Study Of The Numerical Modeling Of The Temperature Dependence Of The Dark Current In Charge Coupled Devices, 2010 Portland State University

#### Study Of The Numerical Modeling Of The Temperature Dependence Of The Dark Current In Charge Coupled Devices, Ralf Widenhorn, Ionel Tunaru, Erik Bodegom, Dan A. Iordache

*Physics Faculty Publications and Presentations*

As it is well known, the classical works of the Dark Current Spectroscopy method allow - using some not too accurate theoretical relations, but huge numbers of dark current values for thousands of pixels - the evaluation of a reduced number of basic impurities parameters. Unlike these works, this paper tries to obtain--by means of some better approximations of the Shockley-Read-Hall (SRH) model--more information about the studied impurities, as well as the study of the compatibility of the used theoretical model SRH relative to the experimental data. In this manner, both the compatibility SRH model with the studied experimental data was checked ...

Using Python To Program Lego Mindstorms Robots: The Pynxc Project, 2010 Bryant University

#### Using Python To Program Lego Mindstorms Robots: The Pynxc Project, Brian S. Blais

*Science and Technology Faculty Journal Articles*

LEGO MINDSTORMS® NXT (Lego Group, 2006) is a perfect platform for introducing programming concepts, and is generally targeted toward children from age 8-14. The language which ships with the MINDSTORMS®, called NXTg, is a graphical language based on LabVIEW (Jeff Kodosky, 2010). Although there is much value in graphical languages, such as LabVIEW, a text-based alternative can be targeted at an older audiences and serve as part of a more general introduction to modern computing. Other languages, such as NXC (Not Exactly C) (Hansen, 2010) and PbLua (Hempel, 2010), fit this description. Here we introduce PyNXC, a subset of the ...

Picosecond Electron Diffraction From Molecules Aligned By Dissociation, 2010 University of Nebraska - Lincoln

#### Picosecond Electron Diffraction From Molecules Aligned By Dissociation, Martin Centurion, Peter Reckenthaeler, Ferenc Krausz, Ernst E. Fill

*Martin Centurion Publications*

In gas electron diffraction an averaging over statistical directions of the molecules takes place. This results in diffraction patterns in the form of isotropic rings which yield information only on the radial distribution function displaying the inter-atomic distances. We demonstrate that by dissociating molecules with linearly polarized light the pattern becomes anisotropic. In the experiments the iodide C_{2}F_{4}I_{2} is dissociated and molecular difference intensities and difference radial distribution curves are measured for directions parallel and perpendicular to the direction of polarization. With picosecond temporal resolution the curves clearly demonstrate transient anisotropy and its decay by ...

A Two-Dimensional, Linear–Elastic Model To Explain Radial Extensional Fractures, Pantheon Fossae, Caloris Basin, Mercury, 2010 Bridgewater State University

#### A Two-Dimensional, Linear–Elastic Model To Explain Radial Extensional Fractures, Pantheon Fossae, Caloris Basin, Mercury, Brianne Mcdonough

*Undergraduate Review*

In this study, two-dimensional linear elasticity theory is used to model the lithospheric stress field that produces radial extensional fractures observed at Pantheon Fossae in the Caloris Basin of Mercury. These fractures were imaged by the MESSENGER mission flyby of Mercury on January 14, 2008 and show radial fractures extending outward from a 40-kilometer impact crater named Apollodorus. Recent studies have proposed several different mechanisms to explain these fractures, including magmatic processes, central basin uplift, and stresses produced by the formation of the impact crater itself.

A New Technique For Firn Grain-Size Measurement Using Sem Image Analysis, 2010 University of Maine

#### A New Technique For Firn Grain-Size Measurement Using Sem Image Analysis, N.E. Spaulding, D.A. Meese, I. Baker, P.A. Mayewski

*Dartmouth Scholarship*

Firn microstructure is accurately characterized using images obtained from scanning electron microscopy (SEM). Visibly etched grain boundaries within images are used to create a skeleton outline of the microstructure. A pixel-counting utility is applied to the outline to determine grain area. Firn grain sizes calculated using the technique described here are compared to those calculated using the techniques of Gow (1969) and Gay and Weiss (1999) on samples of the same material, and are found to be substantially smaller. The differences in grain size between the techniques are attributed to sampling deficiencies (e.g. the inclusion of pore filler in ...

Gauge Non-Invariance As Tests Of Emergent Gauge Symmetry, 2010 University of Massachusetts Amherst

#### Gauge Non-Invariance As Tests Of Emergent Gauge Symmetry, John Donoghue, Mohamed M. Anber, Ufuk Aydemir

*Physics Department Faculty Publication Series*

We motivate the concept of emergent gauge symmetry and discuss ways that this concept can be tested. The key idea is that if a symmetry is emergent, one should look for small violations of this symmetry because the underlying fundamental theory does not contain the symmetry. We describe our recent work implementing this idea in the gravity sector. We also describe the reasons why violations of gauge symmetry may well be linked to violations of Lorentz invariance.

Equivalence Principle Violations And Couplings Of A Light Dilaton, 2010 University of Massachusetts Amherst

#### Equivalence Principle Violations And Couplings Of A Light Dilaton, John Donoghue, Thibault Damour

*Physics Department Faculty Publication Series*

We consider possible violations of the equivalence principle through the exchange of a light “dilaton-like” scalar field. Using recent work on the quark-mass dependence of nuclear binding, we find that the dilaton-quark-mass coupling induces significant equivalence-principle-violating effects varying like the inverse cubic root of the atomic number—A-1/3. We provide a general parametrization of the scalar couplings, but argue that two parameters are likely to dominate the equivalence-principle phenomenology. We indicate the implications of this framework for comparing the sensitivities of current and planned experimental tests of the equivalence principle.

Beyond Spontaneously Broken Symmetry In Bose-Einstein Condensates, 2010 University of Massachusetts - Amherst

#### Beyond Spontaneously Broken Symmetry In Bose-Einstein Condensates, Wj Mullin, F Laloe

*Physics Department Faculty Publication Series*

Spontaneous symmetry breaking (SSB) for Bose-Einstein condensates cannot treat phase off-diagonal effects, and thus cannot explain Bell inequality violations. We describe another situation that is beyond a SSB treatment: an experiment where particles from two (possibly macroscopic) condensate sources are used for conjugate measurements of the relative phase and populations. Off-diagonal phase effects are characterized by a “quantum angle” and observed via “population oscillations,” signaling quantum interference of macroscopically distinct states.

Classical Phases And Quantum Angles In The Description Of Interfering Bose-Einstein Condensates, 2010 University of Massachusetts - Amherst

#### Classical Phases And Quantum Angles In The Description Of Interfering Bose-Einstein Condensates, Wj Mullin, F Laloe

*Physics Department Faculty Publication Series*

The interference of two Bose-Einstein condensates, initially in Fock states, can be described in terms of their relative phase, treated as a random unknown variable. This phase can be understood either as emerging from the measurements or pre-existing to them; in the latter case, the originating states could be phase states with unknown phases, so an average over all their possible values is taken. Both points of view lead to a description of probabilities of results of experiments in terms of a phase angle, which plays the role of a classical variable. Nevertheless, in some situations, this description is not ...

Phenomenology Of The Equivalence Principle With Light Scalars, 2010 University of Massachusetts Amherst

#### Phenomenology Of The Equivalence Principle With Light Scalars, T Damour, Jf Donoghue

*Physics Department Faculty Publication Series*

Light scalar particles with couplings of sub-gravitational strength, which can generically be called 'dilatons', can produce violations of the equivalence principle. However, in order to understand experimental sensitivities one must know the coupling of these scalars to atomic systems. We report here on a study of the required couplings. We give a general Lagrangian with five independent dilaton parameters and calculate the 'dilaton charge' of atomic systems for each of these. Two combinations are particularly important. One is due to the variations in the nuclear binding energy, with a sensitivity scaling with the atomic number as A−1/3. The ...

Likely Values Of The Higgs Vacuum Expectation Value, 2010 University of Massachusetts Amherst

#### Likely Values Of The Higgs Vacuum Expectation Value, Jf Donoghue, K Dutta, A Ross, M Tegmark

*Physics Department Faculty Publication Series*

We make an estimate of the likelihood function for the Higgs vacuum expectation value (vev) by imposing anthropic constraints on the existence of atoms while allowing the other parameters of the standard model to also be variable. We argue that the most important extra ingredients are the Yukawa couplings, and for the intrinsic distribution of Yukawa couplings we use the scale-invariant distribution which is favored phenomenologically. The result is successful phenomenologically, favoring values close to the observed vev. We also discuss modifications that can change these conclusions. Our work supports the hypothesis that the anthropic constraints could be the origin ...

Breaking Diffeomorphism Invariance And Tests For The Emergence Of Gravity, 2010 University of Massachusetts Amherst

#### Breaking Diffeomorphism Invariance And Tests For The Emergence Of Gravity, Mm Anber, U Aydemir, Jf Donoghue

*Physics Department Faculty Publication Series*

If general relativity is an emergent phenomenon, there may be small violations of diffeomorphism invariance. We propose a phenomenology of perturbatively small violations of general relativity by the inclusion of terms which break general covariance. These can be tested by matching to the Parameterized Post Newtonian (PPN) formalism. The most sensitive tests involve pulsar timing and provide an extremely strong bound, with a dimensionless constraint of order 10−20 relative to gravitational strength.

Calculating The Time Constant Of An Rc Circuit, 2010 University of South Florida

#### Calculating The Time Constant Of An Rc Circuit, Sean Dunford

*Undergraduate Journal of Mathematical Modeling: One + Two*

In this experiment, a capacitor was charged to its full capacitance then discharged through a resistor. By timing how long it took the capacitor to fully discharge through the resistor, we can determine the RC time constant using calculus.

Canal Lock Displacement, 2010 University of South Florida

#### Canal Lock Displacement, Rick Blanton

*Undergraduate Journal of Mathematical Modeling: One + Two*

In this project we determine the time needed for a pump to raise the water level in a canal lock in order for a boat to continue upstream. Using calculus methods and elementary physics, it was determined that it would take roughly 5 minutes for a single 60 horsepower pump to raise the water level the required 10 feet. We conclude that the lock is fairly efficient but offer some suggestions to increase the time efficiency of the lock system.

Automated Determination Of A Package's Center Of Mass, 2010 University of South Florida

#### Automated Determination Of A Package's Center Of Mass, Ayaz Hemani

*Undergraduate Journal of Mathematical Modeling: One + Two*

In order to address the issue of increased efficiency and better planning for parcel shipments, an automated computer program was developed in Microsoft Excel that calculates center of mass and moments of mass with greater speed and reliability than currently implemented systems. This simple program requires only a variable density function and limits of integration for a given object as input within the spreadsheet system. Once the required input has been provided, a series of chain calculations, with the help of a Visual Basic for Applications (VBA) script, is able to process the input, which is done through integration and ...

The Progression Of Sequential Reactions, 2010 University of South Florida

#### The Progression Of Sequential Reactions, Jack Mcgeachy

*Undergraduate Journal of Mathematical Modeling: One + Two*

Sequential reactions consist of linked reactions in which the product of the first reaction becomes the substrate of a second reaction. Sequential reactions occur in industrially important processes, such as the chlorination of methane. A generalized series of three sequential reactions was analyzed in order to determine the times at which each chemical species reaches its maximum. To determine the concentration of each species as a function of time, the differential rate laws for each species were solved. The solution of each gave the concentration curve of the chemical species. The concentration curves of species A_{1} and A_{2 ...}

Effect Of Tire Pressure On Efficiency, 2010 University of South Florida

#### Effect Of Tire Pressure On Efficiency, Miles Mullins

*Undergraduate Journal of Mathematical Modeling: One + Two*

Many people ignore tire pressure in their day-to-day lives. In a country striving for maximum efficiency, neglecting to maintain correct tire pressure can noticeably affect the amount of horsepower required to overcome the drag forces due to tire/roadway friction. In order to quantify these horsepower changes, 21 test trials were conducted by allowing a test vehicle to coast from 50 mph down to 20 mph at pressures ranging from 50 psi to 20 psi. After compiling the results, it was shown that lower tire pressures increased the horsepower necessary to propel the automobile.

Radiographic Imagery Of A Variable Density 3d Object, 2010 University of South Florida

#### Radiographic Imagery Of A Variable Density 3d Object, Justin Stottlemyer

*Undergraduate Journal of Mathematical Modeling: One + Two*

The purpose of this project is to develop a mathematical model to study 4D (three spatial dimensions plus density) shapes using 3D projections. In the model, the projection is represented as a function that can be applied to data produced by a radiation detector. The projection is visualized as a three-dimensional graph where x and y coordinates represent position and the z coordinate corresponds to the object's density and thickness. Contour plots of such 3D graphs can be used to construct traditional 2D radiographic images.

Brazilian Pepper's Impact On Barrier Island Biodiversity, 2010 University of South Florida

#### Brazilian Pepper's Impact On Barrier Island Biodiversity, Grayson Mccormick

*Undergraduate Journal of Mathematical Modeling: One + Two*

The Brazilian pepper is an invasive plant responsible for destruction of habitats of species native to Florida. We attempted to measure the impact of the Brazilian pepper on native plants by studying how it affects the biodiversity of Honeymoon Island, one of Florida's barrier islands. For this purpose we determined the population sizes of the Brazilian pepper along with five other species of plants on two quadrats of land laid out in Honeymoon Island State Park. Both Simpson's Index of Diversity and Shannon-Wiener Index were used to estimate the biodiversity and assess the impact of the Brazilian pepper ...

Population Dynamics Of Free-Roaming Cats In Florida's Lee County, 2010 University of South Florida

#### Population Dynamics Of Free-Roaming Cats In Florida's Lee County, Benjamin Taylor

*Undergraduate Journal of Mathematical Modeling: One + Two*

We investigate whether the Trap-Neuter-Return (TNR) program can be effectively used to control the population of free-roaming cats in Florida's Lee County. We do this by estimating the number of cats that must be spayed/neutered in order to keep the population from increasing.