Minimal Trace Research Articles

Seismic stratigraphy and sedimentary facies analysis of the pre- and syn- Messinain salinity crisis sequences, onshore Nile Delta, Egypt: Implications for reservoir quality prediction

Abstract This study provides the first high-resolution outlines of the Messinian sequence in the Nile Delta based on an integrated sedimentological, petrophysical and seismic stratigraphic approach. The distribution, pattern and architecture of the Messinian facies deposited before, during and after the Messinian salinity crisis (MSC) have been investigated. In seismic, the pre-MSC Qawasim Formation constitutes parallel oblique seismic facies interpreted as deltaic system prograding northward from prodelta, distal sand bars into subaqueous distributary channels and mouthbars and subaerial delta-plain distributary channels. The MSC Abu Madi Formation consists of three seismic-stratigraphic units infilling the Eonile canyon. A seismically chaotic lower unit paving the canyon-floor is overlain by the continuous, high-amplitude reflectors of the middle unit which is capped by semi-chaotic, low-amplitude facies of the upper unit. The lower unit corresponds to the subaerial gravity-flow deposits synchronously accumulated during the Eonile incision; whereas the middle unit comprises the aggradational-progradational fluvial facies, and the upper unit constitutes the retrogradational estuarine facies. The superimposed diagenetic alterations on these various depositional facies produced complex reservoir heterogeneity. Fluid flow conduits are restricted to the coarse-grained delta distributary channels and fluvial facies with limited marine influence and minimal depositional clay content and traces of diagenetic kaolinite and chlorite. On the other hand, flow baffles and barriers are common in the fine-grained marine-influenced facies with pervasive depositional clays, diagenetic calcite and glauconite.

Extremal values of energy over oriented bicyclic graphs

Graph energy can be extended to digraphs via the trace norm. The trace norm of a digraph is the trace norm of its adjacency matrix, i.e. the sum of its singular values. In this work we find the oriented graphs that attain minimal and maximal trace norm over the set of oriented bicyclic graphs.

Temperature Minimization and Thermal-Driven Scheduling for Real-Time Periodic Tasks

With the increasing power density of processors due to the continuous shrinking of chip size, thermal issue of real-time systems has become more and more urgent since it can greatly affect the systems’ reliability and safety. However, due to the difficulty in quantitative analysis of temperature, existing thermal-aware research either considers temperature as a constraint to minimize energy consumption treating leakage power as a constant, or minimizes the temperature qualitatively through approaches like cool-hot task execution pattern. Even the latest work also only analyzes the average temperature in thermal steady state. To this end, this paper aims at quantitatively minimizing the temperature in both steady and transient states while considering the effect of temperature on leakage power. The following contributions have been made: presents a method of task construction, based on which the minimal temperature condition for any scheduling algorithm like GPS (Global Processor Sharing) and EDF (Earliest Deadline First) under both steady and transient states is proved; discovers a thermal law exhibited by tasks’ power consumption, based on which a thermal-aware approximate algorithm of GPS with a relatively longer scheduling length is designed to mitigate the higher switching overhead of GPS scheduling while guaranteeing the tasks’ timing constraints. Sufficient experiments validate the minimal temperature condition and thermal-aware scheduling algorithm. The two important conclusions obtained from this work are: (1) when the optimal condition can be achieved, all of the scheduling algorithms like GPS and EDF result in the same minimal temperature traces since all of the tasks share the same power consumption value and the processor is fully utilized; (2) when not, the executing sequence of tasks in a scheduling interval of the approximate GPS scheduling, which is determined based on the thermal law, exhibits a better thermal-aware feature.

SpyCatcher-NTEV: A Circularly Permuted, Disordered SpyCatcher Variant for Less Trace Ligation.

The SpyTag/SpyCatcher reaction has emerged as a powerful way for bioconjugation, but it leaves a folded complex in the product after the formation of the isopeptide bond. To vary the location of the reactive residue and reduce the size of the complex and its potential immunogenicity, we engineer two circularly permuted SpyCatcher variants, SpyCatcher-N and SpyCatcher-NTEV, the latter of which possesses a TEV-recognition site for removal of the fragment containing the catalytic site. Surprisingly, both variants are found to be disordered in solution, yet still retain the ability to form an ordered complex upon reaction with SpyTag with second-order rate constants of ∼10 M-1 s-1. Cellular expression of a telechelic protein bearing SpyCatcher-NTEV at the N-terminus and SpyTag at the C-terminus gives both cyclized and chain-extended products. Notably, the monomers exist almost exclusively in the cyclic form owing to its high reactivity in vivo. The fragment containing the catalytic site of SpyCatcher-NTEV can then be removed by TEV digestion, giving a circular protein with minimal trace from the ligation reaction. The plasticity of SpyTag/SpyCatcher reactive pair has promised an ever-expanding toolbox of genetically encoded peptide-protein reaction with versatile features.

Oriented bipartite graphs with minimal trace norm

The trace norm of a digraph D is the trace norm of its adjacency matrix A (i.e. the sum of the singular values of A). In particular, when G is a graph then its trace norm is the well-known energy of G introduced by I. Gutman in 1978. In this paper, we address the following problem: among all orientations of a given bipartite graph, which has minimal trace norm? We show that the minimal trace norm is attained in sink-source orientations (i.e. orientations in which every vertex is a sink vertex or a source vertex). Consequently, if is a set of connected bipartite graphs with minimal energy G, then the sink-source orientations of G have minimal trace norm among all orientations of graphs in . This is a consequence of our main result which relates the energy of a graph with the trace norm of its orientations. As another application we find the extremal values of the trace norm among all orientations of unicyclic graphs.

Different equivalent approaches to the geodetic reference system

A new approach to the determination of least-squares solutions for the rank deficient model is presented, which, in place of the classical minimal constraints, utilizes the expression of the excess parameters as a function of a subset of unknown parameters describing the model without ambiguities. The role of the lack of reference system definition in the resulting rank deficiency is explained, first for the original non-linear model case, and is specialized next to the linearized model. The whole set of solutions is parameterized in terms of two matrices defining the linearized relation from the model describing parameters to the remaining ones. Particular values are obtained for the case of solution with minimal trace of its covariance matrix, as well for the solution for minimum norm. Finally, the connection with the existing classical approach is established, while the approach is further elaborated in terms of the full-rank decompositions of the model design matrix.

Forensic DNA methylation profiling from minimal traces: How low can we go?

Analysis of human DNA methylation (DNAm) can provide additional investigative leads in crime cases, e.g. the type of tissue or body fluid, the chronological age of an individual, and differentiation between identical twins. In contrast to the genetic profile, the DNAm level is not the same in every cell. At the single cell level, DNAm represents a binary event at a defined CpG site (methylated versus non-methylated). The DNAm level from a DNA extract however represents the average level of methylation of the CpG of interest of all molecules in the forensic sample. The variance of DNAm levels between replicates is often attributed to technological issues, i.e. degradation of DNA due to bisulfite treatment, preferential amplification of DNA, and amplification failure. On the other hand, we show that stochastic variations can lead to gross fluctuation in the analysis of methylation levels in samples with low DNA levels. This stochasticity in DNAm results is relevant since low DNA amounts (1pg – 1ng) is rather the norm than the exception when analyzing forensic DNA samples.This study describes a conceptual analysis of DNAm profiling and its dependence on the amount of input DNA. We took a close look at the variation of DNAm analysis due to DNA input and its consequences for different DNAm-based forensic applications.As can be expected, the 95%-confidence interval of measured DNAm becomes narrower with increasing amounts of DNA. We compared this aspect for two different DNAm-based forensic applications: body fluid identification and chronological age determination. Our study shows that DNA amount should be well considered when using DNAm for forensic applications.

RNA/DNA co-analysis from bloodstains on aged polyvinyl-alcohol gloves prepared for securing evidence from the hands of victims of fatal gunshot injuries.

In contrast to cumulative techniques (e.g., tape-lift) for qualitative gunshot residues (GSR) analysis, topographic methods are commonly applied to preserve the integrity of evidence from a shooter's or victim's hand in cases of gun-related crimes. Topographic sampling techniques employing adhesive foils, latex, or the polyvinyl alcohol (PVAL) method enable unambiguous sampling of biological and non-biological trace material while preserving its spatial distribution and relation to each other. The PVAL method in particular allows for a topographically veridic and quantitative conservation of traces of GSR and biological stains that are embedded in the PVAL glove, because it completely removes these traces from the hand. The present study investigated the success rates of STR profiling and the detection of blood and brain-specific gene expression from minimal traces of blood splatter as well as parallel to the positive detection of gunshot residues embedded in 17 PVAL gloves taken from the hands of deceased persons in the context of homicide cases in the period between 1996 and 2003. The water-soluble PVAL matrix is shown to be fully compatible with successful STR profiling and the detection of blood- and brain-specific miRNA expression, even after up to 20years of storage, demonstrating that this sampling technique offers advantages compared to other more simplistic sampling methods like taping.

The importance of ensuring quality and minimising the risks of contamination in genetics forensic analysis

The high sensitivity achieved in genetic analysis of forensic interest allows to obtain genetic profiles from minimal traces of biological material deposited on the evidence before or even subsequent to the events under investigation. Accidental contamination of biological evidence and erroneous interpretation of genetic findings have important implications with the consequent impact on the judicial process. Minimising and detecting the presence of accidental contamination that may be generated during some phases of collection of samples or genetic analysis are a priority for forensic genetics laboratories. This article reviews legislation and national and international standards applicable to field of forensic genetics, which aim to ensure the quality of expert evidence and the reliability of the conclusions reached in the expert reports.

La importancia de garantizar la calidad y minimizar los riesgos de contaminación en el análisis genético forense

The high sensitivity achieved in genetic analysis of forensic interest allows to obtain genetic profiles from minimal traces of biological material deposited on the evidence before or even subsequent to the events under investigation. Accidental contamination of biological evidence and erroneous interpretation of genetic findings have important implications with the consequent impact on the judicial process. Minimising and detecting the presence of accidental contamination that may be generated during some phases of collection of samples or genetic analysis are a priority for forensic genetics laboratories. This article reviews legislation and national and international standards applicable to field of forensic genetics, which aim to ensure the quality of expert evidence and the reliability of the conclusions reached in the expert reports.

Forensic science at a crossroads

Forensic science is at a critical crossroads, caught between the sky-high, unrealistic expectations of its capabilities amongst jurors and the judiciary, and omitting DNA analysis - the reality that many techniques and technologies are decades old, based on minimal basic science. There is a vast dichotomy between fictional television dramas where crime scene investigators provide definitive answers in next to no time from minimal trace evidence and the capabilities of real forensics, where samples are often incomplete and analysis takes several weeks. It is therefore vital for forensic professionals to educate everyone in the criminal justice system about technology available to them today, as well as its limitations, while also working to develop the underpinning science and technology.

Deformation-induced trace element redistribution in zircon revealed using atom probe tomography.

Trace elements diffuse negligible distances through the pristine crystal lattice in minerals: this is a fundamental assumption when using them to decipher geological processes. For example, the reliable use of the mineral zircon (ZrSiO4) as a U-Th-Pb geochronometer and trace element monitor requires minimal radiogenic isotope and trace element mobility. Here, using atom probe tomography, we document the effects of crystal–plastic deformation on atomic-scale elemental distributions in zircon revealing sub-micrometre-scale mechanisms of trace element mobility. Dislocations that move through the lattice accumulate U and other trace elements. Pipe diffusion along dislocation arrays connected to a chemical or structural sink results in continuous removal of selected elements (for example, Pb), even after deformation has ceased. However, in disconnected dislocations, trace elements remain locked. Our findings have important implications for the use of zircon as a geochronometer, and highlight the importance of deformation on trace element redistribution in minerals and engineering materials.

Parametric Modeling Investigation for Radially Staged Low-Emission Combustion

Aviation gas-turbine combustion demands high efficiency, wide operability, and minimal trace gas emissions. Performance critical design parameters include injector geometry, combustor layout, fuel–air mixing, and engine cycle conditions. The present investigation explores these factors and their impact on a radially staged low-emission aviation combustor sized for a next-generation 24,000-lbf-thrust engine. By coupling multifidelity computational tools, a design exploration was performed using a parameterized annular combustor sector at projected 100% takeoff power conditions. Design objectives included nitrogen oxide emission indices and overall combustor pressure loss. From the design space, an optimal configuration was selected and simulated at 7.1, 30, and 85% part-power operation, corresponding to landing–takeoff cycle idle, approach, and climb segments. All results were obtained by solution of the steady-state Reynolds-averaged Navier–Stokes equations. Species concentrations were solved directly using a reduced 19-step reaction mechanism for Jet A. Turbulence closure was obtained using a nonlinear model. This research demonstrates revolutionary combustor design exploration enabled by multifidelity physics-based simulation.

Adaptive-Robust Stabilization of the Furuta's Pendulum Via Attractive Ellipsoid Method

This paper focuses on the issue of adaptive-robust stabilization of the Furuta's pendulum around unstable equilibrium where the dynamical model is unknown. The control scheme lies at the lack of the dynamical model as well as external disturbances. The stabilization analysis is based on the attractive ellipsoid method (AEM) for a class of uncertain nonlinear systems having “quasi-Lipschitz” nonlinearities. Even more, a modification of the AEM concept that permits to use online information obtained during the process is suggested here. This adjustment (or adaptation) is made only in some fixed sample times, so that the corresponding gain matrix of the robust controller is given on time interval too. Furthermore, under a specific “regularized persistent excitation condition,” the proposed method guarantees that the controlled system trajectories remain inside an ellipsoid of a minimal size (the minimal size is refereed to as the minimal trace of the corresponding inverse ellipsoidal matrix). Finally, the adaptive process describes a region of attraction (ROA) of the considered system under adaptive-robust nonlinear control law.

Experimental demonstration of single electron transistors featuring SiO2 plasma-enhanced atomic layer deposition in Ni-SiO2-Ni tunnel junctions

The authors report the use of plasma-enhanced atomic layer deposition (PEALD) to fabricate single-electron transistors (SETs) featuring ultrathin (≈1 nm) tunnel-transparent SiO2 in Ni-SiO2-Ni tunnel junctions. They show that, as a result of the O2 plasma steps in PEALD of SiO2, the top surface of the underlying Ni electrode is oxidized. Additionally, the bottom surface of the upper Ni layer is also oxidized where it is in contact with the deposited SiO2, most likely as a result of oxygen-containing species on the surface of the SiO2. Due to the presence of these surface parasitic layers of NiO, which exhibit features typical of thermally activated transport, the resistance of Ni-SiO2-Ni tunnel junctions is drastically increased. Moreover, the transport mechanism is changed from quantum tunneling through the dielectric barrier to one consistent with thermally activated resistors in series with tunnel junctions. The reduction of NiO to Ni is therefore required to restore the metal-insulator-metal (MIM) structure of the junctions. Rapid thermal annealing in a forming gas ambient at elevated temperatures is presented as a technique to reduce both parasitic oxide layers. This method is of great interest for devices that rely on MIM tunnel junctions with ultrathin barriers. Using this technique, the authors successfully fabricated MIM SETs with minimal trace of parasitic NiO component. They demonstrate that the properties of the tunnel barrier in nanoscale tunnel junctions (with <10−15 m2 in area) can be evaluated by electrical characterization of SETs.

Limits to catalysis in quantum thermodynamics

Quantum thermodynamics is a research field that aims at fleshing out the ultimate limits of thermodynamic processes in the deep quantum regime. A complete picture of thermodynamical processes naturally allows for auxiliary systems dubbed ‘catalysts’, i.e., any physical systems facilitating state transformations while remaining essentially intact in their state, like an auxiliary system, a clock, or an actual catalyst. In this work, we present a comprehensive analysis of the power and limitation of such thermal catalysis. Specifically, we provide a family of optimal catalysts that can be returned with minimal trace distance error after facilitating a state transformation process. To incorporate the genuine physical role of a catalyst, we identify very significant restrictions on arbitrary state transformations under dimension or mean energy bounds, using methods of convex relaxations. We discuss the implication of these findings on possible thermodynamic state transformations in the quantum regime.

TRACES ON SEMIGROUP RINGS AND LEAVITT PATH ALGEBRAS

AbstractThe trace on matrix rings, along with the augmentation map and Kaplansky trace on group rings, are some of the many examples of linear functions on algebras that vanish on all commutators. We generalize and unify these examples by studying traces on (contracted) semigroup rings over commutative rings. We show that every such ring admits a minimal trace (i.e., one that vanishes only on sums of commutators), classify all minimal traces on these rings, and give applications to various classes of semigroup rings and quotients thereof. We then study traces on Leavitt path algebras (which are quotients of contracted semigroup rings), where we describe all linear traces in terms of central maps on graph inverse semigroups and, under mild assumptions, those Leavitt path algebras that admit faithful traces.

PTH-201 Factors affecting the efficacy of needlefree connector disinfection: Abstract PTH-201 Table 1

Introduction Needlefree connector contamination can lead to central venous catheter related bloodstream infection (CRBSI). Differences in connector design such as a smooth or irregular septum surface and/or a tight seal between the septum and the connector housing can impede disinfection. Disparity between protocols; disinfectant contact time, disinfection method (if the surface is wiped in one direction or back and forth) and inter rater variation may also affect results. This invitro study aimed to assess these variables on the macroscopic contamination of different connectors. Method The surfaces of 5 different needlefree connectors were contaminated with ultraviolet (UV) disclosing lotion (invisible to the naked eye). 3 raters subsequently wiped the connectors with 2% chlorhexidine and 70% isopropyl alcohol wipes using a friction rub for 0 (control) 3, 5, 15 and 30 secs. Using UV light the amount of residual lotion on the connectors was assessed and scored accordingly; 100 if there was no trace of lotion, 75 a minimal trace, 50 a moderate trace and 25 if a large trace remained. These values were decided by 2 raters. The procedure was then repeated following the application of 70% isopropyl alcohol port protection caps to the connector for 5 min before disinfection. Results The mean score ±standard deviation from all connectors and all raters is shown below. Variation between devices was significant p The mean score for disinfecting 10 secs. This difference was significant p Conclusion The results from this study demonstrated differences in the removal of macroscopic contamination from needlefree connectors. These differences most likely reflect variation in the surface topography of the individual connectors. Disinfecting for 10 secs or more was more effective than less than 10 secs, with 15 secs being as effective as 30 suggesting a minimum of 15 secs is sufficient. There was variation between raters but this was minimised by using a 70% isopropyl alcohol port protector. The extent to which these results could impact upon the development of CRBSI will be the focus of future study. Disclosure of interest None Declared.

On the application of the method of difference potentials to linear elastic fracture mechanics

SummaryThe Difference Potential Method (DPM) proved to be a very efficient tool for solving boundary value problems (BVPs) in the case of complex geometries. It allows BVPs to be reduced to a boundary equation without the knowledge of Green's functions. The method has been successfully used for solving very different problems related to the solution of partial differential equations. However, it has mostly been considered in regular (Lipschitz) domains. In the current paper, for the first time, the method has been applied to a problem of linear elastic fracture mechanics. This problem requires solving BVPs in domains containing cracks. For the first time, DPM technology has been combined with the finite element method. Singular enrichment functions, such as those used within the extended finite element formulations, are introduced into the system in order to improve the approximation of the crack tip singularity. Near‐optimal convergence rates are achieved with the application of these enrichment functions. For the DPM, the reduction of the BVP to a boundary equation is based on generalised surface projections. The projection is fully determined by the clear trace. In the current paper, for the first time, the minimal clear trace for such problems has been numerically realised for a domain with a cut. Copyright © 2015 John Wiley & Sons, Ltd.

Optimal observability of the multi-dimensional wave and Schrödinger equations in quantum ergodic domains

We consider the wave and Schrödinger equations on a bounded open connected subset \Omega of a Riemannian manifold, with Dirichlet, Neumann or Robin boundary conditions whenever its boundary is nonempty. We observe the restriction of the solutions to a measurable subset \omega of \Omega during a time interval [0, T] with T>0 . It is well known that, if the pair (\omega,T) satisfies the Geometric Control Condition ( \omega being an open set), then an observability inequality holds guaranteeing that the total energy of solutions can be estimated in terms of the energy localized in \omega \times (0, T) . We address the problem of the optimal location of the observation subset \omega among all possible subsets of a given measure or volume fraction. A priori this problem can be modeled in terms of maximizing the observability constant, but from the practical point of view it appears more relevant to model it in terms of maximizing an average either over random initial data or over large time. This leads us to define a new notion of observability constant, either randomized, or asymptotic in time. In both cases we come up with a spectral functional that can be viewed as a measure of eigenfunction concentration. Roughly speaking, the subset \omega has to be chosen so to maximize the minimal trace of the squares of all eigenfunctions. Considering the convexified formulation of the problem, we prove a no-gap result between the initial problem and its convexified version, under appropriate quantum ergodicity assumptions, and compute the optimal value. Our results reveal intimate relations between shape and domain optimization, and the theory of quantum chaos (more precisely, quantum ergodicity properties of the domain \Omega ). We prove that in 1D a classical optimal set exists only for exceptional values of the volume fraction, and in general one expects relaxation to occur and therefore classical optimal sets not to exist. We then provide spectral approximations and present some numerical simulations that fully confirm the theoretical results in the paper and support our conjectures. Finally, we provide several remedies to nonexistence of an optimal domain. We prove that when the spectral criterion is modified to consider a weighted one in which the high frequency components are penalized, the problem has then a unique classical solution determined by a finite number of low frequency modes. In particular the maximizing sequence built from spectral approximations is stationary.