High-Resolution Correlation Using Geophysical and Geochemical Methods on Three Cambrian Drumian Marine Sedimentary Successions in The House Range Embayment, Western Laurentia

The Global boundary Stratotype Section and Point (GSSP) of the base of the Cambrian Drumian Stage was defined at 62 m above the base of the Wheeler formation, at the First Appearance Datum (FAD) of Ptychagnostus atavus (P. atavus), and at 10 meter below the DrumIan Carbon isotope Excursion (DICE) on the Stratotype Ridge in the Drum Mountains western Utah, (Babcock at al., 2004; 2007). Tracing the base of the the Drumian stage to other Middle Cambrian sequences in the House Range Embayment (HRE), a fault-controlled deep-water intrusion into an extensive carbonate platform along the passive margin of western Laurentia, was tentative and uncertain. The complex lithological variations, the absence of lithostratigraphic and other reliable biostratigraphic markers, and the widely-spaced sampling and coarse correlation among HRE sections, have contributed to such uncertainty. This study focuses on regional high-resolution correlation among the Drumian GSSP section, the Marjum Pass section, and the Packrat section. The objective of this research is to account for such complex facies variations, and constrain not only the base of the Drumian Stage but also the Lowest Occurrence Observed Point (LOOP)/FAD of P. atavus, and the DICE within the HRE. The HRE lithological variations follow broad facies patterns. Carbonates dominate at the edges of the HRE and decrease inward, while detrital materials dominate along the HRE trough and decrease outward. Three storm layers helped in tracing important surfaces including the base of the Drumian Stage from one section into the other. Unfortunately, the GSSP was defined based on reworked P. atavus specimens at the base of the first storm layer that has an erosional base and is composed of reworked sediments. Therefore, the FAD/LOOP of P. atavus is diachronous and its acme is synchronous within the three studied sections. It is concluded also that the DICE is a chronostratigraphic marker that constrain the base of the Drumian Stage in the embayment and the nearby southern platform sections unless suppressed by the incoming heavy-isotopic platform carbonates. The DICE maximum negative 13C excursion is synchronous while the onset and the end of the DICE are diachronous

Simultaneously Sparse Solutions to Linear Inverse Problems with Multiple System Matrices and a Single Observation Vector

A linear inverse problem is proposed that requires the determination of multiple unknown signal vectors. Each unknown vector passes through a different system matrix and the results are added to yield a single observation vector. Given the matrices and lone observation, the objective is to find a simultaneously sparse set of unknown vectors that solves the system. We will refer to this as the multiple-system single-output (MSSO) simultaneous sparsity problem. This manuscript contrasts the MSSO problem with other simultaneous sparsity problems and conducts a thorough initial exploration of algorithms with which to solve it. Seven algorithms are formulated that approximately solve this NP-Hard problem. Three greedy techniques are developed (matching pursuit, orthogonal matching pursuit, and least squares matching pursuit) along with four methods based on a convex relaxation (iteratively reweighted least squares, two forms of iterative shrinkage, and formulation as a second-order cone program). The algorithms are evaluated across three experiments: the first and second involve sparsity profile recovery in noiseless and noisy scenarios, respectively, while the third deals with magnetic resonance imaging radio-frequency excitation pulse design.Comment: 36 pages; manuscript unchanged from July 21, 2008, except for updated references; content appears in September 2008 PhD thesi

How Knowledge Management Implementation Affects the Performance of Egyptian Construction Companies

This study examines the effectiveness of knowledge management systems within the construction industry in Egypt from the perspective of knowledge infrastructure capability (KIC), knowledge process capability (KPC) and their impact on business performance (BP) from the financial, consumer, learning and growth, supplier and internal perspectives. The sample consists of 75 first class Egyptian construction companies. The authors used a questionnaire that was modified from the questionnaire previously used by Gold et al., (2001) and Smith (2006). The authors used one-way ANOVA, t-tests and OLS regressions. The results indicated that both knowledge infrastructure capability (KIC) and knowledge process capability (KPC) have a positive effect on business performance (BP). The results also indicate that organizations with well-developed training and development plans have significantly higher KIC and KPC scores compared to those that do not have such plans

Sustainability standards and their impact on contemporary sculpture design

Recently, all efforts aim to preserve the environment through sustainable design to activate the positive impact of the environment on human welfare and health. The sculptor has always been keeping pace with the spirit of the times, and using technology according to the requirements of each stage he lives in. He had to be the first to be interested in preserving the environment, which had a clear impact on the designs of his sculptural works, and since sustainability is achieving compatibility between man, society and his environment, and through the four principles for the application of sustainability, which are "Sustainability Scope - Resources - Technology - Sustainability Scale". The research presents how the sculptor deals with these principles to achieve presence as an active element in that environmental system through his sculptural works, which in turn lead an aesthetic message and a utilitarian goal to reach the design standards imposed by the principle of sustainability on design through three main styles exposed to applied sculptural works based on the principle of sustainability which are:1- Works implemented through the use of natural environment materials, which are sustainable and environmentally friendly.2- Works implemented through the use of waste and previously used raw materials, and transforming them into aesthetic forms.3- Works implemented through the use of contemporary technologies, which would show the data of science to serve the environment and society.The research ended by deducing the design criteria associated with the principle of sustainability and some considerations for the design standards to be taken into consideration and followed when carrying out the design process and the types of design standards that should be guided when working with sustainability as an applied sculptural trend

Lipid suppression in CSI with spatial priors and highly undersampled peripheral k-space

Mapping [superscript 1]H brain metabolites using chemical shift imaging is hampered by the presence of subcutaneous lipid signals, which contaminate the metabolites by ringing due to limited spatial resolution. Even though chemical shift imaging at spatial resolution high enough to mitigate the lipid artifacts is infeasible due to signal-to-noise constraints on the metabolites, the lipid signals have orders of magnitude of higher concentration, which enables the collection of high-resolution lipid maps with adequate signal-to-noise. The previously proposed dual-density approach exploits this high signal-to-noise property of the lipid layer to suppress truncation artifacts using high-resolution lipid maps. Another recent approach for lipid suppression makes use of the fact that metabolite and lipid spectra are approximately orthogonal, and seeks sparse metabolite spectra when projected onto lipid-basis functions. This work combines and extends the dual-density approach and the lipid-basis penalty, while estimating the high-resolution lipid image from 2-average k-space data to incur minimal increase on the scan time. Further, we exploit the spectral-spatial sparsity of the lipid ring and propose to estimate it from substantially undersampled (acceleration R = 10 in the peripheral k-space) 2-average in vivo data using compressed sensing and still obtain improved lipid suppression relative to using dual-density or lipid-basis penalty alone.National Institutes of Health (U.S.) (Grant NIH R01 EB007942)National Science Foundation (U.S.) (Grant 0643836)Siemens-MIT AllianceMIT-Center for Integration of Medicine and Innovative Technology (Medical Engineering Fellowship

MRI estimates of brain iron concentration in normal aging: Comparison of field-dependent (FDRI) and phase (SWI) methods

Different brain structures accumulate iron at different rates throughout the adult life span. Typically, striatal and brain stem structures are higher in iron concentrations in older than younger adults, whereas cortical white matter and thalamus have lower concentrations in the elderly than young adults. Brain iron can be measured in vivo with MRI by estimating the relaxivity increase across magnetic field strengths, which yields the Field-Dependent Relaxation Rate Increase (FDRI) metric. The influence of local iron deposition on susceptibility, manifests as MR phase effects, forms the basis for another approach for iron measurement, Susceptibility-Weighted Imaging (SWI), for which imaging at only one field strength is sufficient. Here, we compared the ability of these two methods to detect and quantify brain iron in 11 young (5 men, 6 women; 21 to 29 years) and 12 elderly (6 men, 6 women; 64 to 86 years) healthy adults. FDRI was acquired at 1.5 T and 3.0 T, and SWI was acquired at 1.5 T. The results showed that both methods detected high globus pallidus iron concentration regardless of age and significantly greater iron in putamen with advancing age. The SWI measures were more sensitive when the phase signal intensities themselves were used to define regions of interest, whereas FDRI measures were robust to the method of region of interest selection. Further, FDRI measures were more highly correlated than SWI iron estimates with published postmortem values and were more sensitive than SWI to iron concentration differences across basal ganglia structures. Whereas FDRI requires more imaging time than SWI, two field strengths, and across-study image registration for iron concentration calculation, FDRI appears more specific to age-dependent accumulation of non-heme brain iron than SWI, which is affected by heme iron and non-iron source effects on phase.National Institutes of Health (U.S.) (Grant AG017919)National Institutes of Health (U.S.) (Grant AA005965)National Institutes of Health (U.S.) (Grant AA017168

Simulating magnetic nanoparticle behavior in low-field MRI under transverse rotating fields and imposed fluid flow

In the presence of alternating-sinusoidal or rotating magnetic fields, magnetic nanoparticles will act to realign their magnetic moment with the applied magnetic field. The realignment is characterized by the nanoparticle's time constant, ττ. As the magnetic field frequency is increased, the nanoparticle's magnetic moment lags the applied magnetic field at a constant angle for a given frequency, Ω, in rad s[superscript −1]. Associated with this misalignment is a power dissipation that increases the bulk magnetic fluid's temperature which has been utilized as a method of magnetic nanoparticle hyperthermia, particularly suited for cancer in low-perfusion tissue (e.g., breast) where temperature increases of between 4 and 7 °C above the ambient in vivo temperature cause tumor hyperthermia. This work examines the rise in the magnetic fluid's temperature in the MRI environment which is characterized by a large DC field, B[subscript 0]. Theoretical analysis and simulation is used to predict the effect of both alternating-sinusoidal and rotating magnetic fields transverse to B[subscript 0]. Results are presented for the expected temperature increase in small tumors (~1 cm radius) over an appropriate range of magnetic fluid concentrations (0.002–0.01 solid volume fraction) and nanoparticle radii (1–10 nm). The results indicate that significant heating can take place, even in low-field MRI systems where magnetic fluid saturation is not significant, with careful the goal of this work is to examine, by means of analysis and simulation, the concept of interactive fluid magnetization using the dynamic behavior of superparamagnetic iron oxide nanoparticle suspensions in the MRI environment. In addition to the usual magnetic fields associated with MRI, a rotating magnetic field is applied transverse to the main B[subscript 0] field of the MRI. Additional or modified magnetic fields have been previously proposed for hyperthermia and targeted drug delivery within MRI. Analytical predictions and numerical simulations of the transverse rotating magnetic field in the presence of B[subscript 0] are investigated to demonstrate the effect of Ω, the rotating field frequency, and the magnetic field amplitude on the fluid suspension magnetization. The transverse magnetization due to the rotating transverse field shows strong dependence on the characteristic time constant of the fluid suspension, τ. The analysis shows that as the rotating field frequency increases so that Ωτ approaches unity, the transverse fluid magnetization vector is significantly non-aligned with the applied rotating field and the magnetization's magnitude is a strong function of the field frequency. In this frequency range, the fluid's transverse magnetization is controlled by the applied field which is determined by the operator. The phenomenon, which is due to the physical rotation of the magnetic nanoparticles in the suspension, is demonstrated analytically when the nanoparticles are present in high concentrations (1–3% solid volume fractions) more typical of hyperthermia rather than in clinical imaging applications, and in low MRI field strengths (such as open MRI systems), where the magnetic nanoparticles are not magnetically saturated. The effect of imposed Poiseuille flow in a planar channel geometry and changing nanoparticle concentration is examined. The work represents the first known attempt to analyze the dynamic behavior of magnetic nanoparticles in the MRI environment including the effects of the magnetic nanoparticle spin-velocity. It is shown that the magnitude of the transverse magnetization is a strong function of the rotating transverse field frequency. Interactive fluid magnetization effects are predicted due to non-uniform fluid magnetization in planar Poiseuille flow with high nanoparticle concentrations.R. J. Shillman Career Development AwardThomas and Gerd Perkins Professorship AwardMIT Dean's FellowshipNational Institutes of Health (U.S.) (Award R01 EB007942