Why is the ground state electron configuration for Lithium 1s22s1s^22s ?

The electronic ground state for Lithium is $1s^22s$, and not $1s^22p$. The traditional argument for why this is so is based on a screening argument that claims that the $2p$ electron is better shielded by the $1s$ electrons, and therefore higher in energy then the configuration that includes the $2s$ electron. We show that this argument is flawed, and in fact the actual reason for the ordering is because the electron-electron interaction energy is higher for the $2p-1s$ repulsion than it is for the $2s-1s$ repulsion.Comment: 4 page

Computers, the internet, and cheating among secondary school students: Some implications for educators

This article investigates in greater depth one particular aspect of cheating within secondary education and some implications for measuring academic achievement. More specifically, it examines how secondary students exploit the Internet for plagiarizing schoolwork, and looks at how a traditional method of educational assessment, namely paper-based report and essay writing, has been impacted by the growth of Internet usage and the proliferation of computer skills among secondary school students. One of the conclusions is that students’ technology fluency is forcing educators to revisit conventional assessment methods. Different options for combating Internet plagiarism are presented, and some software tools as well as non-technology solutions are evaluated in light of the problems brought about by “cyberplagiarism.

Understanding the performance of the low energy neutrino factory: the dependence on baseline distance and stored-muon energy

Motivated by recent hints of large {\theta}13 from the T2K, MINOS and Double Chooz experiments, we study the physics reach of a Low Energy Neutrino Factory (LENF) and its dependence on the chosen baseline distance, L, and stored-muon energy, E_{\mu}, in order to ascertain the configuration of the optimal LENF. In particular, we study the performance of the LENF over a range of baseline distances from 1000 km to 4000 km and stored-muon energies from 4 GeV to 25 GeV, connecting the early studies of the LENF (1300 km, 4.5 GeV) to those of the conventional, high-energy neutrino factory design (4000 km and 7000 km, 25 GeV). Three different magnetized detector options are considered: a Totally-Active Scintillator Detector (TASD) and two models of a liquid-argon detector distinguished by optimistic and conservative performance estimates. In order to compare the sensitivity of each set-up, we compute the full {\delta}-dependent discovery contours for the determination of non-zero {\theta}13, CP-violating values of {\delta} and the mass hierarchy. In the case of large {\theta}13 with sin^2(2*{\theta}13) = (few)*10^{-3}, the LENF provides a strong discovery potential over the majority of the L-E_{\mu} parameter space and is a promising candidate for the future generation of long baseline experiments aimed at discovering CP-violation and the mass hierarchy, and at making a precise determination of the oscillation parameters.Comment: 14 pages, 5 figure

The Leadership Gap: What Gets Between You and Your Greatness

A review of The Leadership Gap: What Gets Between You and Your Greatness, by Lolly Daskal

Marketing Rebellion: The Most Human Company Wins

A review of Marketing Rebellion: The Most Human Company Wins, by Mark Schaefer

Intrinsic noise induced resonance in presence of sub-threshold signal in Brusselator

In a system of non-linear chemical reactions called the Brusselator, we show that {\it intrinsic noise} can be regulated to drive it to exhibit resonance in the presence of a sub-threshold signal. The phenomena of periodic stochastic resonance and aperiodic stochastic resonance, hitherto studied mostly with extrinsic noise, is demonstrated here to occur with inherent systemic noise using exact stochastic simulation algorithm due to Gillespie. The role of intrinsic noise in a couple of other phenomena is also discussed.Comment: 7 pages, 5 figure

Electrochemical evaluation of corrosion resistance of chromium plated nickel and copper tin alloys. A comparative study

Engineering materials and composites are frequently exposed to aggressive and chemically toxic environments with high probability for rapid corrosion and consequent deterioration and catastrophic degradation. Occasionally, a new legislation regulates against the use of existing materials, necessitating thus development of new methodologies or new materials in order to reduce material corrosion rates. The aim of this study is to test the corrosion resistance of the copper tin alloy, a material that could replace nickel compounds, recently reclassified as suspected carcinogens. Standard sizes of pre-cut nickel and brass panels were produced and then plated with different thicknesses of copper tin alloy and chromium for additional protection. Evaluation of plated materials for corrosion rate and resistance was carried out using linear polarisation, electrochemical impedance and accelerated destructive testing. Corrosion testing of the materials assessed qualitatively and quantitatively, showed that corrosion resistance was dependent on a combination of factors, including the thickness of chromium plating, type of material, type of testing and duration in a corrosion chamber. While linear polarisation experiment was useful in establishing corrosion rate of sample, electrochemical impedance and accelerated destructive testing experiments assessed corrosion resistance of the materials

The Gravitomagnetic Influence on Gyroscopes and on the Lunar Orbit

Gravitomagnetism--a motional coupling of matter analogous to the Lorentz force in electromagnetism--has observable consequences for any scenario involving differing mass currents. Examples include gyroscopes located near a rotating massive body, and the interaction of two orbiting bodies. In the former case, the resulting precession of the gyroscope is often called ``frame dragging,'' and is the principal measurement sought by the Gravity Probe-B experiment. The latter case is realized in the earth-moon system, and the effect has in fact been confirmed via lunar laser ranging (LLR) to approximately 0.1% accuracy--better than the anticipated accuracy of the Gravity-Probe-B result. This paper shows the connnection between these seemingly disparate phenomena by employing the same gravitomagnetic term in the equation of motion to obtain both gyroscopic precession and modification of the lunar orbit. Since lunar ranging currently provides a part in a thousand fit to the gravitomagnetic contributions to the lunar orbit, this feature of post-Newtonian gravity is not adjustable to fit any anomalous result beyond the 0.1% level from Gravity Probe-B without disturbing the existing fit of theory to the 36 years of LLR data.Comment: 4 pages; accepted for publication in Physical Review Letter

Potential formulation of the dispersion relation for a uniform, magnetized plasma with stationary ions in terms of a vector phasor

The derivation of the helicon dispersion relation for a uniform plasma with stationary ions subject to a constant background magnetic field is reexamined in terms of the potential formulation of electrodynamics. Under the same conditions considered by the standard derivation, the nonlinear self-coupling between the perturbed electron flow and the potential it generates is addressed. The plane wave solution for general propagation vector is determined for all frequencies and expressed in terms of a vector phasor. The behavior of the solution as described in vacuum units depends upon the ratio of conductivity to the magnitude of the background field. Only at low conductivity and below the cyclotron frequency can significant propagation occur as determined by the ratio of skin depth to wavelength.Comment: 10 pages, 6 figures, major revision, final version, to appear in Po