Physical Sciences and Mathematics Commons^™

Wicked Tools: The Value Of Scientific Models For Solving Maine’S Wicked Problems, Tim Waring

Timothy M Waring

“Wicked problems” are urgent, high-stake socioeconomic-environmental challenges that often involve ideological conflict and have no “best solutions.” Using examples from Maine’s Sustainability Solutions Initiative projects, Tim Waring describes how scientific models can be used to address these kinds of problems. When well-constructed and tested models are used to address policy-relevant issues, include input from stakeholders, and integrate social, economic and environmental dynamics, they can become “wicked tools” to address some of society’s biggest challenges.

Crosslinked Polymer Sheaths For Dispersing Individual Single-Walled Carbon Nanotubes In Nonaqueous Solvents, L. Ojha, M. Tchoul, K. Bastola, K. Ausman

Kevin D. Ausman

Single-walled carbon nanotubes have been suspended individually in water by encasing them in a thin, uniform layer of the crosslinkable polymer poly (N-vinylpyrrolidone-co-allylamine). When this polymer is crosslinked under dilute conditions, the polymer sheath, formerly stabilized by the hydrophobic effect, becomes stable to changes in the solvent system.

Fibonacci And Lucas Identities Via Graphs, Joe Demaio, John Jacobson

Joe DeMaio

Big History: The Sun: Season 1 Episode 13, Mojgan Behmand

Mojgan Behmand

Simultaneous Redox Conversion Of Chromium(Vi) And Arsenic(Iii) Under Acidic Conditions, Zhaohui Wang, Richard Bush, Leigh Sullivan, Jianshe Liu

Dr Zhaohui Wang

Arsenic and chromium are often abundant constituents of acid mine drainage (AMD) and are most harmful as arsenite (As(III)) and hexavalent (Cr(VI)). To simultaneously change their oxidation state from As(III) to As(V), and Cr(VI) to Cr(III), is a potentially effective and attractive strategy for environmental remediation. The coabundance of As(III) and Cr(VI) in natural environments indicates their negligible direct interaction. The addition of H2O2enables and greatly accelerates the simultaneous oxidation of As(III) and reduction of Cr(VI). These reactions are further enhanced at acidic pH and higher concentrations of Cr(VI). However, the presence of ligands (i.e., oxalate, citrate, pyrophosphate) greatly retards …

Light Induced Structures In Liquid Crystalline Side-Chain Polymers With Azobenzene Functional Groups, O. Yaroschuk, Tatiana Sergan, J. Lindau, S. Lee, J. Kelly, Liang-Chy Chien

Liang-Chy Chien

We applied ellipsometry to study the distribution of azobenzene fragments in the films of two types of comblike polymers with azobenzene moieties in the side chains before and after ultraviolet ~UV! light irradiation. The polymer with an alkyl chain at the end of the azobenzene fragment forms structures with preferred homeotropic alignment of the fragments. Irradiation of this polymer with nonpolarized UV light at normal incidence induces a homeotropic alignment of azobenzene fragments. Oblique irradiation induces tilted structures. Polarized UV light irradiation at normal beam incidence induces biaxial structures with a fanlike distribution of azobenzene fragments and preferably out-of-plane alignment. …

Short Pitch Cholesteric Electro-Optical Device Stabilized By Nonuniform Polymer Network, Sang Kim, Liang-Chy Chien

Liang-Chy Chien

We have developed a method for stabilization of the uniform lying helix (ULH) texture of short pitch cholesterics in an electro-optical device, based on the flexoelectro-optic effect in such a texture. By using a small concentration of photoreactive liquid crystal monomer (less than 5 wt. %) and selecting the illumination conditions, we were able to create a nonuniform polymeric network in the liquid crystal bulk (localized essentially at both substrate surfaces) which stabilized efficiently the amplitude and the phase modulation modes of the device. Most importantly, the effect of the residual birefringence of the polymeric network in the field-unwound state …

Structure And Morphology Of Polymer-Stabilized Cholesteric Diffraction Gratings, Shin-Woong Kang, Samuel Sprunt, Liang-Chy Chien

Liang-Chy Chien

We report a study of polymer network morphology in planar diffraction gratings formed from polymer-stabilized cholesteric liquid crystals. Photopolymerizing a mesogenic monomer yields a regular sawtooth morphology, composed of polymer sheets running at an acute angle between thick, uniformly aligned bundles which reside on the opposing substrates. To explain this morphology and evidence of two grating vectors in the diffraction pattern, we propose a model for the liquid-crystal director where out-of-phase twists at the surfaces gear into an interior twist, which has half the period of the surface twist, via splay distortions running between the substrates. The morphology also changes …

Control Of Reflectivity And Bistability In Displays Using Cholesteric Liquid-Crystals, Deng-Ke Yang, John West, Liang-Chy Chien, J. Doane

Liang-Chy Chien

It is demonstrated that the reflective properties and bistability of cholesteric liquid crystals can be controlled by proper surface treatment and dispersed polymers. Dispersing a polymer in the liquid crystal or using a cell with an inhomogeneous surface anchoring creates permanent defects which result in long-term bistability, high contrast at large viewing angles, and gray scale. The wide-angle, reflective feature makes cholesteric materials suitable for displays without backlights and bistability provides flicker-free operation.

Field-Induced And Polymer-Stabilized Two-Dimensional Cholesteric Liquid Crystal Gratings, Shin-Woong Kang, Liang-Chy Chien

Liang-Chy Chien

The authors experimentally demonstrate an electrically switchable gratings based on polymer-stabilized, field-induced two-dimensional square-lattice pattern of a cholesteric liquid crystal. A dependence of the two-dimensional diffraction patterns with the magnitude of applied voltage is observed for before and after the polymer stabilization. The diffraction efficiency reaches 84% calculated for the zero order light intensity at the applied voltage of 0.23 V/mu m for a 10 mu m thick sample.

Dynamical Studies Of Gratings Formed In Polymer-Dispersed Liquid Crystal Films, Andy Fuh, T. Ko, M. Tsai, C. Huang, Liang-Chy Chien

Liang-Chy Chien

The use of polymer-dispersed liquid crystal films to fabricate gratings was demonstrated. The written gratings are permanent, but are electrically switchable. In this article, we report the results obtained from the dynamical studies of gratings formed in polymer-dispersed liquid crystal films having various liquid crystal-polymer mixing ratios. The results showed that during the initial phases of formation, a thermal grating effect dominated. Later, it was offset or quenched by the photopolymerization effect which eventually dominated and determined the characteristics of the final grating.

Photoinduced Three-Dimensional Orientational Order In Side Chain Liquid Crystalline Azopolymers, O. Yaroshchuk, K. Kiselev, Yu. Zakrevskyy, T. Bidna, J. Kelly, Liang-Chy Chien, J. Lindau

Liang-Chy Chien

We apply experimental technique based on the combination of methods dealing with principal refractive indices and absorption coefficients to study the photoinduced three-dimensional (3D) orientational order in the films of liquid crystalline (LC) azopolymers. The technique is used to identify 3D orientational configurations of trans azobenzene chromophores and to characterize the degree of ordering in terms of order parameters. We study two types of LC azopolymers which form structures with preferred in-plane and out-of-plane alignment of azochromophores, respectively. Using irradiation with the polarized light of two different wavelengths, we find that the kinetics of photoinduced anisotropy can be dominated by …

Nematic Director Orientation In A Liquid-Crystal-Dispersed Polymer - A Deuterium Nmr Approach, Ralf Stannarius, G. Crawford, Liang-Chy Chien, J. Doane

Liang-Chy Chien

The nuclear-magnetic-resonance (NMR) technique is employed to liquid-crystal-dispersed-polymer (LCDP) systems. Deuterium NMR is used to determine director distributions in LCDP cells in the presence of a magnetic field. The samples consist of a nematic liquid crystal mixed with small percentages of a monomer that is polymerized under different conditions after dissolving it in the liquid crystal. NMR spectra of the deuterated liquid-crystal molecules give information on orientation and order in such systems. The orientation of the polymer skeleton formed during the polymerization is found to be stable. It determines the orientation of the nematic director even in the presence of …

Municipal Solid Wastes And Water Quality Issues In Nigeria, S Isiorho, D Omole

S Isiorho

No abstract provided.

So You Measured Chemical Parameters In A Well Field And So What?, Sarah Budd, Tammy Lafaucia, S Isiorho

S Isiorho

No abstract provided.

A Multispacecraft Istp Study: Substorm Evolution From The Solar Wind To The Magnetosphere And Ionosphere, T Pulkkinen, D Baker, Niescja Turner, H Singer, J Blake, H Spence, L Frank, J Sigwarth, T Mukai, S Kokubun, R Nakamura, C Russell, H Kawano, F Mozer, J Slavin, R Lepping, R Anderson, G Reeves, L Zelenyi

Niescja E. Turner

An isolated substorm event on May 15, 1996, was recorded by an unprecedented suite of satellites both in the solar wind and in the magnetosphere. We show data from various instruments onboard several ISTP satellites to discuss both the prompt response of the dayside magnetosphere to the changes in the interplanetary magnetic field and the following substorm evolution in the nightside tail.

A Substorm Onset Observed By The Polar Spacecraft In Conjunction With The Image Chain, P Toivanen, D Baker, W Peterson, A Viljanen, Niescja Turner, X Li, C Kletzing

Niescja E. Turner

No abstract provided.

Reply To Comment On "Evaluation Of The Tail Current Contribution To Dst", Niescja Turner, D Baker, T Pulkkinen, R Mcpherron

Niescja E. Turner

Turner et al. [2000] analyzed the contribution of cross-tail currents to the Dst index. In order to estimate this contribution we used modified versions of the Tsyganenko models which had been adjusted to match spacecraft data in the tail, and we isolated a tail region and calculated its influence. We concluded that the tail currents were responsible for around 25% of the Dst response during moderately disturbed times. Maltsev and Ostapenko [2002] conclude that our estimate was low by a factor of 2, owing to that fact that we neglected dayside currents and that the model we used systematically underestimates …

Florida Energy Assurance Plan, Niescja Turner, W Murtagh, K Guthrie, K Nykyri, W Radasky, E Senkowicz

Niescja E. Turner

No abstract provided.

Reconciliation Of The Substorm Onset Determined On The Ground, In The Equatorial Magnetosphere, And At The Polar Spacecraft, P Toivanen, D Baker, W Peterson, H Singer, Niescja Turner, X Li, K Kauristie, M Syrjasuo, A Keiling, C Kletzing, C Russell

Niescja E. Turner

An isolated substorm on Oct. 17, 1997 during a close conjunction of the Polar spacecraft and the ground-based MIRACLE network is studied in detail. We identify signatures of substorm onset in the plasma sheet midway between the ionosphere and the equatorial plasma sheet, determine their timing relative to the ground signatures, and discuss their counterparts on the ground and in the equatorial plasma sheet. The substorm onset is determined as the negative bay onset at 2040:42(≠ 5 sec) UT coinciding with the onset of auroral precipitation, energization of plasma sheet electrons at Polar, and strong magnetic field variations perpendicular to …

The Magnetic Field Induced By A Lightning Strikes Indirect Effect Double Exponential Current Waveform, S Meredith, S Earles, I Kostanic, Niescja Turner

Niescja E. Turner

Problem statement: Develop a new formula which describes the magnetic field induced by a lightning strike's indirect effect double exponential current waveform. Approach: A novel approach for developing a closed-form solution for the magnetic field from the indirect effect double exponential current waveform will be presented. In the literature, models typically employ the pulse waveform to derive the corresponding electromagnetic fields. However, given the Department of Defense (DoD) has incorporated the double exponential current waveform as part of their "Electromagnetic Environmental Effects Requirements For Systems", we felt it important to develop a solution for the magnetic field which utilized this …

Evaluation Of The Tail Current Contribution To Dst, Niescja Turner, D Baker, T Pulkkinen, R Mcpherron

Niescja E. Turner

The Dst index is produced using low-latitude ground magnetic field measurements and frequently is used as an estimate of the energy density of the ring current carried mainly by energetic (∼10-200 keV) ions relatively close to the Earth. However, other magnetospheric current systems can cause field perturbations at the Earth's surface: for example, dayside magnetopause currents are known to contribute to the Dst index. It has also been suggested that the nightside tail current sheet can significantly affect the Dst index during high magnetic activity periods when the currents are intense and flow relatively close to the Earth. In this …

Geoeffectiveness Of Cir And Cme Events: Factors Contributing To Their Differences, L Laughlin, Niescja Turner

Niescja E. Turner

Recent work has shown that solar wind-magnetosphere coupling is moreefficient for CIR-driven events than for CME-driven events. The studyherein looks into the individual physical parameters of Corotating Interaction Regions (CIRs) and Coronal Mass Ejections (CMEs) and looks to isolate particular characteristics that leads to greater coupling ofenergy from the solar wind into the magnetosphere for certain classesof magnetic storms. While it is clear that these two types of events are distinct in their outcome, it is not known what in the nature of the events leads to these different results. The variation level in the z-component of the Interplanetary Magnetic …

Correlation Of Changes In The Outer-Zone Relativistic-Electron Population With Upstream Solar Wind Measurements, J Blake, D Baker, Niescja Turner, K Ogilvie, R Lepping

Niescja E. Turner

A study has been made of the correlation of the population of relativistic electrons in the outer-zone magnetosphere with the properties of the solar wind (speed, density, magnetic field) during a solar minimum period. The study is based upon observations made in the Spring of 1995 with sensors aboard 1994-026 and WIND. It is found that a large relativistic electron enhancement depends upon a substantial solar-wind speed increase associated with precursor solar-wind density enhancement, and, in particular, upon a southward turning of the interplanetary magnetic field

Ring Current Ion Composition During Solar Minimum And Rising Solar Activity: Polar/Cammice/Mics Results, T Pulkkinen, N Ganushkina, D Baker, Niescja Turner, J Fennell, J Roeder, T Fritz, M Grande, B Kellett, G Kettmann

Niescja E. Turner

This paper shows statistical results of the ring current ion composition and its variability as a function of solar cycle and magnetospheric activity for 3 < L < 8. Spin-averaged energetic particle (1-200 keV) measurements from Polar are combined with geomagnetic indices as well as solar wind and interplanetary observations from the Wind spacecraft during a period from September 1996 to March 1999. The statistics are performed both for time-averaged values for all periods as well as for peak flux values during geomagnetic storms (defined as Dst < -50 nT) that occurred during this period. The average O+ energy density increases by about …

Energy Content Of The Stormtime Ring Current, Niescja Turner, D Baker, T Pulkkinen, J Roeder, J Fennell, V Jordanova

Niescja E. Turner

Given the important role the ring current plays in magnetospheric energetics, it is essential to understand its strength and evolution in disturbed times. There are currently three main methods for deducing the strength of the ring current: measuring ground magnetic perturbations, measuring high-altitude magnetic perturbations, or directly measuring ring current particles. The use of ground magnetometers is the most convenient, and many use the ground magnetometer-derived Dst index as a proxy for the ring current. Recent work suggests, however, that a substantial portion of Dst may not be caused only by the ring current but also by local induction effects …

How Lightning Tortuosity Affects The Electromagnetic Fields By Augmenting Their Effective Distance, S Meredith, S Earles, I Kostanic, Niescja Turner, C Otero

Niescja E. Turner

A novel approach for developing the electromagnetic fields from a lightning return stroke which follows a tortuous path will be presented. The proposed model is unique in that it recognizes that the symmetrical tortuosity of lightning directly impacts the observable distance r, which in turn, alters the resulting electromagnetic fields. In the literature, lightning return stroke models typically employ the assumption that the cloud-to-ground path is straight. Although this assumption yields fairly consistent results across an array of varying approaches, it does not account for lightning's natural physical appearance. Furthermore, straight-line models only account for the cloud-to-ground discharges and do …

High-Altitude Polar Cap Electric Field Responses To Southward Turnings Of The Interplanetary Magnetic Field, Niescja Turner, D Baker, T Pulkkinen, H Singer, F Mozer, R Lepping

Niescja E. Turner

Interplanetary electric field coupling with the magnetosphere has been analyzed predominantly using data from the Wind magnetometer and the Polar electric field instrument. The coupling was investigated using the Polar Electric Field Instrument (EFI) to measure the electric field in the northern polar cap immediately following sharp southward turnings of the IMF as observed by Wind. Southward turnings were chosen which exhibited a sudden change of the IMF north-south component from BZ > 0 to BZ < 0 (GSM coordinates) after an hour or more of relatively stable conditions, and for which Polar was in the northern polar cap. These BZ changes …

Neuro-Fuzzy Admission Control In Cellular Networks, Raad Raad, Ibrahim Raad

Dr Raad Raad

In this paper, a methodology is presented for designing an adaptive fuzzy logic controller based on neural networks. The neuro-fuzzy controller is first trained using data from an approximate analytical model of a cellular network then the controller is fine tuned and adapted to the unique cell dwell time and call holding time distributions of a particular cell in the network. Different cell dwell time distributions are considered for training the neuro-fuzzy controller. A neuro-fuzzy method that only relies on a limited amount of measured data for training purposes is also presented.

Air Blasting As The Optimal Approach For The Extraction Of Antioxidants In Coral Tissue, Elisabeth Deschaseaux, Myrna Deseo, Kellie Shepherd, Graham Jones, Peter Harrison

Dr Myrna A Deseo

In order to accurately measure the antioxidant capacity in corals, it is essential to optimally extract antioxidants from coral tissue. Here, we compared the two most commonly used methods for coral tissue extraction, air blasting (similar to Water-Pik method) and grinding, with or without sonication, to optimally extract antioxidants in corals. By air blasting, the coral tissue was stripped off the skeleton with a stream of compressed air into a polyethylene bag containing a known volume of buffer, whereas by grinding, both the coral tissue and skeleton were crushed using a mortar and pestle into a powder and homogenised in …