statistical inference. MRI statistics also involve much more complex issues than standard statistical inference. Analysis pipelines vary a lot between studies, even for those using the same software, and there is no consensus which pipeline is the best. I propose a synthetic view of the logic behind the possible methodological choices, and warn against the usage and interpretation of two statistical methods popular in brain imaging studies, the false discovery rate (FDR) procedure and permutation tests. I suggest that current models for the analysis of brain imaging data suffer from serious limitations and call for a revision taking into account the “new statistics” (confidence intervals) logic.

A data-centric approach to manage business processes

We proposed, in previous works, a business process execution language for data-driven workflow modeling, verification, and execution; the proposed model can present both control flow and shared data in workflow processes. It can be analyzed to verify its correctness before its deployment. In this paper, we are going to improve the semantics of our approach to allow better integration between data and control flow, and between the workflow and its external environment (such as relational databases and XML documents). We are also going to extend our approach to generate multidimensional data models, namely OLAP hypercubes, from data handled by the workflow, in order to provide synthetic view of data for decision makers.

Model checking to assess T-helper cell plasticity.

Computational modeling constitutes a crucial step toward the functional understanding of complex cellular networks. In particular, logical modeling has proven suitable for the dynamical analysis of large signaling and transcriptional regulatory networks. In this context, signaling input components are generally meant to convey external stimuli, or environmental cues. In response to such external signals, cells acquire specific gene expression patterns modeled in terms of attractors (e.g., stable states). The capacity for cells to alter or reprogram their differentiated states upon changes in environmental conditions is referred to as cell plasticity. In this article, we present a multivalued logical framework along with computational methods recently developed to efficiently analyze large models. We mainly focus on a symbolic model checking approach to investigate switches between attractors subsequent to changes of input conditions. As a case study, we consider the cellular network regulating the differentiation of T-helper (Th) cells, which orchestrate many physiological and pathological immune responses. To account for novel cellular subtypes, we present an extended version of a published model of Th cell differentiation. We then use symbolic model checking to analyze reachability properties between Th subtypes upon changes of environmental cues. This allows for the construction of a synthetic view of Th cell plasticity in terms of a graph connecting subtypes with arcs labeled by input conditions. Finally, we explore novel strategies enabling specific Th cell polarizing or reprograming events.

Phase equilibria of methyl esters in supercritical propane

High pressure phase equilibria measurements using a static synthetic view cell for methyl decanoate, methyl dodecanoate, methyl hexadecanoate, methyl octadecaonate and methyl docosanoate in supercritical propane were conducted between 376.6 and 412.4K at methyl ester mass fractions between 0.0178 and 0.660. The data show a linear increase in phase transition pressure with an increase in temperature at constant composition and, within the experimental range, total solubility was achieved below 8.1MPa for all systems. Comparing the various data sets, an increase in phase transition pressure with increasing hydrocarbon backbone is noted, indicating that propane is able to fractionate a mixture of methyl esters.

Transformation and human use of forests in the Western Pyrenees during the Holocene based on archaeological wood charcoal

In this paper, we present a synthetic view of the results of anthracological studies in the Western Pyrenean Region during the Holocene. With this aim, we have compiled the results of wood charcoal analyses from archaeological sites taking into account that this region can be divided into several biogeographic areas. Firstly, we present the Aizpea archaeological site in the Pyrenees. Secondly, the deposits of Pico Ramos, Kobeaga II and El Mirón in the Coastal Area are described. Moving to the central part, into the Transition area, we describe the data of Mendandia as the main representative site, although the nearby sites of Atxoste, Kampanoste, and Kanpanoste Goikoa are also mentioned. Finally, for the southern sector of the Ebro Valley, we explain the archaeological sites of Peña Parda and Peña Larga. In addition, some specific issues that have been observed in some plant species found in this environment are also addressed. The main results show the use of different types of wood located near the archaeological sites and, in some particular cases, the selection of one of them.

The family of K2P channels: salient structural and functional properties.

Potassium channels participate in many biological functions, from ion homeostasis to generation and modulation of the electrical membrane potential. They are involved in a large variety of diseases. In the human genome, 15 genes code for K(+) channels with two pore domains (K2P ). These channels form dimers of pore-forming subunits that produce background conductances finely regulated by a range of natural and chemical effectors, including signalling lipids, temperature, pressure, pH, antidepressants and volatile anaesthetics. Since the cloning of TWIK1, the prototypical member of this family, a lot of work has been carried out on their structure and biology. These studies are still in progress, but data gathered so far show that K2P channels are central players in many processes, including ion homeostasis, hormone secretion, cell development and excitability. A growing number of studies underline their implication in physiopathological mechanisms, such as vascular and pulmonary hypertension, cardiac arrhythmias, nociception, neuroprotection and depression. This review gives a synthetic view of the most noticeable features of these channels.

Mistyczna teoria odkupienia w pismach św. Grzegorza z Nyssy

The mystical theory of redemption in the writings of Gregory of Nyssa is concentrated on contemplating the mistery of Incarnation – inclusion of deificated human nature of Jesus Christ in the monad of humanity. This unity is the structural ground of co-deification of humanity and it enables human nature to achieve its initial mission-imitating the Personal Image of God, revealed in the Incarnated. The objective deification, donated humanity, elaborated by Gregory in the imagery of first fruits leavening with their own sanctity the cake of human nature, derives its causative power from perichoresis of Jesus Christ nature. Intercession of the Son of God enables humanity to regain participation in God, lost because of sin and it establishes the icon of a synthetic homogenous view of salvation of man.

TGG-based process for automating the transformation of UML models towards B specifications

The UML notation provides a standard framework for the purpose of object modelling by several diagrams (classes, statecharts, etc.). These form confirmed advantages: re-use of components, high level of abstraction, semantic richness, graphic and synthetic view. Nevertheless, the object-oriented notations lack of formalisation and miss of reliable bases for the analysis and verification of the applications. To overcome this problem, we suggest a solution to the UML graph transformation towards formal methods, in particular the B method. The goal of this paper is to automate the generation of B language, starting from UML class and statechart diagrams by mean of graph grammar rules. This automation is achieved by the tool TGG Interpreter. The major advantage of this transformation: it is a declarative; visual; and formal approach to handle graphs. A lift control system is developed to illustrate our study.

Understanding room-temperature metastability of graphene oxide utilizing hydramines from a synthetic chemistry view

The mechanism investigation of room-temperature simultaneous covalent/noncovalent functionalization reveals that metastable graphene oxide could be regarded as an active platform for various reactions.

On the electromagnetic scattering of arbitrary shaped beams by arbitrary shaped particles: A review

Since the development of Lorenz–Mie theory describing the electromagnetic scattering of a plane wave by a homogeneous spherical particle, light scattering theories (and applications) have essentially developed along two streams (i) from plane wave to arbitrary shaped beams and (ii) from homogeneous spherical particles to arbitrary shaped particles. The present paper presents a review devoted to a synthetic and unified view of these two streams.