The use of Kodak aerochrome infrared color film, type 2443, as a remote sensing tool

An infrared color film, Kodak Aerochrome, type 2443, has replaced the 8443 film. The 2443 has lower contrast than the 8443 film, and allows deeper probing into areas that appear as solid black shadows on the 8443 film. The cyan layer of 2443 is approximately 1 1/2 stops slower, at a density of 1.4, than the yellow and magenta emulsion layers

Ion yields and erosion rates for Si1−xGex(0x1) ultralow energy O2+ secondary ion mass spectrometry in the energy range of 0.25–1 keV

We report the SIMS parameters required for the quantitative analysis of Si1−xGex across the range of 0 ≤ x ≤ 1 when using low energy O2+ primary ions at normal incidence. These include the silicon and germanium secondary ion yield [i.e., the measured ion signal (ions/s)] and erosion rate [i.e., the speed at which the material sputters (nm/min)] as a function of x. We show that the ratio Rx of erosion rates, Si1−xGex/Si, at a given x is almost independent of beam energy, implying that the properties of the altered layer are dominated by the interaction of oxygen with silicon. Rx shows an exponential dependence on x. Unsurprisingly, the silicon and germanium secondary ion yields are found to depart somewhat from proportionality to (1−x) and x, respectively, although an approximate linear relationship could be used for quantification across around 30% of the range of x (i.e., a reference material containing Ge fraction x would give reasonably accurate quantification across the range of ±0.15x). Direct comparison of the useful (ion) yields [i.e., the ratio of ion yield to the total number of atoms sputtered for a particular species (ions/atom)] and the sputter yields [i.e., the total number of atoms sputtered per incident primary ion (atoms/ions)] reveals a moderate matrix effect where the former decrease monotonically with increasing x except at the lowest beam energy investigated (250 eV). Here, the useful yield of Ge is found to be invariant with x. At 250 eV, the germanium ion and sputter yields are proportional to x for all x

Recovery of continuous wave squeezing at low frequencies

We propose and demonstrate a system that produces squeezed vacuum using a pair of optical parametric amplifiers. This scheme allows the production of phase sidebands on the squeezed vacuum which facilitate phase locking in downstream applications. We observe strong, stably locked, continuous wave vacuum squeezing at frequencies as low as 220 kHz. We propose an alternative resonator configuration to overcome low frequency squeezing degradation caused by the optical parametric amplifiers.Comment: 9 pages, 4 figure

What Can a Farmer Afford to Pay for Feeder Pigs?

Exact date of working paper unknown

Estigma sem sanções: A (falta de) impacto dos vales de escolares (voucher) para escolas particulares no desempenho dos alunos.

Under the Florida A+ Accountability Program, Florida’s schools are graded based on student performance on the Florida Comprehensive Assessment Test. Previously, when schools would earn their second failing grade within four years, students assigned to these schools were offered school vouchers which parents and guardians could use to transfer students to a private or another traditional public school. In January of 2006 the Florida Supreme Court declared that private school voucher component of the Florida A+ Accountability Program was unconstitutional, eliminating the threat of having these students and funds leaving to attend private schools. This exogenous shock allows us to test whether private voucher threats and the funding tied to these students led to increases in student achievement. We find no evidence that the private school voucher threats drive academic improvement beyond what is seen in schools when this private school voucher threat is removed.En el marco del Programa de Evaluación Florida A +, las escuelas de la Florida se clasifican en función del rendimiento de los estudiantes en el Examen de Evaluación Integral de la Florida. Anteriormente, cuando las escuelas recibían una calificación negativa en un lapso de cuatro años, a los estudiantes de esas escuelas se les ofrecían vales escolares (voucher) que los padres y tutores podrían utilizar para transferir a los estudiantes a una escuela pública tradicional u otra privada. En enero de 2006 la Corte Suprema de la Florida declaró que el voucher para las escuelas privadas del Programa de Responsabilidad Florida A + era inconstitucional, lo que elimina la amenaza de que esos estudiantes y los fondos fueran transferidos las escuelas privadas. Este choque exógeno nos permite comprobar si las amenazas de los vouchers y la financiación vinculada a estos estudiantes llevaron a aumentar el rendimiento estudiantil. No encontramos ninguna evidencia de que las amenazas de los vouchers generara mejorías académicas más allá de lo que se observó en las escuelas cuando se eliminó la amenaza de los vouchers.No âmbito do programa de avaliação Flórida A +, as escolas da Flórida são classificados com base no desempenho do estudante na Avaliação Global da Flórida. Anteriormente, quando as escolas receberam uma avaliação negativa em um período de quatro anos, aos alunos dessas escolas foram oferecidos vales escolares (voucher) que os pais e responsáveis poderiam utilizar para transferir os alunos para uma escola pública tradicional ou outra privada. Em janeiro de 2006, o Supremo Tribunal da Flórida decidiu que o programa de vales (voucher) para escolas particulares, do programa Flórida A + era inconstitucional, eliminando a ameaça de que esses alunos e os fundos fossem transferidos para escolas particulares. Este choque exógeno nos permite verificar se a ameaça dos vouchers e financiamentos vinculados a esses alunos levaram a aumentar o desempenho acadêmico dos alunos. Nós não encontramos nenhuma evidência de que a ameaça de vouchers gerara melhorias acadêmicas para além do que foi observado nas escolas onde a ameaça dos vouchers foi removida.

Thermodynamic formalism for the Lorentz gas with open boundaries in dd dimensions

A Lorentz gas may be defined as a system of fixed dispersing scatterers, with a single light particle moving among these and making specular collisions on encounters with the scatterers. For a dilute Lorentz gas with open boundaries in $d$ dimensions we relate the thermodynamic formalism to a random flight problem. Using this representation we analytically calculate the central quantity within this formalism, the topological pressure, as a function of system size and a temperature-like parameter \ba. The topological pressure is given as the sum of the topological pressure for the closed system and a diffusion term with a \ba-dependent diffusion coefficient. From the topological pressure we obtain the Kolmogorov-Sinai entropy on the repeller, the topological entropy, and the partial information dimension.Comment: 7 pages, 5 figure

Distribution of periodic points of polynomial diffeomorphisms of C^2

This paper deals with the dynamics of a simple family of holomorphic diffeomorphisms of \C^2: the polynomial automorphisms. This family of maps has been studied by a number of authors. We refer to [BLS] for a general introduction to this class of dynamical systems. An interesting object from the point of view of potential theory is the equilibrium measure $\mu$ of the set $K$ of points with bounded orbits. In [BLS] $\mu$ is also characterized dynamically as the unique measure of maximal entropy. Thus $\mu$ is also an equilibrium measure from the point of view of the thermodynamical formalism. In the present paper we give another dynamical interpretation of $\mu$ as the limit distribution of the periodic points of $f$

Squeezed light at sideband frequencies below 100 kHz from a single OPA

Quantum noise of the electromagnetic field is one of the limiting noise sources in interferometric gravitational wave detectors. Shifting the spectrum of squeezed vacuum states downwards into the acoustic band of gravitational wave detectors is therefore of challenging demand to quantum optics experiments. We demonstrate a system that produces nonclassical continuous variable states of light that are squeezed at sideband frequencies below 100 kHz. A single optical parametric amplifier (OPA) is used in an optical noise cancellation scheme providing squeezed vacuum states with coherent bright phase modulation sidebands at higher frequencies. The system has been stably locked for half an hour limited by thermal stability of our laboratory.Comment: 3 pages, 3 figure

Electrospray synthesis of PLGA TIPS microspheres

We successfully demonstrate the synthesis of polymer microspheres using a single electrospray source, and show their physical characterisation. Electrospray has proven to be a versatile method to manufacture particles, giving tight control over size with quasi-monodisperse size distributions. It is a liquid atomisation technique that generates a monodisperse population of highly charged liquid droplets over a broad size range (nanometres to tens of microns). The droplets contain liquid precursors for the in-flight synthesis of particles, and control over the trajectory of these droplets can be precisely manipulated with the use of electric fields to drive them to a grounded substrate. This study reports a method to synthesize poly(lactic-co-glycolic) acid (PLGA) microspheres using the electrospray and thermally induced phase separation (TIPS) techniques, followed by subsequent freeze-drying, for particle production. These microspheres are of interest as vehicles for controlled drug release systems