Introduction to Security for Computer Architecture Students

Supplementary material for a graduate computer architecture class (4824) at Columbia

Active nematics on a substrate: giant number fluctuations and long-time tails

We construct the equations of motion for the coupled dynamics of order parameter and concentration for the nematic phase of driven particles on a solid surface, and show that they imply (i) giant number fluctuations, with a standard deviation proportional to the mean and (ii) long-time tails $\sim t^{-d/2}$ in the autocorrelation of the particle velocities in $d$ dimensions despite the absence of a hydrodynamic velocity field. Our predictions can be tested in experiments on aggregates of amoeboid cells as well as on layers of agitated granular matter.Comment: Submitted to Europhys Lett 26 Aug 200

Bromo-butyl Rubber for Face Piece of a Respiratory Mask

Respiratory mask contains a number of components made of materials like rubber, plastics, and metals. Out of all the components, face piece is the main component exposed to the external environment. This study aims to evaluate degradation of bromo-butyl rubber. The experiments were carried out for thermal exposure, swelling study, saline exposure, etc. It is observed that the elongation at break was increased by 10 per cent when these were exposed to 100 oC. However, the tensile strength has been observed to decrease by 50 per cent when exposed to 55 oC. It is decreased to around 63 per cent when exposed to 80 oC and 100 oC. The morphological appearance of unaged sample was intact. Only samples at 120 oC aged for 48 h appeared to have developed minor cracks of <0.01 µm. There were no significant changes observed when the samples were exposed to saline (3 % NaCl) and artificial sweat solution.Defence Science Journal, 2009, 59(5), pp.505-511, DOI:http://dx.doi.org/10.14429/dsj.59.155

A New Doctrine for Hardware Security

In recent years, high-profile hardware attacks have brought attention to the importance of and inadequate state of hardware security. Hardware security remains an elusive challenge because like other areas of security, it is an abnormal good where the economic laws of the free market fail to produce optimal outcomes. Correcting such marketplace failures is generally the role of government or other regulatory agencies and has been proposed and even implemented in some areas of security. However, little if no comparable work has been done in the realm of computer hardware. One explanation for this is that unlike other areas of security, we lack a comprehensive intellectual framework for discussing and reasoning about hardware security. We find that previous doctrines of security either do not apply or offer an incomplete perspective in this domain. We propose a new doctrine of hardware security based on the idea that achieving security is a burden, and that this burden must be shared between all the players in the game of security. Our doctrine serves as a tool for conceptualizing and understanding how hardware security should be regulated and administered

A Dynamic Renormalization Group Study of Active Nematics

We carry out a systematic construction of the coarse-grained dynamical equation of motion for the orientational order parameter for a two-dimensional active nematic, that is a nonequilibrium steady state with uniaxial, apolar orientational order. Using the dynamical renormalization group, we show that the leading nonlinearities in this equation are marginally \textit{irrelevant}. We discover a special limit of parameters in which the equation of motion for the angle field of bears a close relation to the 2d stochastic Burgers equation. We find nevertheless that, unlike for the Burgers problem, the nonlinearity is marginally irrelevant even in this special limit, as a result of of a hidden fluctuation-dissipation relation. 2d active nematics therefore have quasi-long-range order, just like their equilibrium counterpartsComment: 31 pages 6 figure

MANAGEMENT INFORMATION SYSTEM: FEW TIPS BEFITTING SMALL BUSINESSES TO AVERT ID THEFT CRITICAL OF ILLICIT TECHNOLOGY

Carrying large sums of money everywhere has long been seen cumbersome and provocative practice to criminals. Later this practice was viewed unprofessional within business and corporate practice and was thus replaced by cheques and lately by bank cards loosely referred to as plastic money. Despite all, one-man small businesses should also use a cheque to withdraw money from their current bank accounts like macro businesses; it still makes a lot of real sense when they use bank cards just for a start for their cash withdrawals. Given these, all entrepreneurial efforts taken when establishing these businesses to avoid legal and financial risks, there is still much out there to look out for to protect their cash when effecting deposits and withdrawals using black stripped bank cards. These entrepreneurial management strategies are tailor-made to help small firms which have just been established as they have not as yet fully established themselves evade ID theft. In order to achieve to avert this kind of crime, this paper will then provide few tips as management strategies befitting small firms to rather circumvent the said crime. This paper also takes cognisance of what the South African (SA) law actually says to protect small firms from this particular financial risk brought about by this crime

Constraints on neutrino masses from WMAP5 and BBN in the lepton asymmetric universe

In this paper, we put constraints on neutrino properties such as mass $m_{\nu}$ and degeneracy parameters $\xi_i$ from WMAP5 data and light element abundances by using a Markov chain Monte Carlo (MCMC) approach. In order to take consistently into account the effects of the degeneracy parameters, we run the Big Bang Nucleosynthesis code for each value of $\xi_i$ and the other cosmological parameters to estimate the Helium abundance, which is then used to calculate CMB anisotropy spectra instead of treating it as a free parameter. We find that the constraint on $m_{\nu}$ is fairly robust and does not vary very much even if the lepton asymmetry is allowed, and is given by $\sum m_\nu < 1.3 \rm eV$ ($95$).Comment: 19 pages, 7 figures, 5 table

The pressure-volume-temperature relationship of cellulose

Pressure–volume–temperature (PVT) mea- surements of a-cellulose with different water contents, were performed at temperatures from 25 to 180 °C and pressures from 19.6 to 196 MPa. PVT measurements allowed observation of the combined effects of pressure and temperature on the specific volume during cellulose thermo-compression. All isobars showed a decrease in cellulose specific volume with temperature. This densification is associated with a transition process of the cellulose, occurring at a temperature defined by the inflection point Tt of the isobar curve. Tt decreases from 110 to 40 °C with pressure and is lower as moisture content increases. For isobars obtained at high pressures and high moisture contents, after attaining a minimum, an increase in volume is observed with temperature that may be related to free water evaporation. PVT a-cellulose experimental data was compared with predicted values from a regression analysis of the Tait equations of state, usually applied to synthetic polymers. Good correla- tions were observed at low temperatures and low pressures. The densification observed from the PVT experimental data, at a temperature that decreases with pressure, could result from a sintering phenomenon, but more research is needed to actually understand the cohesion mechanism under these conditions