Modeling Amazon Deforestation for Policy Purposes

Brazil has long ago removed most of the perverse government incentives that stimulated massive deforestation in the Amazon in the 70s and 80s, but one highly controversial policy remains: Road building. While data is now abundantly available due to the constant satellite surveillance of the Amazon, the analytical methods typically used to analyze the impact of roads on natural vegetation cover are methodologically weak and not very helpful to guide public policy. This paper discusses the respective weaknesses of typical GIS analysis and typical municipality level regression analysis, and shows what would be needed to construct an ideal model of deforestation processes. It also presents an alternative approach that is much less demanding in terms of modeling and estimation and more useful for policy makers as well.Deforestation, Amazon, Brazil, econometric modeling

Preparing a High School Choral Program

Although many different methodologies exist within the realm of music education, the synthesis of those ideas is crucial when preparing for a profession in secondary music education. Teaching musical concepts through performance in choir is essential in developing well-rounded students as well as furthering students’ musical knowledge. By establishing a philosophy of music education, developing a syllabus, and outlining the process in preparing a choral program, other aspiring music educators will comprehend the work required of them in a more concrete manner as well as promote educators to demand more from their choral ensembles

Planning for peak oil: learning from Cuba's special period

It is against recent experiences of proliferative consumption of the earth’s resources that planners and politicians must confront the challenge of peak oil over the coming years. With so few examples of peak oil available worldwide, this paper explores the realities of this in Cuba after the collapse of the Soviet Union in 1989 – the so-called special period, which decimated the country’s imports of energy, food and other vital supplies. Drawing on primary research collected in Cuba during 2008 and in an attempt to stimulate debate about how western countries and cities might respond to future losses of global resources, this paper examines the policy responses implemented in Cuba in the fields of transport, spatial planning, agriculture and energy. Despite the Cuban situation being politically different from other countries and the fact that the loss of resources during the special period were abrupt and unplanned, it is argued that there is still considerable scope for a wider application of the concepts to other towns and cities, if not countries and cultures

Dating of Caves by Cosmogenic Nuclides: Method, Possibilities, and the Siebenhengste Example

Kozmični žarki povzročajo nastanek kozmogenih nuklidov na površini zemlje in tik pod njo. Za datiranje jamskih sedimentov sta posebej pomembna 10Be in 26Al, ki nastajata v kremenu. Ko je kamen na površini in izpostavljen kozmičnemu sevanju, nastajata v stalnem razmerju. Ko ga zanese v podzemlje, se tvorba kozmogenih nuklidov ustavi, nadaljuje pa se njihov radioaktivni razpad. Ker 26 Al razpada hitreje, lahko iz razmerja med njima izračunamo čas, ki je potekel odkar je kremen pod zemljo. Metodo lahko uporabimo na sedimentih, ki so pokopani oziroma v jami med 0.1 in 5 milijoni let. Na ta način lahko v idealnih primerih izračunamo hitrost vrezovanja dolin. Z opisano metodo smo določili starost najstarejših delov sistema Siebenhengste v Švici. Najstarejši sediment je star 4.4 ± 0.6 Ma in nakazuje, da je na tem območju potekalo zakrasevanje že v pliocenu.  Cosmic rays produce nuclides at and near the Earthʼs surface. 10Be and 26Al in quartz are of particular interest for dating cave sediments. These two nuclides are produced at the surface at a fixed ratio. If the quartz is carried from the surface into a cave, the sediment is shielded from additional cosmogenic nuclide production, and the inherited 10Be and 26Al decay radioactively. Because 26Al decays more rapidly than 10Be, the ratio of these two nuclides indicates the time since the sediment was washed underground. The burial dating method can be applied to sediments in the age range of approximately 0.1 to 5 Ma. In ideal cases, we get information about valley lowering rates. If the provenance of the sediment is known, averaged erosion rates of the source area can be estimated. The oldest cave phases of the Siebenhengste system, Switzerland, were dated using cosmogenic nuclides. The oldest sediment is 4.4 ± 0.6 Ma and thus indicates Pliocene karstification of the Siebenhengste.   

Feshbach Resonance Cooling of Trapped Atom Pairs

Spectroscopic studies of few-body systems at ultracold temperatures provide valuable information that often cannot be extracted in a hot environment. Considering a pair of atoms, we propose a cooling mechanism that makes use of a scattering Feshbach resonance. Application of a series of time-dependent magnetic field ramps results in the situation in which either zero, one, or two atoms remain trapped. If two atoms remain in the trap after the field ramps are completed, then they have been cooled. Application of the proposed cooling mechanism to optical traps or lattices is considered.Comment: 5 pages, 3 figures; v.2: major conceptual change

Tuning the interactions of spin-polarized fermions using quasi-one-dimensional confinement

The behavior of ultracold atomic gases depends crucially on the two-body scattering properties of these systems. We develop a multichannel scattering theory for atom-atom collisions in quasi-one-dimensional (quasi-1D) geometries such as atomic waveguides or highly elongated traps. We apply our general framework to the low energy scattering of two spin-polarized fermions and show that tightly-confined fermions have infinitely strong interactions at a particular value of the 3D, free-space p-wave scattering volume. Moreover, we describe a mapping of this strongly interacting system of two quasi-1D fermions to a weakly interacting system of two 1D bosons.Comment: Submitted to Phys. Rev. Let

Quasi-one-dimensional Bose gases with large scattering length

Bose gases confined in highly-elongated harmonic traps are investigated over a wide range of interaction strengths using quantum Monte Carlo techniques. We find that the properties of a Bose gas under tight transverse confinement are well reproduced by a 1d model Hamiltonian with contact interactions. We point out the existence of a unitary regime, where the properties of the quasi-1d Bose gas become independent of the actual value of the 3d scattering length. In this unitary regime, the energy of the system is well described by a hard rod equation of state. We investigate the stability of quasi-1d Bose gases with positive and negative 3d scattering length.Comment: 5 pages, 3 figure

Synemin and vimentin are components of intermediate filaments in avian erythrocytes

Synemin, a high-molecular-weight protein associated with intermediate filaments in muscle, and vimentin, an intermediate-filament subunit found in many different cell types, have been identified by immunologic and electrophoretic criteria as components of intermediate filaments in mature avian erythrocytes. Desmin, the predominant subunit of intermediate filaments in muscle, has not been detected in these cells. Two dimensional immunoautoradiography of proteolytic fragments of synemin and vimentin demonstates that the erythrocyte proteins are highly homologous, if not identical, to their muscle counterparts. Double immunoflurorescence reaveals that erythrocyte synemin and vimentin co-localize in a cytoplasmic network of sinuous filaments that extends from the nucleus to the plasma membrane and resists aggregation by colcemid. Erythrocytes that are attached to glass cover slips can be sonicated to remove nuclei and nonadherent regions of the plasma membrane; this leaves elliptical patches of adherent membrane that retain mats of vimentin- and synemin-containing intermediate filaments, as seen by immunofluorescence and rotary shadowing. Similarly, mechanical enucleation of erythrocyte ghosts in suspension allows isolation of plasma membranes that retain a significant fraction of the synemin and vimentin, as assayed by electrophoresis, and intermediate filaments, as seen in thin sections. Both synemin and vimentin remain insoluble along with spectrin and actin, in solutions containing nonionic detergent and high salt. However, brief exposure of isolated membrane to distilled water releases the synemin and vimentin together in nearly pure form, before the release of significant amounts of spectrin and actin. These data suggest that avian erythrocyte intermeditate filaments are somehow anchored to the plasma membrane; erythrocytes may thus provide a simple system for the study of intermediate filaments and their mode of interaction with membranes. In addition, these data, in conjunction with previous data from muscle, indicate that synemin is capable of associating with either desmin or vimentin and may thus perform a special role in the structure or function of intermediate filaments in erythrocytes as well as muscle

Nonclassical paths in the recurrence spectrum of diamagnetic atoms

Using time-independent scattering matrices, we study how the effects of nonclassical paths on the recurrence spectra of diamagnetic atoms can be extracted from purely quantal calculations. This study reveals an intimate relationship between two types of nonclassical paths: exotic ghost orbits and diffractive orbits. This relationship proves to be a previously unrecognized reason for the success of semiclassical theories, like closed-orbit theory, and permits a comprehensive reformulation of the semiclassical theory that elucidates its convergence properties.Comment: 5 pages, 4 figure

Quantum Monte Carlo study of quasi-one-dimensional Bose gases

We study the behavior of quasi-one-dimensional (quasi-1d) Bose gases by Monte Carlo techniques, i.e., by the variational Monte Carlo, the diffusion Monte Carlo, and the fixed-node diffusion Monte Carlo technique. Our calculations confirm and extend our results of an earlier study [Astrakharchik et al., cond-mat/0308585]. We find that a quasi-1d Bose gas i) is well described by a 1d model Hamiltonian with contact interactions and renormalized coupling constant; ii) reaches the Tonks-Girardeau regime for a critical value of the 3d scattering length a_3d; iii) enters a unitary regime for |a_3d| -> infinity, where the properties of the gas are independent of a_3d and are similar to those of a 1d gas of hard-rods; and iv) becomes unstable against cluster formation for a critical value of the 1d gas parameter. The accuracy and implications of our results are discussed in detail.Comment: 15 pages, 9 figure