Physical Sciences and Mathematics Commons^™

Integrated Analysis Of Content And Construct Validity, Byron Gajewski, Larry Price, Valorie Coffland, Diane Boyle, Marjorie Bott

Diane Kay Boyle PhD, RN, FAAN

Establishing adequacy of psychometric properties of an instrument involves acquisition and evaluation of evidence based on item content and internal structure. Content validity evidence consists of subject matter experts providing quantitative ratings of the extent to which items are a representative sample of targeted domain. Evidence of internal structure includes factor analytic studies and examination of item interrelationships based on item responses from participants. Although subject matter expert ratings and participant response data are traditionally analyzed separately, each serves to inform the other in important ways. We propose integrating subject matter experts’ and participants’ data seamlessly to establish a unified …

Gravity Wave Characteristics From Oh Airglow Imager Over Maui, Alan Liu, Xian Lu, Zhenhua Li, Gary Swenson, Steven Franke

Zhenhua Li

No abstract provided.

Implementing Namebers Using Microchip Implants: The Black Box Beneath The Skin, Katina Michael, M.G. Michael

Associate Professor Katina Michael

The use of electronic-based physical access cards to secure premises such as government buildings and large corporate offices has been in operation since the inception of bar code and magnetic-stripe cards in the 1970s. Over time, for secure access control, these first generation card technologies based on optical character recognition (OCR) and magnetic ink character recognition (MICR) were replaced by more sophisticated technologies such as smart cards and biometrics, containing encrypted data and techniques which were more difficult to dupe or to replicate \cite{michael2003a}.

An employee today wanting to gain access to their place of work, typically carries a photo …

Multiple Soliton Solutions Of (2+1)-Dimensional Potential Kadomtsev-Petviashvili Equation, Mohammad Najafi M.Najafi, Ali Jamshidi

mohammad najafi

We employ the idea of Hirota’s bilinear method, to obtain some new exact soliton solutions for high nonlinear form of (2+1)-dimensional potential Kadomtsev-Petviashvili equation. Multiple singular soliton solutions were obtained by this method. Moreover, multiple singular soliton solutions were also derived.

Daily Stock Market Movement From Oscillating Social Mood Factors, Cari Bourette

Cari Bourette

Since 2006, there has been ongoing research into the correlation of a set of oscillating mood factors and socioeconomic, geopolitical, and natural events with the goal of forecasting increased risks of destabilizing events. While promising results have been forthcoming, it has been difficult to present models that allowed those outside a small circle of specialists to participate. Between July 2007 and June 2010, weekly social mood projections, as published in monthly issues of MoodCompass, were used to develop a model to convert four oscillating mood factors into stock market expectations. This model was modified to generate signals of projected stock …

A Review Of Baobab (Adansonia Digitata) Products: Effect Of Processing Techniques, Medicinal Properties And Uses, Donatien Kabore, Hagrétou Sawadogo-Lingani, Bréhima Diawara, Clarise Compaoré, Mamoudou H. Dicko Prof., Mogens Jacobsen

Pr. Mamoudou H. DICKO, PhD

A general literature review including the effect of processing techniques, medicinal value and uses of baobab tree is reported in this manuscript. Baobab tree has multi-purpose uses, as it produces food and non-food products such as medicines, fuel, timber, fodder. Every part of the baobab tree is reported to be useful. The seeds, leaves, roots, flowers, fruit pulp and bark of baobab are edible. Baobab leaves are used in the preparation of soup. Seeds are used as a thickening agent in soups, but they can be fermented and used as a flavouring agent or roasted and eaten as snacks. The …

Risk, Odds, And Their Ratios, Joseph Hilbe

Joseph M Hilbe

A brief monograph explaining the meaning of the terms, risk, risk ratio, odds, and odds ratio and how to calculate each, together with standard errors and confidence intervals. Stata code is provided showing how all of the terms can be calculated by hand, as well as by using logistic and Poisson models.

The Massachusetts Environmental Industry: Facing The Challenges Of Maturity, Betty J. Diener, David Terkla, Erick Cooke

David G. Terkla

For most of the past 20 years, the environmental industry has been a very significant one, both in Massachusetts and across the country. Some have placed it alongside the electronics, computer hardware, software, biotechnology, fiber optics, and composite materials industries as part of the high-technology sector that has diversified and strengthened the state’s economy. Nationally, environmental industry employment exceeded that of several major manufacturing industries, including chemicals, paper, and aerospace. In the late 1990s, however, the momentum of the environmental movement began to wane. A decline in both employment and sales suggests that many of the most pressing environmental concerns …

Starting Radial Subdiffusion From A Central Point Through A Diverging Medium (A Sphere): Heat-Balance Integral Method, Jordan Hristov

Jordan Hristov

The work presents an integral solution of the time-fractional subdiffusion equation as alternative approach to those employing hypergeometric functions. The integral solution suggests a preliminary defined profile with unknown coefficients and the concept of penetration (boundary layer) well known from the heat diffusion and hydrodynamics. The profile satisfies the boundary conditions imposed at the boundary of the boundary layer that allows its coefficients to be expressed through the boundary layer depth as unique parameter describing the profile. The technique is demonstrated by a solution of a time fractional radial equation concerning anomalous diffusion from a central point source in a …

Formation Of Organized Nanostructures From Unstable Bilayers Of Thin Metallic Liquids, Mikhail Khenner, Sagar Yadavali, Ramki Kalyanaraman

Mikhail Khenner

Dewetting of pulsed-laser irradiated, thin (< 20 nm), optically reflective metallic bilayers on an optically transparent substrate with a reflective support layer is studied within the lubrication equations model. A steady-state bilayer film thickness (h) dependent temperature profile is derived based on the mean substrate temperature estimated from the elaborate thermal model of transient heating and melting/freezing. Large thermocapillary forces are observed along the plane of the liquid-liquid and liquid-gas interfaces due to this h-dependent temperature, which, in turn, is strongly influenced by the h-dependent laser light reflection and absorption. Consequently the dewetting is a result of the competition between thermocapillary and intermolecular forces. A linear analysis of the dewetting length scales established that the non-isothermal calculations better predict the experimental results as compared to the isothermal case within the bounding Hamaker coefficients. Subsequently, a computational non-linear dynamics study of the dewetting pathway was performed for Ag/Co and Co/Ag bilayer systems to predict the morphology evolution. We found that the systems evolve towards formation of different morphologies, including core-shell, embedded, or stacked nanostructure morphologies.

Determining Magnetic Nanoparticle Size Distributions From Thermomagnetic Measurements, R. Dipietro, H. Johnson, S. Bennett, T. Nummy, L. Lewis, D. Heiman

Laura H. Lewis

Thermomagnetic measurements are used to obtain the size distribution and anisotropy of magnetic nanoparticles. An analytical transformation method is described which utilizes temperature-dependent zero-field cooling (ZFC) magnetization data to provide a quantitative measurement of the average diameter and relative abundance of superparamagnetic nanoparticles. Applying this method to self-assembled MnAs nanoparticles in MnAs-GaAs composite films reveals a log-normal size distribution and reduced anisotropy for nanoparticles compared to bulk materials. This analytical technique holds promise for rapid assessment of the size distribution of an ensemble of superparamagnetic nanoparticles.

Determining Magnetic Nanoparticle Size Distributions From Thermomagnetic Measurements., R. S. Dipietro, H. G. Johnson, S. P. Bennett, T. J. Nummy, L. H. Lewis, D. Heiman

Laura H. Lewis

Thermomagnetic measurements are used to obtain the size distribution and anisotropy of magnetic nanoparticles. An analytical transformation method is described which utilizes temperature-dependent zero-field cooling magnetization data to provide a quantitative measurement of the average diameter and relative abundance of superparamagnetic nanoparticles. Applying this method to self-assembled MnAs nanoparticles in MnAs–GaAs composite films reveals a log-normal size distribution and reduced anisotropy for nanoparticles compared to bulk materials. This analytical technique holds promise for rapid assessment of the size distribution of an ensemble of superparamagnetic nanoparticles.

Magnetic Signature Of Symmetry Reduction In Epitaxial La₀.₆₇Sr₀.₃₃Mno₃ Films, Radhika Barua, L. Lewis, D. Heiman

Laura H. Lewis

The magnetic properties of epitaxially grown La0.67Sr0.33MnO3 perovskite thin films were investigated to elucidate an unexpected broken symmetry between orthogonal [100] and [010] inplane directions, resulting from the magnetostructural coupling between the film and the cubic SrTiO3 (001) substrate. The films were synthesized by molecular beam epitaxy with either complete or zero A-site cation disorder. Magnetization measured in [100] and [010] directions shows differences that signal a reduction of the in-plane cubic symmetry only for T < 290 K. The magnetization asymmetry is more robust in the film with complete A-site disorder. These results are attributed to a dominant Mn3+ character …

Universal Properties Of Linear Magnetoresistance In Strongly Disordered Mnas-Gaas Composite Semiconductors, H. G. Johnson, S. P. Bennett, R. Barua, L. H. Lewis, D. Heiman

Laura H. Lewis

Linear magnetoresistance (LMR) occurs in semiconductors as a consequence of strong electrical disorder and is characterized by nonsaturating magnetoresistance that is proportional to the applied magnetic field. By investigating a disordered MnAs-GaAs composite material, it is found that the magnitude of the LMR is numerically equal to the carrier mobility over a wide range and is independent of carrier density. This behavior is complementary to the Hall effect that is independent of the mobility and dependent on the carrier density. Moreover, the LMR appears to be insensitive to the details of the disorder and points to a universal explanation of …

Determining Magnetic Nanoparticle Size Distributions From Thermomagnetic Measurements., R. S. Dipietro, H. G. Johnson, S. P. Bennett, T. J. Nummy, L. H. Lewis, D. Heiman

Donald Heiman

Thermomagnetic measurements are used to obtain the size distribution and anisotropy of magnetic nanoparticles. An analytical transformation method is described which utilizes temperature-dependent zero-field cooling magnetization data to provide a quantitative measurement of the average diameter and relative abundance of superparamagnetic nanoparticles. Applying this method to self-assembled MnAs nanoparticles in MnAs–GaAs composite films reveals a log-normal size distribution and reduced anisotropy for nanoparticles compared to bulk materials. This analytical technique holds promise for rapid assessment of the size distribution of an ensemble of superparamagnetic nanoparticles.

Magnetotransport Properties Of Mn-Si-C Based Nanostructures, Sungmu Kang, Greg A. Brewer, Battogtokh Jugdersuren, Robert Dipietro, Don Heiman, Andrew C. Buechele, David A. Mckeown, Ian L. Pegg, John Philip

Donald Heiman

Boron-incorporated Mn5SiC nanowires were grown using chemical vapor deposition method. The nanowire cluster exhibits magnetic hysteresis loops at room temperature and the strength of the magnetic behavior depends on the concentration of the boron incorporation. Mn5SiC nanowire-based devices exhibit spin dependent transport properties which shows significant changes with boron content. Large magnetoresistance is observed in lightly boron-incorporated nanowire devices and it decreases with increase in boron content.

Magnetic Signature Of Symmetry Reduction In Epitaxial La₀.₆₇Sr₀.₃₃Mno₃ Films, Radhika Barua, L. H. Lewis, D. Heiman

Donald Heiman

The magnetic properties of epitaxially grown La0.67Sr0.33MnO3 perovskite thin films were investigated to elucidate an unexpected broken symmetry between orthogonal [100] and [010] inplane directions, resulting from the magnetostructural coupling between the film and the cubic SrTiO3 (001) substrate. The films were synthesized by molecular beam epitaxy with either complete or zero A-site cation disorder. Magnetization measured in [100] and [010] directions shows differences that signal a reduction of the in-plane cubic symmetry only for T < 290 K. The magnetization asymmetry is more robust in the film with complete A-site disorder. These results are attributed to a dominant Mn3+ character …

Universal Properties Of Linear Magnetoresistance In Strongly Disordered Mnas-Gaas Composite Semiconductors, H. Johnson, S. Bennett, R. Barua, L. Lewis, D. Heiman

Donald Heiman

Linear magnetoresistance (LMR) occurs in semiconductors as a consequence of strong electrical disorder and is characterized by nonsaturating magnetoresistance that is proportional to the applied magnetic field. By investigating a disordered MnAs-GaAs composite material, it is found that the magnitude of the LMR is numerically equal to the carrier mobility over a wide range and is independent of carrier density. This behavior is complementary to the Hall effect that is independent of the mobility and dependent on the carrier density. Moreover, the LMR appears to be insensitive to the details of the disorder and points to a universal explanation of …

Large Low Field Magnetoresistance In La₀.₆₇Sr₀.₃₃Mno₃ Nanowire Devices, Battogtokh Jugdersuren, Sungmu Kang, Robert S. Dipietro, Don Heiman, David Mckeown, Ian L. Pegg, John Philip

Donald Heiman

Large low field magnetoresistance (LFMR) of about 28% is observed in La0.67Sr0.33MnO3 nanowires with 80 nm in diameter at T = 300 K. A gradual decrease in the LFMR has been found with increase in wire diameter. The LFMR drops to zero for wires above 280 nm in diameter. The nanowires are grown by means of electrospinning process and exhibit distorted orthorhombic crystal structure. The large LFMR is considered as a grain boundary effect as observed in several perovskite systems. The large LFMR observed in these manganites with reduced dimensions may be useful for room temperature device applications.

Large Coercivity In Nanostructured Rare-Earth-Free Mnxga Films, Don Heiman, Tom Nummy, Steve Bennett, Tom Cardinal

Donald Heiman

The magnetic hysteresis of MnxGa films exhibit remarkably large coercive fields as high as HC=2.5 T when fabricated with nanoscale particles of a suitable size and orientation. This coercivity is an order of magnitude larger than in well-ordered epitaxial film counterparts and bulk materials. The enhanced coercivity is attributed to the combination of large magnetocrystalline anisotropy and ~50-100 nm size nanoparticles. The large coercivity is also replicated in the electrical properties through the anomalous Hall effect. The magnitude of the coercivity approaches that found in rare-earth magnets, making them attractive for rare-earth-free magnet applications.

Crystal Lattice Desolvation Effects On The Magnetic Quantum Tunneling Of Single-Molecule Magnets, G Redler, Christos Lampropoulos, S Datta, C Koo, T C. Stamatatos, N E. Chakov, G Christou, S Hill

Christos Lampropoulos

High-frequency electron paramagnetic resonance (HFEPR) and alternating current (ac) susceptibility measurements are reported for a new high-symmetry Mn12 complex, [Mn12O12(O2CCH3)16(CH3OH)4]⋅CH3OH. The results are compared to those of other high-symmetry spin S=10 Mn12 single-molecule magnets (SMMs), including the original acetate, [Mn12(O2CCH3)16(H2O)4]⋅2CH3CO2H⋅4H2O, and the [Mn12O12(O2CCH2Br)16(H2O)4]⋅4CH2Cl2 and [Mn12O12(O2CCH2But)16(CH3OH)4]⋅CH3OH complexes. These comparisons reveal important insights into the factors that influence the values of the effective barrier to magnetization reversal, Ueff, deduced on the basis of ac susceptibility measurements. In particular, we find that variations in Ueff can be correlated with the degree of disorder in a crystal which can be controlled by desolvating (drying) …

Spin Dynamics In Single-Molecule Magnets Combining Surface Acoustic Waves And High-Frequency Electron Paramagnetic Resonance, F Macià, J Lawrence, S Hill, J M. Hernandez, J Tejada, P V. Santos, Christos Lampropoulos, G Christou

Christos Lampropoulos

We report an experimental technique that integrates high-frequency surface acoustic waves (SAWs) with high-frequency electron paramagnetic resonance (HFEPR) spectroscopy in order to measure spin dynamics on fast time scales in single-molecule magnets. After the system is driven out of equilibrium by triggering magnetic avalanches, or simply by heating with short SAW pulses, the evolution of the spin populations within fixed energy levels is measured using HFEPR spectroscopy.

Alignment Of Magnetic Anisotropy Axes In Crystals Of Mn12 Acetate And Mn12-Tbuac Molecular Nanomagnets: Angle-Dependent Ac Susceptibility Study, E Burzurí, Ch Carbonera, F Luis, D Ruiz-Molina, Christos Lampropoulos, G Christou

Christos Lampropoulos

We report the results of angular-dependent ac susceptibility experiments performed on two derivatives of Mn12 single-molecular magnets: the well-known Mn12 acetate, which contains disordered acetic acid molecules in interstitial sites of the crystal structure and Mn12-tBuAc, for which solvent molecules are very well ordered in the structure. Our results show (a) that the angular variation is very similar in the two compounds investigated and compatible with a maximum misalignment of the anisotropy axes of less than 3° and (b) that the tunneling rate is faster for the better ordered Mn12-tBuAc compound. These experiments question interstitial disorder as the dominant origin …

Realization Of Random-Field Ising Ferromagnetism In A Molecular Magnet, Bo Wen, P Subedi, Lin Bo, Y Yeshurun, M P. Sarachik, A D. Kent, A J. Millis, Christos Lampropoulos, G Christou

Christos Lampropoulos

The longitudinal magnetic susceptibility of single crystals of the molecular magnet Mn12-acetate obeys a Curie-Weiss law, indicating a transition to a ferromagnetic phase at ∼0.9 K. With increasing magnetic field applied transverse to the easy axis, a marked change is observed in the temperature dependence of the susceptibility, and the suppression of ferromagnetism is considerably more rapid than predicted by mean-field theory for an ordered single crystal. Our results can instead be fit by a Hamiltonian for a random-field Ising ferromagnet in a transverse magnetic field, where the randomness derives from the intrinsic distribution of locally tilted magnetic easy axes …

Effects Of Quantum Mechanics On The Deflagration Threshold In The Molecular Magnet Mn12 Acetate, F Macià, J M. Hernandez, J Tejada, S Datta, S Hill, Christos Lampropoulos, G Christou

Christos Lampropoulos

We report experimental studies of the stability of a Mn12-Ac crystal against magnetic avalanches as a function of the magnitude and direction of the magnetic field, as well as a function of temperature. Strong evidence for quantum effects associated with this phenomenon is seen in the (Hz,Hx) metastability diagram. The data provide further support to the theory of magnetic deflagration.

Experimental Determination Of The Weiss Temperature Of Mn12-Ac And Mn12-Ac-Meoh, Christos Lampropoulos, Shiqi Li, Lin Bo, Bo Wen, M P. Sarachik, P Subedi, A D. Kent, Y Yeshurun, A J. Millis, S Mukherjee, G Christou

Christos Lampropoulos

We report measurements of the susceptibility in the temperature range from 3.5 to 6.0 K of a series of Mn12-ac and Mn12-ac-MeOH samples in the shape of rectangular prisms of length lc and square cross section of side la. The susceptibility obeys a Curie-Weiss law, χ=C/(T−θ), where θ varies systematically with sample aspect ratio. Using published demagnetization factors, we obtain θ for an infinitely long sample corresponding to intrinsic ordering temperatures Tc≈0.85 K and ≈0.74 K for Mn12-ac and Mn12-ac-MeOH, respectively. The difference in Tc for two materials that have nearly identical unit cell volumes and lattice constant ratios suggests …

Nonparametric Copula Density Estimation In Sensor Networks, Leming Qu, Hao Chen, Yicheng Tu

Leming Qu

Statistical and machine learning is a fundamental task in sensor networks. Real world data almost always exhibit dependence among different features. Copulas are full measures of statistical dependence among random variables. Estimating the underlying copula density function from distributed data is an important aspect of statistical learning in sensor networks. With limited communication capacities or privacy concerns, centralization of the data is often impossible. By only collecting the ranks of the data observed by different sensors, we estimate and evaluate the copula density on an equally spaced grid after binning the standardized ranks at the fusion center. Without assuming any …

Technology Enhanced Learning: Students' Views, Eileen O'Donnell, Mary Sharp

Eileen O'Donnell

User feedback is very important in all areas of computer science especially in the development of computer applications. Hence, student feedback on the use of technology enhanced learning in higher education in Ireland is relevant to the quality of the learning resources to be created by learning designers and academics in the future. The book “Student Reactions to Learning with Technologies: Perceptions and Outcomes” (Moyle & Wijngaards, 2012) was published by IGI Global in October 2011. This book includes contributions from various authors who are interested in students’ feedback regarding how technology has impacted on their educational experience. This book …

Absolute Quantification Of Gene Expression In Individual Bacterial Cells Using Two-Photon Fluctuation Microscopy, Matthew L. Ferguson, Dominique Le Coq, Matthieu Jules, Stéphane Aymerich, Nathalie Declerck, Catherine A. Royer

Matthew L. Ferguson

Quantification of promoter activity or protein expression in gene regulatory networks is generally achieved via measurement of fluorescent protein (FP) intensity, which is related to the true FP concentration by an unknown scaling factor, thereby limiting analysis and interpretation. Here, using approaches originally developed for eukaryotic cells, we show that two-photon (2p) fluorescence fluctuation microscopy, specifically scanning number and brightness (sN&B) analysis, can be applied to determine the absolute concentrations of diffusing FPs in live bacterial cells. First, we demonstrate the validity of the approach, despite the small size of the bacteria, using the central pixels and spatial averaging. We …

Its Training Update, Veronica Trammell

Veronica O. Trammell

No abstract provided.